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Mississippian sedimentology, depositional and diagenetic control on the Kisbey sandstone petroleum reservoir… Howard, Patrick 2000

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MISSISSIPPIAN SEDIMENTOLOGY, DEPOSITIONAL AND DIAGENETIC CONTROL ON THE KISBEY SANDSTONE PETROLEUM RESERVOIR DEVELOPMENT, WILLISTON BASIN By Patrick Howard B.Sc , California State University, Bakersfield, 1997 A THESIS SUBMITED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF M A S T E R OF SCIENCE in THE F A C U L T Y OF G R A D U A T E STUDIES Department of Earth and Ocean Sciences We accept the thesis as conforming to the required standard THE UNIVERSITY OF BRITISH C O L U M B I A April 2000 © Patrick Howard, 2000 In presenting t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that permission f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the head of my department or by h i s or her r e p r e s e n t a t i v e s . I t i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission. Department of The U n i v e r s i t y of B r i t i s h Columbia Vancouver, Canada Date j4pr> / ^ > ^ ^cD&C\ A B S T R A C T The Mississippian, Kisbey Sandstone, of the Williston Basin comprises the siliciclastic component of the mixed carbonate-siliciclastic-evaporitic ramp deposits of the Frobisher-Alida beds. The Kisbey Sandstone comprises multiple laterally and stratigraphically discontinuous intervals of quartz arenite which are regionally uncorrectable. Sandstone thickness ranges from <1 to 20 metres with the thicker intervals (3-20 metres) trending NE-SW, perpendicular to the inferred shoreline of Frobisher-Alida beds. A full geophysical log suite consisting of the gamma ray, photoelectric, density and neutron logs are necessary for identification and mapping of the sandstone. The sandstone is predominately massive with rare planar cross bedding and parallel laminations. The massive texture of the sandstone makes depositional interpretations ambiguous. The carbonate lithofacies associated with the Kisbey Sandstone provide a depositional framework for interpretation of the Kisbey Sandstone depositional environments. The primary carbonate lithofacies and depositional environments are open marine crinoidal grainstone and mudstone, pisolitic-ooilitic shoals, protected peloidal grainstone and mudstone Three depositional environments of the sandstone are recognized: 1) wave influenced sandstone shoals; 2) storm-transported sandstone to the open marine environment; and 3) tidal channel sandstone. The interpreted depositional environments reflect autocyclic influences acting on the Frobisher-Alida ramp. Allocyclic influences, such as a relative drop in sea level, do not directly influence the deposition of the Kisbey Sandstone, but did lead to progradation of the restricted marine and evaporitic ii environments on the Frobisher-Alida ramp. An allocyclic influence is however necessary to transport the Kisbey Sandstone tb the Frobisher-Alida ramp. Eolian transport, analogous with the modern southeast coast of Qatar, is a possible mechanism that controls the initial influx of the Kisbey Sandstone onto the Frobisher-Alida ramp. The Kisbey Sandstone average porosity is 17% and average permeability is 140 md; however, the porosity and permeability values vary greatly in a seemingly unpredictable fashion. The apparent non-uniform distribution of porosity and permeability is characteristic of most sandstone intervals in the study area. Core descriptions, petrographic and scanning electron microscope examination of the Kisbey Sandstone indicates sandstone cements consist only of dolomite and anhydrite. Dolomite is pervasive in the Kisbey Sandstone, but due to abundant intercrystalline porosity the sandstone remains porous and permeable. Anhydrite occurs as patchy zones 2 cm in diameter and along individual lamina, completely occluding pores, has a random distribution at the core sample scale, and correlates with zones of low permeability and porosity. Both dolomite and anhydrite are interpreted to have cemented the Kisbey Sandstone during the early marine stage of diagenesis. Dissolution occurred during sub-aerial exposure and development of the sub-Mesozoic Unconformity and is responsible for partial dissolution and random distribution of the anhydrite cement. Although the Kisbey Sandstone intervals have an arbitrary distribution of low porosity and permeability zones, most sandstone intervals in the study area have good reservoir potential. in TABLE OF CONTENTS Abstract ii Table of Contents iv List of Figures vii List of Tables ix Acknowledgements x CHAPTER ONE: INTRODUCTION 1 1.1 Introduction 1 1.2 Depositional Controls of the Kisbey Sandstone 1 1.3 Diagenetic Development of the Kisbey Sandstone 2 1.4 Structure of Thesis 3 1.5 References Cited 4 CHAPTER TWO: SEDIMENTOLOGY AND DEPOSITIONAL CONTROLS OF THE KISBEY SANDSTONE, MISSISSIPPIAN, WILLISTON BASIN 5 2.1 Abstract 5 2.2 Introduction 6 2.3 Tectonic and Stratigraphic Framework 7 2.3.1 Tectonic framework 7 2.3.2 Stratigraphic framework 9 2.4 Methods 12 2.5 Log Analysis 14 2.6 Sedimentology and Interpretations 16 IV 2.6.1 Kisbey Sandstone sedimentology 16 2.6.2 The Frobisher-Alida beds-carbonate and evaporite sedimentology .... 25 2.6.3 Depositional environments of the Frobisher-Alida ramp 33 2.6.4 Depositional environments of the Kisbey Sandstone 35 2.7 Discussion 48 2.7.1 Sea level control, incised valley fill and siliciclastic influx 48 2.7.2 Depositional model of the mixed carbonate-siliciclastic Frobisher-Alida beds 55 2.8 Conclusions 55 2.9 References Cited 58 CHAPTER THREE: DIAGENETIC DEVELOPMENT OF THE KISBEY SANDSTONE RESERVOIRS, MISSISSIPPIAN, WILLISTON BASIN 62 3.1 Abstract 62 3.2 Introduction 63 3.3 Geologic Setting 64 3.3.1 Stratigraphy 64 3.3.2 Frobisher-Alida sedimentology 64 3.4 Methods 67 3.5 Results: Reservoir Properties and Diagenetic Characteristics 67 3.5.1 Kisbey Sandstone diagenetic characteristics 67 3.5.2 Kisbey Sandstone reservoir properties 70 3.6 Discussion 73 3.6.1 Origin and Timing of the Kisbey Sandstone diagenetic events 73 V 3.6.2 Paragenetic development of the Kisbey Sandstone reservoirs 76 3.6.3 Predictability of reservoir properties of the Kisbey Sandstone 78 3.6.4 Conclusions 80 3.7 References Cited 81 CHAPTER FOUR: CONCLUSIONS 84 4.1 Sedimentology and Depositional Model for the Kisbey Sandstone 84 4 2 Diagenesis of the Kisbey Sandstone 84 4.3 Future Research Directives 85 4.4 References Cited 87 APPENDIX 1: GEOPHYSICAL LOG ANALYSIS 88 APPENDIX 2: THIN SECTION DESCRIPTIONS 102 APPENDIX 3: TRACE ELEMENT ANALYSIS OF THE ANHYDRITE 127 APPENDIX 4: CORE DESCRIPTIONS 129 vi LIST OF FIGURES Figure 2.1. Location of the Williston Basin 8 Figure 2.2. Paleo-tectonic element map of the early Carboniferous 10 Figure 2.3. Stratigraphic column of the Mississippian in the Williston Basin .... 11 Figure 2.4 Location of the study area 13 Figure 2.5. Geophysical log correlation with core well 4-12-4-33W1 15 Figure 2.6. Geophysical log correlation with core well 1-32-7-4W2 17 Figure 2.7. Map of the NE-SW Kisbey Sandstone trends 19 Figure 2.8. Contact abundance and type versus sandstone thickness 21 Figure 2.9. Core photos of sandstone contacts 22 Figure 2.10. The Kisbey Sandstone 24 Figure 2.11. Crinoid lithofacies, open marine environment 28 Figure 2.12. Lithofacies of the Restricted marine environment 30 Figure 2.13. Anhydrite lithofacies, evaporitic environment 34 Figure 2.14. Diagrammatic map and cross section views of the Frobisher-Alida depositional environments 36 Figure 2.15. Composite stratigraphic column of the Frobisher-Alida beds at the Kisbey Pool 38 Figure 2.16. Sandstone isopach map of the Kisbey Pool 39 Figure 2.17. Stratigraphic cross section through the Kisbey Pool 40 Figure 2.18. Sandstone isopach map of the southwest portion of the Areola Pool ... 42 Figure 2.19. Structural fence diagram of the southwest portion of the Areola Pool 43 Figure 2.20. Composite stratigraphic columns of the Frobisher-Alida beds on the southeastern part of the study area 45 Figure 2.21. Structuaral fence diagram of the southeastern part of the study area 47 Figure 2.22. Stacked clastic-dolomudstone sequences 49 Figure 2.23. Composite stratigraphic columns of the Frdbisher-Alida beds from the Kisbey Pool and the southeastern part of the study area 52 Figure 2.24. Diagrammatic map and cross section views of the Frobisher-Alida depositional environments and the controls on Kisbey Sandstone deposition 56 Figure 3.1. Stratigraphic column of the Mississippian in southeastern Saskatchewan 65 Figure 3.2. Study area and sandstone trend map 68 Figure 3.3. Characteristic of the dolomite cement 69 Figure 3.4. Characteristic of the anhydrite cement 71 Figure 3.5. The permeability and porosity of select Kisbey Sandstone Intervals 72 Figure 3.6. Permeability and porosity of various Kisbey Sandstone Pools and Kisbey Sandstone trends 74 Figure 3.7. Diagrammatic representation of the three recognized diagenetic events: Dolomitization, anhydrite cementation, and dissolution 77 Figure 3.8. Lithology and diagenetic log and reported permeability and porosity of well 4-12-4-33Wl 79 LIST O F T A B L E S Table 2.1. Lithofacies transition matrix 20 Table 2.2. Recognized carbonate and evaporite lithofacies descriptions .... 26 ix A K N O W L E D G E M E N T S Many organizations and individuals help make this project a success, their hard work and help is appreciated. Numac Energy provided financial support and logistical support for the project. The Saskatchewan Energy and Mines Subsurface Geological Laboratory provided access to the core. Dr. Don Kent was gracious with his time and was available for many questions while I was at the core lab in Regina. Marc Bustin supervised the research project. His numerous reviews of my thesis has made me a better writer. Kurt Grimm and Paul Smith were gracious with their time and review of the thesis. A big thank you also goes to my family, especially my wife Dana, for all of their support through these years while I attended U B C . C H A P T E R O N E : I N T R O D U C T I O N 1.1 Introduction The Kisbey Sandstone is a petroleum producing lithofacies of Mississippian strata in the Williston Basin. Despite its significance as a known petroleum reservoir, the Kisbey Sandstone has remained a poorly understood unit because: 1) limited production from the Kisbey Sandstone as compared to Mississippian carbonate reservoirs in the Williston Basin has not provided economic incentive to understand the sandstone sedimentology; 2) there are few modern analogs of mixed carbonate-siliciclastic deposits to make comparisons with the Kisbey Sandstone and associated carbonate lithofacies; and 3) the inability to regionally correlate the Kisbey Sandstone with geophysical logs makes subsurface investigation difficult. In order to develop the Kisbey Sandstone as a future petroleum reservoir, knowledge of the sandstone depositional environments and diagenesis needs to be acquired. These two aspects of reservoir development (depositional control, and diagenetic control) are investigated in this thesis. Chapter two presents interpretations of the Kisbey Sandstone depositional environments. Chapter three investigates the diagenetic development of the Kisbey Sandstone. 1.2 Depositional controls on the Kisbey Sandstone To date, there are no published papers that focus on the Kisbey Sandstone sedimentology and interpretations of depositional environments. Previous research that has focused on aspects of the Mississippian carbonate sedimentology within the Williston Basin present limited documentation and interpretation of the Kisbey Sandstone. Edie 1 (1958) and Fuzesy (1960) published cross sections correlating both two and one Kisbey Sandstone intervals respectively, with out an explanation of the sandstone depositional environments. These correlations, based mostly on gamma ray markers alone, do not necessarily correlate quartz arenite lithology but also correlate a stratigraphically equivalent argillaceous dolomite. Only two interpretations of Kisbey Sandstone depositional environments are found in the literature. The Kisbey Sandstone is interpreted as both incised valley fill, in North Dakota (Witter, 1988), and as sandstone shoals, at Lost Horse Hi l l Field, in Saskatchewan (Perras, 1990). These previous interpretations, however, lack regional perspective and detailed documentation of the Kisbey Sandstone. The scope of chapter 2 is to provide regional documentation of the Kisbey Sandstone sedimentology, the sedimentology of the associated carbonate lithofacies, and to interpret the depositional environments of the Kisbey Sandstone. 1.3 Diagenetic Development of the Kisbey Sandstone The occurrence of the Kisbey Sandstone within a carbonate stratigraphy suggest typical carbonate diagenetic events, such as dolomitization and dissolution, could significantly effect the porosity and permeability development of the Kisbey Sandstone. Previous studies on the diagenesis of the Kisbey Sandstone are limited to the documentation of pore filling dolomite, anhydrite cement, and mercury porosimetry analysis of the Kisbey Sandstone located at Lost Horse Hi l l Field (Perras, 1990). The focus of chapter 3 is to document the regional diagenesis of the Kisbey Sandstone and interpret the paragenetic events, which created Kisbey Sandstone with good reservoir potential. 2 1.4 Structure of Thesis This thesis is presented as two individual papers, chapter two and three, which may be read without reference to the preceding chapters. Chapter 2 documents and interprets the sedimentology of the Kisbey Sandstone. The specific objectives of this chapter are: 1) describe the Kisbey Sandstone sedimentology on a regional scale (i.e. larger study area than a single field); 2) interpret the sandstone depositional environments with the incorporation of the associated carbonate lithofacies used as environmental indicators of sandstone depositional environments; and 3) provided an assessment of autocyclic versus allocyclic controls on the Kisbey Sandstone deposition. Chapter three investigates the Kisbey Sandstone diagenesis. The specific objectives of this chapter are: 1) document the porosity, permeability, cement type arid distribution for Kisbey Sandstone intervals throughout the study area; and 2) interpret the timing and origin of diagenetic events that have created Kisbey Sandstone intervals with good reservoir potential. 3 1.5 References Cited Perras, G. 1990. Sedimentological and Reservoir Characteristics of the Frobisher-Alida Beds Lost Horse Hi l l Field, Southeastern Saskatchewan. Unpublished Msc. Thesis. The University of Regina. 18lp. Witter, D. N . 1988. Stratal Architecture and Volumetric Distribution of Facies Tracts, Upper Mission Canyon Formation (Mississippian) Williston Basin, North Dakota. Unpublished Msc. Thesis, Colorado School of Mines. 142p. 4 CHAPTER TWO: SEDIMENTOLOGY AND DEPOSITIONAL CONTROLS OF THE KISBEY SANDSTONE, MISSISSIPPIAN, WILLISTON BASIN. 2.1 Abstract The Mississippian, Frobisher-Alida beds of the Williston Basin comprise a mixed carbonate-siliciclastic-evaporitic unit. The Kisbey Sandstone constitutes the siliciclastic component of the Frobisher-Alida ramp and is a locally important, although enigmatic, petroleum reservoir. From core descriptions, lithofacies interpretations and geophysical log correlation the Kisbey Sandstone is defined as multiple laterally and stratigraphically discontinuous intervals of quartz arenite that are regionally uncorrelative. Sandstone thickness ranges from <1 to 20 metres with the thicker intervals (3-20 metres) trending NE-SW. A full geophysical log suite is necessary for identification and mapping of the sandstone. The sandstone is predominantly massive with rare planar cross bedding and parallel laminations. The massive texture of the sandstone makes depositional interpretations ambiguous. The associated carbonate lithofacies provide a depositional framework for interpretation of the Kisbey Sandstone, of which the major carbonate lithofacies are a regressive sequence of crinoidal open marine lithofacies, pisolitic-oolitic shoals, protected peloidal grainstone and mudstone, capped by the Frobisher Evaporite. Three depositional environments/mechanisms of the sandstone are recognized: 1) wave-influenced sandstone shoals; 2) storm-transported sandstone to the open marine environment; and 3) tidal channel sandstone. The interpreted depositional environments reflect autocyclic influences acting on the Frobisher-Alida ramp. Allocyclic influences, such as a relative drop in sea level, did not obviously influence the deposition of the 5 Kisbey Sandstone, but did lead to a regressive of the restricted marine and evaporitic environments on the Frobisher-Alida ramp. 2.2 Introduction The Mississippian Kisbey Sandstone in the Williston Basin is a locally important, although enigmatic, petroleum reservoir within the mixed carbonate-siliciclastic-evaporitic Frobisher-Alida beds. The Kisbey Sandstone, in the subsurface of southeastern Saskatchewan, has been an oil producing lithofacies since the early 1980's. Recent discoveries (in 1996) in southeastern Saskatchewan (T4R33W1) has lead to renewed interest in exploration for reservoir quality Kisbey Sandstone. In regional cross sections of Mississippian stratigraphy in the subsurface of southeastern Saskatchewan, Edie (1958) indicates the occurrences of two Kisbey Sandstone intervals, while Fuzesy (1960) correlated one Kisbey Sandstone interval. Edie (1958) and Fuzesy (1960) described these Kisbey Sandstone intervals as undifferentiated quartz arenite and argillaceous dolomite. Witter (1988) interpreted the Kisbey Sandstone as incised channel fill sands correlative with the K - l marker in the subsurface of North Dakota. Perras (1990), in a local subsurface field study of the Frobisher-Alida beds at Lost Horse Hi l l Field, southeastern Saskatchewan, interpreted a cross-bedded Kisbey Sandstone lithofacies as stacked migrating dunes/mega-ripples reworked into accretion beaches or spits along carbonate oolitic-pisolitic shoals. A massive Kisbey Sandstone lithofacies was interpreted as a nearshore marine shelf sandstone (Perras, 1990). These previous interpretations lack regional perspective (e.g. Perras, 1990) or lack detailed documentation of the Kisbey Sandstone sedimentology (e.g. Edie, 1958; Fuzesy, 1960; Witter, 1988). 6 Further documentation of the sandstone sedimentology and interpretation of depositional environments will assist exploration efforts for more oil producing Kisbey Sandstone reservoirs. The purpose of this paper is to document the stratigraphic framework and interpret the depositional environments of the Kisbey Sandstone. Core descriptions and cross sections indicate the Kisbey Sandstone is a massive fine-grained quartz arenite that comprises multiple laterally and stratigraphically discontinuous NE-SW trending intervals that are only locally correlatable. The massive texture makes depositional interpretation of the Kisbey Sandstone difficult. The associated carbonate lithofacies however, provide environmental indicators that permit depositional interpretations of the Kisbey Sandstone. In this study, a depositional model is proposed to include for both autocyclic and allocyclic influences on the Kisbey Sandstone deposition. 2.3 Tectonic and Stratigraphic Framework 2.3.1 Tectonic framework: The Kisbey Sandstone is located in the Williston Basin, an intracratonic basin in north central North America (Fig. 2.1). The Williston Basin covers an area of approximately 345,000 km and contains a succession of Cambrian to Tertiary siliciclastic and carbonate strata up to 5,000 metres thick. The arid climate of the Williston Basin during the Early Carboniferous was in part controlled by the paleo-latitude of the basin, which was located approximately at 5° north latitude (Gutshick and Sandberg, 1983). The paleo-geography of the Williston Basin, during the early Carboniferous was influenced by the tectonic evolution of the western North American continental margin and basement tectonics within the basin. The major tectonic elements 7 Figure 2.1: Location of the Williston Basin. during the Carboniferous were the Antler Oogenetic Belt, Antler foreland basin, the Prophet Trough and Central Montana Trough (Richards, 1989; Fig. 2.2). The Williston Basin was confined by topographic highs of the Transcontinental Arch to the southeast, the Severn Arch to the northeast and the emerging Sweetgrass Arch to the northwest (Fig. 2.2). The Central Montana Trough (seaway) connected the Williston Basin to the west with the Antler Foreland Basin. During the early Carboniferous, an epeiric sea extended from what is the present-day southwestern United States north to the Williston Basin, the Peace River Embayment, and Yukon Territory. 2.3.2 Stratigraphic framework: There are many nomenclature schemes used for Mississippian subsurface stratigraphy in the Williston Basin; a comprehensive review is given by Carlson and Lefever (1987). Mississippian strata in the Williston Basin are mainly composed of carbonate sediments of the Madison Group which includes the Kisbey Sandstone. In the subsurface of southeastern Saskatchewan the Madison Group is divided into informal units termed beds, based on geophysical log markers (Fig. 2.3; Saskatchewan Geological Survey, 1958; Kent, 1987; Gerhard et al., 1991). This paper uses the nomenclature established by the Saskatchewan Geological Survey (1958). Mississippian strata are unconformably overlain by the Triassic Watfous Formation. Mississippian beds sub-crop at the sub-Mesozoic unconformity producing NW-SE sub-crop trends, along which many of the Mississippian hydrocarbon pools occur. The upward succession of informal beds comprise an overall regressive mega-sequence (Kent, 1987) punctuated with smaller scale regressive and transgressive strata (Harris et al. 1966). 9 Kibbey Formation 8 O O CA 1 r1 r» L Charles E Formation • r-1 r"! ^1 i / 1 / ' j _ Mission Canyon _ | L Formation L I I E Lodgepole ^ Formation C _i_ Bakken Formation-Informal beds in southeastern Saskatchewan Midale beds Frobisher Evaporite S ^ Hastings Evaporite U \y U ^ K i s b e y ^ F Sandstone; sandstone and black shale basinal to peritidal limestone and dolomite terrestrial sandstone, siltstone and mudstone Figure 2.3: Stratigraphic column of the Mississippian in southeastern Saskatchewan (left column). Center column is the informal subsurface intervals of the Madison Group (Saskatchewan Geological Survey, 1958) and the column on the right shows other recognized informal units including the Kisbey Sandstone within the Frobisher-Alida beds (Fuezey, 1960). 11 There is no sequence stratigraphic framework published for the Mississippian in the Williston Basin. However, Reid and Dorobek (1993) propose a sequence stratigraphic framework for Madison Group equivalent strata along the platform margin located in present-day Idaho and Montana. Reid and Dorobek (1993) correlated some of their recognized sequence stratigraphic surfaces of the platform margin strata with subsurface strata in North Dakota by correlating composite biozones established by Sando (1985). Two of the maximum flooding surfaces of Reid and Dorobek (1993) were correlated with the base and the top of the Frobisher-Alida beds and their type 2 sequence boundary (their SB2[B]) correlates with the K - l marker of Harris et al. (1966). 2.4 Methods In order to determine the log suite necessary for identification of the Kisbey Sandstone, correlation of core with geophysical logs was preformed with seven representative wells. One hundred twenty-five cores were described from the study area (Fig. 2.4) in which 9 carbonate, evaporite, and siliciclastic lithofacies were recognized. Sixty-two thin sections were also examined in order to confirm hand specimen identification of lithofacies. The use of cores for correlations and mapping of the Kisbey Sandstone was supplemented with 132 wells with geophysical log suites comprised of the gamma ray, photoelectric, neutron and density logs. Nineteen cross sections were constructed in order to describe vertical and lateral lithofacies relationships from which depositional environments were interpreted. 12 DO C "o, u c o i l O 13 2.5 Log Analysis Geophysical log identification of the Kisbey Sandstone proved difficult to impossible depending on the geophysical logs available. The geophysical log signature of the Kisbey Sandstone responds not only to the quartz arenite lithology but also to the pore filling mineral phases, dolomite and anhydrite. Dolomite is the predominant pore filling mineral phase and has intercrystalline porosity. Anhydrite has a non-uniform patchy distribution and occludes porosity. Below is a description of the criteria used for sandstone identification with examples from two cored wells (4-12-4-33W1 and 1-32-7-4W2). Well 4-12-4-33Wl (Fig. 2.5) has a full log suite: gamma ray, sonic, photoelectric (Pe), density, and neutron logs. Two Kisbey Sandstone intervals occur in core. The upper, 20 metre thick, sandstone is identified with the density/neutron logs by cross over of the two curves when calculated with a limestone matrix value. Typical photoelectric index values for the Kisbey Sandstone range between 2 to 3 with the higher values occurring at bed contacts. The photoelectric index value for quartz is 1.8 (Schlumberger, 1989); therefore the photoelectric index values that correlate with sandstone intervals are also affected by cement types, (dolomite and anhydrite) and bed boundaries. There is an increase in the gamma ray count (15-22 API) correlative with the sandstone intervals, but high gamma ray spikes are also associated with the dolomudstone lithofacies, which commonly occur under, over, and interbedded with the Kisbey Sandstone. Gamma ray spikes are also correlative with stylolite zones (appendix 1 well 9-6-7-4W2). The sonic log (which is the poorest indicator of sandstone) correlative with the upper sandstone has 14 15 a faster interval transit times relative to the over and underlying carbonates. The sonic log correlative with the lower sandstone interval is indistinct from the sonic signature of the adjacent carbonates. The minimum thickness of sandstone that can be identified with a full log suite (gamma ray, sonic, Pe, density, and neutron) is about one metre. Well 1-32-7-4W2 (Fig. 2.6) demonstrates the difficulty of sandstone identification with a minimum log suite (gamma ray and sonic). The thickness of the sandstone in core is five metres. The gamma ray response ranges from 16-56 API units. The correlative sonic response is variable and indistinguishable from the variable sonic response of the adjacent carbonates. Due to the difficulty in unequivocally recognizing sandstone with geophysical logs, only cored wells and wells with a gamma ray, Pe, density and neutron logs were utilized in this study for mapping and correlation. The carbonate lithofacies were also correlated with the geophysical logs. The only carbonate lithofacies identifiable with a full geophysical log suite was a dolomudstone. The dolomudstone lithofacies was identified by a separation of the density and neutron curves (when calculated with a limestone matrix) and Pe index values ranging from 3-4 (e.g. Well 4-12-4-33W1; Fig. 2.5). 2.6 Sedimentology and Interpretations 2.6.1 Kisbey Sandstone sedimentology: The Kisbey Sandstone in this paper is used to refer to multiple discontinuous quartz arenite intervals within the Frobisher-Alida beds. Regional correlation of the Kisbey Sandstone intervals across the study area has proved difficult due to poor log control, the discontinuous nature of the sandstone and erosion of some of the intervals by the sub-Mesozoic unconformity. Consequently the Kisbey Sandstone stratigraphy can 16 e core I •:;.;J\ V " 1 , Hi 1 1 u 1 1 "S i f § en 1 i 1.1 Is I i .S ^  s -§ s 5 9* iUfi1 s i •s-g g c CN C N CO £ o o > a o 1 o o o 13 _o ft O <u o C N <u 17 not be correlated across the study area. The Kisbey Sandstone intervals range in thickness from <1 up to 20 metres. Throughout the study area, the thinner sandstone intervals (<3 metres) predominate. From the examined 125 core wells and additional 132 wells with a geophysical log suite necessary for Kisbey Sandstone identification, thick sandstone intervals (3-20 m) are identified in wells which align in a NE-SW orientation comprising five 'trends' within the study area (Fig 2.7). Three of the five trends contain two Kisbey Sandstone intervals. The thick Kisbey Sandstone intervals are truncated at the sub-Mesozoic unconformity to the northeast. The extent of the thick Kisbey sandstone interval to the southeast is unknown due to poor well control. Only five to ten wells define a single Kisbey Sandstone trend which made construction of isopach maps difficult. The Kisbey Sandstone intervals are in contact with all the carbonate and evaporite lithofacies, but predominantly with the tidal flat dolomudstone lithofacies (Table 2.1). Contacts of the Kisbey Sandstone intervals with over and underlying lithofacies are both gradational and sharp. There is no correlation of contact type (gradational or sharp) with the sandstone thickness (Fig. 2.8), location of the sandstone intervals within the study area, with adjacent lithofacies or with the upper versus lower contact of a sandstone interval. Overall it is difficult to determine with certainty if gradational or sharp contacts predominate due to the large number of sandstone contacts either obscured by anhydrite nodules, eroded, not cored, or destroyed during coring (Fig. 2.8). The typical gradational contact grades over 5-10 cm (Fig. 2.9a). Sharp contacts are planar (Fig. 2.9b). There are rare occurrences of load and flame structures at the basal contact of some sandstone intervals. 18 -a u c tU X u 05 CO _o .2 'to J3 & . o -o e>0 § -o B Sw o u c o -a u to CO u c 0 -a c/3 u o T3 C 6 CO 3 o -g o T3 C CO fli II 1 U c S cu S t% a Q CM O . „ Total O CN CO o> r~ CO CD CN CO CO cn CO * -lO CM S m OJ x— CO c o q-to ^ TJ C 3 CO CO *— O CM Hfliililii? CO CO O T - o 5> Open Marine TJ O C B O o o O o CM o o CO OJ Restricted Marine •B CO 8 g I °> O o o o KO o o o CO CN x— Restricted Marine CO II TJ ° 1 CN CO CM 00 r- CN o o CN CO CN Restricted Marine OJ c s eo TJ 3 E o "5 TJ C L CO O l co o x- 00 CO $ O CO Restricted Marine S 2 a s t i l O l CD CO o OJ o o oo CM Restricted Marine ra ® I'1 Q OJ !•- OO o CO o CN OJ o o w s Restricted Marine o S = 2 81 O o o o CN CN o o CM o Restricted Marine i = m o o m CN OJ CO CO O CN o o 00 t— OJ o Evaporitic U) TJ CO >. < w O to o o oo o o 00 CO CN 0) 'S L L -If it 5-CO c a 1 2 » 8 81 Ol P P Q oi cu 5 i s L U OJ CO c 3 in E o o TJ CD « C E 2 — in TJ O g B CO in c « 2 3 2 3 "co I 0 1 TJ '8 CO c « TJ c a 1 |2 •c > w O S • T . S c S saiOBjoinii SuiApapun 20 Figure 2.9: A) Core photo of thin (12 cm) sandstone showing a typical gradational contact of the Kisbey Sandstone with the dolomudstone lithofacies; from well 8-30-7-5 W2,1248 m. B) Core well 4-12-4-33W1 showing sharp contacts of a Kisbey Sandstone interval at 1192 m. A l l scale bars are 3 cm. 22 The Kisbey Sandstone is predominantly massive (Fig. 2.10). Typical sedimentary structures are parallel lamination, planar cross bedding and rare ripple lamination (Fig. 2.10). The predominant dip angle of lamina and foresets is 20°, but range from horizontal to a maximum of 30°. Sedimentary structures are faint and randomly distributed. It is impossible to determine if the massive texture is due to bioturbation, lack of structure development during deposition, or i f primary sedimentary structures are obscured by cementation or oil staining. Compositionally the Kisbey Sandstone is a fine-grained, sub-angular to sub-rounded quartz arenite (Fig. 2.10) with minor amounts of feldspar and chert (<3 %). There is rare oolitic grainstone in which quartz grains comprise the nuclei of the ooids (Fig. 2.10). Pore filling minerals consists of dolomite and anhydrite. Zones of dolomite that are larger than the quartz grains are probably limestone grains that have been dolomitized. Porosity averages 17% and ranges in a single core, from 7% to 32%. Permeability averages 140 md with a range of 3000 md to <1 md. The porosity and permeability are primarily controlled by the varying amount of dolomite and anhydrite. Interpretation: Because of the predominance of massive sandstone, interpretation based solely on sandstone sedimentology is difficult. Interpretations of the Kisbey Sandstone depositional environments can however, be further developed by using the environmental indicators provided by the associated carbonate lithofacies. Therefore the carbonate and evaporite lithofacies of the Frobisher-Alida beds will be briefly described and interpreted in the following section followed by descriptions and interpretations of the Kisbey Sandstone at three localities within the study area in which the sandstone has different carbonate lithofacies associations. 23 3 cm Figure 2.10: The Kisbey Sandstone. A) Core photograph of a massive sandstone; from well 8-6-3-32W1, 3966 ft. B) Core photograph of a parallel laminated sandstone; patchy appearance is due to variation in abundance of anhydrite cement; from well 4-12-4-33W1,1192.5 m. C) Core photograph of a horizontally laminated sandstone; from well 11-1-6-3W2,1139.8 m. D) Core photograph of a planar cross bedded sandstone; from well 16-35-3-33W1,1194.2 m. E) Photomicrograph of the Kisbey Sandstone; Q=quartz; D=dolomite; from well 5-12-8-4 W2, 1187.4 m. F) Photomicrograph of the Kisbey Sandstone; quartz grains are coated with calcite forming an oolitic grainstone; from well 13-13-8-6W2; 1198.8 m. 24 2.6.2 The Frobisher-Alida beds-carbonate and evaporite sedimentology: The Frobisher-Alida beds occur throughout southeastern Saskatchewan but become undifferentiated from other Mississippian beds west of 104° longitude (west of range 15 west of the 2 n d meridian; Fuzesy, 1960). The Frobisher-Alida beds have an average complete thickness of 115 metres and thin to 0 metres at the subcrop edge (Fuzesy, 1960). The paleo-shoreline during deposition of early Mississippian carbonates, such as the Frobisher-Alida beds, is interpreted to have been oriented NW-SE in Southeastern Saskatchewan as indicated by the shallowing upwards cycles of Mississippian strata that trend NW-SE across southeastern Saskatchewan (Kent, 1987). The carbonate sedimentology of the Frobisher-Alida beds has been extensively studied, and is described as a regressive sequence of which the major lithofacies are: crinoidal open marine lithofacies, pisolitic-oolitic shoals, protected peloidal grainstone and mudstone (Edie, 1958; Harris et. al., 1966; Crabtree, 1982; Kent, 1984 and 1987; Olbelenus, 1985; Waters and Sando, 1987a; Lindsay, 1987; Crass, 1987; Witter, 1988; Petty, 1988; Luther, 1988; Perras, 1990; Valvik, 1990; Lake 1991; Potter, 1995). The Frobisher Evaporite overlies the Frobisher-Alida beds. Previous descriptions and interpretations of the Frobisher-Alida beds although not in complete agreement conform to a shallowing upwards model (James, 1979) as exemplified by modern carbonate peritidal environments (e.g. Persian Gulf, Purser, and Evans 1973; and the Bahamas, Bathurst, 1975). This paper follows the terminology of Witter (1988) in which individual lithofacies are grouped into three shallowing upward environments: open marine, restricted marine, and evaporitic. Eight carbonate and evaporite lithofacies are recognized (Table 2.2) and in the following 25 Depositional Lithofacies Environments Anhydrite: Rust red and white massive anhydrite appx. 1-2 metres thick. salina evaporitic Coated grain: Pisoid, peloidal, ooid grainstone to wackestone, interbedded with 1 mm to 2 cm thick intervals of finely (< 1mm) laminated lime mudstone. high-energy intertidal/shoal Peloidal grainstone: Very fine-grained peloids with a grapestone texture. low-energy intertidal to subtidal/ protected lagoon Skeletal grainstone: Bimodal grain size; fine to medium-grained unidentifiable angular skeletal grains and coarse identifiable fragments of rugose coral, brachiopods, and gastropods. moderate-energy intertidal/ protected lagoon restrited marine Dolomudstone: Massive, mottled, finely (< 1mm) laminated; commonly stained red. low-energy intertidal/tidal flat restrited marine Lime mudstone: Light tan chalky appearance and texture. Ortonella algae is a common component. low-energy intertidal to subtidal/ protected lagoon Bioclastic grainstone: Consists of whole and broken pisoids, ooids, crinoid ossicals, other echinoderm fragments, brachiopod fragments, foraminifera, phylloid algae, bryozoan, and intraclasts. The facies is commonly laminated with dips of 10 to 20 degrees. high-energy intertidal/ tidal channel Crinoid: Interbedded crinoidal grainstone and crinoidal mud to wackestones. Syringopora and fenestrate bryozoa are also present. high-energy/ storm sedimentation open marine Table 2.2: Recognized carbonate and evaporite lithofacies descriptions. The lithofacies are grouped into three broad depositional environments: 1) evaporitic; 2) restricted marine; and 3) open marine. 26 sections are described, interpreted and group into one of the three depositional environments. Frobisher-Alida carbonate and evaporite lithofacies: Crinoid: The crinoid lithofacies is composed of crinoidal grainstone intervals (Fig. 2.11) up to 12 metres thick. Thin grainstone intervals (5 cm) occur interbedded with thick (15 metres) crinoidal mud and wackestone (Fig. 2.11). Contacts between grainstone and mudstone intervals are both gradational and sharp. Allochems present are crinoid ossicles, Syringopora and fenestrate bryozoa. The metre thick scale crinoid grainstone intervals have previously been interpreted as bank or mound deposits" subject to moderate wave energy which winnows out mud and causes transport and accumulation of sand to pebble size crinoid fragments (Kent, 1987; Perras, 1990). Perras (1990) interpreted the thin crinoid grainstone intervals as small debris flow deposits derived from the flanks of adjacent crinoid grainstone banks. However, Fuzesy (1966) interpreted the thin centimeter scale crinoid grainstone beds as storm deposits in which mud was winnowed during high-energy storm events leaving a grainstone lag deposit behind. Gagan et al. (1990) sampled pre and post storm (Cyclone Winifred, February 1st, 1986) shelf sediments in northeastern Australia. Their (op cit) study indicated shelf mud was winnowed and transported leaving a coarse skeletal basal lag, which provides a modern analog for Fuzesy's (1966) interpretation. The heterotrophic filter feeding crinoids are dependent on the active 27 Figure 2.11: Lithofacies of the open marine environment. A ) Core photograph of the crinoidal grainstone; from well 9-12-8-4 W2,1211 m. B) Core photograph of the crinoid mudstone and wackestone; from well 5-18-8-3W2,1204.5 m. 28 circulation of nutrient rich waters (Martindale and Boreen, 1997) best provided in the open marine environment where a combination of both daily wave activity and periodic storm events influenced sedimentation. Coated grain: The coated grain lithofacies is a pisoid dominated, peloid, and ooid grainstone to wackestone, with grainstone as the dominant texture (Fig 2.12). The lithofacies has abundant fenestral and interparticle porosity. The pisoids are on average 2-5 mm, but range up to 15 mm in diameter. Thin intervals (1 mm to 2 cm) of finely (< 1 mm) laminated lime mudstone is interbedded with the grainstone. The lithofacies is laterally extensive in the study area and is interbedded with most other lithofacies. Ooid grainstone up to 7 metres thick rarely occur. There are no good modern analogs for pisolite. However, the well exposed Permian Reef Complex offers an unparalleled opportunity to examine a pisolite lithofacies which has been interpreted as paleo-topographic highs in the outer shelf region, formed in a peritidal environment subject to periodic sub-aerial exposure (Estaban and Pray, 1983). By analogy with the shelf crest pisolite of the Permian Reef Complex The coated grain lithofacies in the Frobisher-Alida beds has commonly been interpreted as a shoal or shelf crest deposit (Edie, 1958; Harris et. al., 1966; Gerhard et. al. 1978; Crabtree, 1982; Kent, 1984; Waters and Sando, 1987a; Lindsay, 1987; Petty, 1988; and Perras, 1990). The fenestral porosity of the Frobisher-Alida coated grain lithofacies possibly created by desiccation and shrinkage during periodic exposure (Choquette and Pray, 1970) also suggests the coated grain lithofacies formed as a topographic highs or shoals on the ramp. 29 Figure 12: Lithofacies of the restricted marine environment. A) Core photograph of the coated grain lithofacies; FP=fenstral porosity, Lm=lime mudstone; from well 4-33-5-1W2,1207.5 m. B) Microphotograph of the coated grain lithofacies; P=pisoid, Pel=peloids; from well 4-33-5-1W2,1208.5 m. C) Core photograph of the dolomudstone lithofacies; M=mottled texture, H=red strain, from hematite; from well 13-13-8-6W2,1181.5 m. D) Photomicrograph of the dolomudstone lithofacies; Q-quartz; D=dolomite; H=hematite; 13-13-8-6W2,1182.5 m. E) Core photograph of the bioclastic grainstone lithofacies; from well 8-6-3-32W1,4084 ft. F) Photomicrograph of the peloidal grainstone lithofacies; Pel= peloids; from well 6-20-5-33Wl, 1147.0 m. 30 Dolomudstone: The dolomudstone lithofacies is predominantly mottled and characterized by a red hematite staining (Fig. 2.12). The mudstone is also massive, finely (< 1mm) laminated, and with rare occurrences of broken tabular laminae 2-3 mm thick. Other colors present are tan, gray, and green. The lithofacies forms laterally extensive (correlative over 10 km) intervals typically 1-2 metres thick. Quartz grains are also a common component especially near contacts with the Kisbey Sandstone (Fig. 2.12). The dolomudstone lithofacies is interpreted as a tidal flat mudstone based on the geometry, mottled texture and dolomitization. Laterally extensive and bioturbated mudstone is typical of intertidal flat environments (Shinn, 1983). Tidal flats are likely to be dolomitized by an evaporitic sabkha reflux hydrology due to the close proximity of the two environments. The evaporitic sabkha reflux dolomitization model is further supported by oxygen isotope data from equivalent dolomudstone intervals in North Dakota, which indicate the dolomite is enriched in SO 1 8 (Elliot, 1987). Elliot (1987) interprets the enrichment of 5 0 1 8 to indicate an evaporitic source of the dolomitization fluids. Bioclastic grainstone: The bioclastic grainstone lithofacies is characterized by a highly varied grain type, consisting of whole and broken pisoids, ooids, crinoid ossicles, other echinoderm fragments, brachiopod fragments, foraminifera, phylloid algae, bryozoa, and intraclasts. The only structures present are planar laminations with depositional dips 10° to 20° (Fig. 2.12). This lithofacies comprises NE-SW trending intervals restricted to the southeastern part of the study area. The bioclastic grainstone is interpreted as tidal channel deposits. Evidence for a tidal influence is the variable grain 31 type indicating transport and mixing of different sediment types. The restricted lateral extent along a NE-SW trend, normal to the paleo-shoreline, is the expected orientation of major tidal channels. Lime mudstone: The lime mudstone has a distinct light tan chalky appearance. Allochems consist of solitary rugose corals and Ortonella algae, which occur as individual fragments and compose thin beds up to 5 cm thick. This lithofacies forms a laterally extensive interval in the south-central part of the study area and is rare elsewhere. Peloidal grainstone: The peloidal grainstone consists of very fine-grain peloids, making hand sample identification and description difficult. The grains have a grapestone texture in which grain contacts and edges are not readily observed (Fig. 2.12). This lithofacies is occurs throughout the study area where it is commonly interbedded with the coated grain lithofacies. Skeletal grainstone: The skeletal grainstone lithofacies has a bimodal grain size distribution. The rock is predominately composed of fine to medium-grained unidentifiable angular skeletal grains. The coarse mode of the rock is composed of rugose coral, brachiopods, and gastropods in decreasing order of abundance. The lime mudstone, peloidal grainstone, and skeletal grainstone lithofacies are commonly interbedded with each other and with the coated grain shoals. The lime mudstone, peloidal grainstone and skeletal grainstone lithofacies are interpreted to occur along the protected flanks of coated grain shoals and comprise a lagoon environment. 32 Anhydrite: Most of the anhydrite intervals are comprised of red and white massive beds, 1-2 metres thick (Fig 2.13). The massive anhydrite is commonly in contact with the coated grain lithofacies. Petrographic textures of the anhydrite consist of felty and laminated textures. Other thicker (30 metres) anhydrite intervals in wells 8-6-3-32W1 and 16-34-7-6W2 have bedded, mosaic (chicken wire) and enterolithic structures (Fig 2.13). Anhydrite intervals with mosaic (chicken wire) structure indicating displacement of a carbonate matrix (Warren and Kendall, 1985) are interpreted as sabkha evaporite deposits (Waters and Sando, 1987; Obelenus, 1985; Lindsay, 1987; Kent, 1984). The massive anhydrite however, shows no evidence of displacement or replacement of carbonate host sediment and is commonly in contact with the coated grain lithofacies which suggests a more basinward environment of deposition than a sabkha. The massive structure and lateral position on the ramp suggest deposition as a subaqueous evaporite. Restricted marine water behind coated grain shoals may have developed into salinas or tidal ponds of Waters and Sando (1987) allowing for the deposition of massive anhydrite. 2.6.3 Depositional environments of the Frobisher-Alida ramp: The open marine and evaporitic environments are composed of single lithofacies, the crinoid and anhydrite lithofacies respectively. The remaining lithofacies, coated grain, dolomudstone, bioclastic grainstone, lime mudstone, peloidal grainstone, skeletal grainstone, comprise the restricted marine environment, which is defined as broadly 33 Figure 2.13: Lithofacies of the evaporitic environment. A) Core photograph of massive anhydrite; from well 16-12-7-5W2,1252.2 m. B) Core photograph of bedded anhydrite; from well 8-6-3-32W1, 3918 ft. C) Core photograph of mosaic (chicken wire) anhydrite; from well 16-35-3-33W1, 3790 ft. D) Core photograph of anhydrite with entrolithic structures; 16-34-7-6W2,1280 m. 34 synonymous with the intertidal zone and includes lithofacies that were deposited in slightly more saline and protected environments than open marine conditions but less restricted and saline than necessary for evaporitic conditions. Such an interpretation is suggested by the periodic exposure indicated by fenestral porosity in the coated grain lithofacies, low biological abundance and interbedded anhydrite (salina) lithofacies. The six lithofacies of the restricted marine environment are variably interbedded with each other (Table 2.1). The apparent non-uniform interbedding of lithofacies suggest that instead of distinct lithofacies belts parallel the shoreline, the various depositional environments are arranged as a mosaic across the ramp (Fig. 2.14). 2.6.4 Depositional Environments of the Kisbey Sandstone: Due mainly to the paucity of sedimentary structures, it is difficult to interpret the depositional environments of the Kisbey Sandstone based solely on the sandstone sedimentology. Only by incorporating the previously described and interpreted carbonate sedimentology with the Kisbey Sandstone sedimentology at three localities within the study area are sandstone depositional environments recognized. The three localities and depositional environments are sandstone shoals (Kisbey Pool), storm generated/reworked sandstone (Areola Pool), and tidal channel sandstone (southeastern part of the study area) (Fig. 2.4). Sandstone shoal/Kisbey Pool The Kisbey Sandstone and crinoidal grainstone are the oil producing lithofacies in the Kisbey Pool (Sturrock et al., 1990). The vertical sequence of lithofacies is complex, 35 36 due to lateral discontinuity of sandstone and dolomudstone intervals. In the Kisbey Pool, the Frobisher-Alida beds are divisible into three informal units (Fig 2.15). The basal unit is composed of open marine crinoidal grainstone (only observed in wells 15-6-8-5 W2 and 4-23-8-6W2). Unit 2 is a complicated unit with two oolitic lithofacies unique to the Kisbey Pool. The base of unit 2 is composed of dolomudstone and laterally equivalent thin (3 metres) oolitic grainstone in which the ooid nuclei are composed of Kisbey Sandstone quartz grains. Upwards the abundance of quartz decreases and the ooilitic grainstone grades to a sandy ooid-echinoid grainstone. The ooids in the sandy ooid-echinoid grainstone form with quartz and carbonate nuclei. The upper portion of unit 2 is composed of the reservoir Kisbey Sandstone (5-10 m) and dolomudstone lithofacies. The reservoir Kisbey Sandstone is truncated to the northeast by the sub-Mesozoic unconformity (Fig. 2.16), it laterally thins and pinches out into the dolomudstone lithofacies to the west and southeast, and thins toward the central portion of the pool (Fig 2.17). The sandstone is planar cross bedding with forset dip from <10° to 30°. The lower contact of the reservoir Kisbey Sandstone interval is gradational with the dolomudstone lithofacies and sharp with the ooid/echinoid dominated grainstone. The upper contact is with a dolomudstone and coated grain lithofacies. This contact is sharp and in some cores marked by a stylolite. Unit 3 is composed of the restricted marine coated grain lithofacies with some localized tidal flat dolomudstone, oolitic intervals and Kisbey Sandstone. Interpretation: The Kisbey Sandstone at the Kisbey Pool is interpreted as a wave influenced sandstone shoal located at the transition between the restricted and open marine environments. The oolitic intervals provide evidence of wave influence. The low-37 <p S B SJ I 1 8 I -a 1 8 | | | a E S a. a 5 | 40 m-Q 1 D G | Kisbey Sandstone coated grain crinoid oolitic grainstone with Kisbey Sandstone quartz grain nuclei sandy ooid-echinoid grainstone dolomudstone sub-Mesozoic unconformity 0 m Q ] \ Q n 1 \J U'V. '3 5 2 ^ N •* * . " ** i l l ;'"'-K" rSlmk 1 1 -© © 1 Figure 2.15: Composite stratigraphic column of the Frobisher-Alida beds developed from described cores at the Kisbey Pool. Three informal units are recognoized: 1) open marine crinoid lithofacies; 2) restricted marine limestone, Kisbey Sandstone and dolomudstone lithofacies; and 3) restricted marine coated grain lithofacies. 38 l—i d +-o 5 C/l 05 tn O o 2 §> 'I p C/5 o e . 2 CO o _o -o c CO o o CM c/i JZ o C3 a, o CD a tN <<2 0 39 r 40 m L 0 m 9 Km datum ' \ l J l . . - •-, • 1 ' i . v- J J'-,*^" t:^ ,:-!. I — © 1 © © © 1 © © © ft — 1 0 L 1 0 L GR Pe N/D Son 0 150 0 1045 -15300 100 cored interval Kisbey Sandstone dolomudstone i " i coated grain crinoid sub-Mesozoic unconformity sandy ooid/echinoid grainstone Figure 2.17: Stratigraphic cross section through the Kisbey Pool. Datum is a gamma ray spike. 40 angle lamination of the sandstone also reflects the influence of waves in the swash zone. The stratigraphic position of the Kisbey Sandstone between the underlying crinoid lithofacies and the overlying coated grain shoals (units 1 and 3) marks a transition between the restricted and the open marine environments. This region is the location on the ramp in which the influence of waves on sedimentation would be the greatest. Perras (1990) proposes a similar interpretation of the Kisbey Sandstone Lost Horse Hi l l field located 25 kilometres northwest of the study area. Storm sandstone/Areola Pool There are two Kisbey Sandstone intervals present at the southwestern part of the Areola Pool. The upper sandstone is preserved only in well 9-13-8-6W2 on an erosional high on the sub-Mesozoic unconformity (Fig. 2.18). The restricted lateral extent makes interpretation of the upper sandstone interval difficult. The lower sandstone is laterally and stratigraphically bounded by the open marine crinoid lithofacies. The sandstone interval is laterally equivalent to a crinoid grainstone interval to the northeast, thins to the southwest and is erosionally truncated to the southeast by the sub-Mesozoic unconformity (Fig. 2.19). The sandstone is predominantly massive but some high-angle (20°-25°) laminated sandstone and mottled intervals occur. The lower contacts of the sandstone and equivalent crinoidal grainstone are sharp with some load and flame structures (Fig. 2.18). Interpretation: The lower Kisbey Sandstone interval in the southwestern part of Areola Pool is interpreted as a storm deposit. The Kisbey Sandstone interval is laterally and stratigraphically bounded within the open marine crinoid lithofacies provides a 41 42 43 perplexing lithofacies association not observed elsewhere in the study area. Previous interpretations (Fuzesy, 1966) indicate storms have affected sedimentation in the open marine environment. Only by association of the Kisbey Sandstone with the storm and wave influenced open marine crinoid lithofacies, the sandstone speculated to have been susceptible to storm activity and transported from the restricted marine environment to the open marine environment during a storm event or events. Once transported to the open marine environment the Kisbey Sandstone would have been susceptible to daily wave activity on the open marine ramp (Kent; 1987; Perras, 1990). Tidal channel sandstone/Southeastern study area Production from the Kisbey Sandstone in the southeastern part of the study area (T3R32W1 to T5R34W1), unlike the Kisbey and Areola pools, is not necessarily associated with structural highs on the sub-Mesozoic unconformity surface. The stratigraphy of the Frobisher-Alida beds in the southeastern part of the study area represents a shallowing upwards sequence from open marine crinoid lithofacies, upwards to restricted marine lithofacies, including the Kisbey Sandstone, and lastly transitioning upwards to the evaporitic environment (Fig. 2.20). There are multiple Kisbey Sandstone intervals present. Up to four Kisbey Sandstone intervals are observed in well 8-6-3-32W1. It is difficult correlate the stratigraphy of all the Kisbey Sandstone intervals observed in core. However two thick (3-20 m) Kisbey Sandstone intervals (referred to as the upper and lower sandstone) can be correlated throughout most of the southeastern part of the study area and are described in more detail. Theses two Kisbey Sandstone 44 \ anhydrite coated grain crinoid .':.>;"J Kisbey Sandstone bioclastic grainstone dolomudstone sub-Mesozoic unconformity Stratigraphy of the NE-SW Kisbey Sandstone trends 2 B «> 8 I S I I I I 1 1 40 m-V ^ n, 1 , I 0m * * * i . • • 5 upper Kisbey Sandstone lower ' . • : : » . ' :J Kisbey : ' ' ' 'Ave/ Sandstone Stratigraphy of areas adjacent to the NE-SW Kisbey Sandstone trends where thick sandstone intervals do not occur 2 I « 8 40 m 11 -2 © © © © © 0m _ © \ 7 V ) 7 v V L 1 . A 1 1 J * *n W\ - h Q Q <> Q a Q 0 D Q Q 0 a a Q evaporitic uncorrelative Kisbey Sandstone restricted marine 0 a \ a a © © open marine Figure 2.20: Composite stratigraphic columns of the Frobisher-Alida beds observed in core from the southeastern part of the study area. 45 intervals comprise NE-SW sandstone trends. The sequence of lithofacies along the NE-SW Kisbey Sandstone trends, is characterized by stacked sequences of sandstone or bioclastic grainstone with the dolomudstone lithofacies (Fig 2.20). The lower Kisbey Sandstone occurs in all three sandstone trends, averaging 5 metres thick with a maximum of 7 metres. In areas where the thick Kisbey Sandstone intervals are not present, the lower sandstone intervals are laterally equivalent to the dolomudstone lithofacies (Fig 2.21). The lower sandstone has sharp lower and gradational upper contacts and is characterized by high-angle laminations (20°-30°). The upper Kisbey Sandstone occurs in two of the NE-SW sandstone trends is a maximum of 17 metres thick and averages 10 metres thick. In areas perpendicular to the NE-SW trends, the upper Kisbey Sandstone is laterally equivalent to the coated grain lithofacies (Fig. 2.21). The upper Kisbey Sandstone has gradational upper and lower contacts and is characterized by planar cross bedding (10°-20°) and parallel lamination. Interpretation: The Kisbey Sandstone located in the southeastern part of the study area is interpreted as tidal channel sandstone. The NE-SW orientation of the Kisbey Sandstone intervals, approximately perpendicular to the paleo-shoreline (Kent, 1987), is the expected orientation of major tidal channels. The association of the tidally influenced bioclastic grainstone with the Kisbey Sandstone along the same NE-SW sandstone trends further suggests a tidal influence on the Kisbey Sandstone deposition. The dolomudstone lithofacies, previously interpreted in this paper as a tidal flat deposit, also occurs with the sandstone and bioclastic lithofacies of the NE-SW sandstone trends. The stacked sequence of the two clastic lithofacies (Kisbey Sandstone and bioclastic grainstone) with the dolomudstone lithofacies indicates a period of channel filling which eventually 46 47 develops into a tidal flat environment, followed by reactivation of the tidal channel. The stacking of tidal channels (Fig 2.22) is possibly controlled by the topography of the underlying sediments. For example, coated grain shoals will act as topographic highs on the ramp that force tidal currents around and between them. Consequently, as the coated grain shoals aggrade and prograde, tidal currents will be constrained within narrow zones over time creating a stacking pattern. The reactivation of similar sedimentation controlled by paleo-topography has been documented on the shallow carbonate shelf on the coast of Belize (Esker et. al. 1998). Finally, the inter-shoal area is the most likely area for tidal influence and preservation. Therefore the position of the Kisbey Sandstone and bioclastic lithofacies, laterally adjacent to the coated grain shoals, further suggests a tidal influence on the Kisbey Sandstone deposition. 2.7 Discussion 2.7.1 Sea level control, incised valley fill and siliciclastic influx'. The drop in sea level interpreted by Witter (1988) and Read and Dorobek (1993) to have occurred during deposition of the Frobisher-Alida beds is also recognized within the study area. However, the drop in sea level did not caused incision of the Frobisher-Alida ramp and deposition of the Kisbey Sandstone as incised valley fill within the study area, but only produced a regression of the restricted marine environment. The following sections firstly review the evidence for a drop in sea level to have occurred during deposition of the Frobisher-Alida beds. Secondly the incised valley interpretation is refuted based on a comparison of the Kisbey Sandstone sedimentology with the characteristic features of incised valleys. 48 4-12-4-33W1 sharp contact Thin (3cm) dolomudstone mud interval ''tb" .'/w. yyy J 1166 1170 1180 gradational contact| sharp contact sharp contact sharp contact gradational contact — I I-l-~H , 1-4 1190 1200 Interpretation Watrous Formation tidal flat mudstone tidal channel unit tidal flat mudstone tidal channel unit tidal flat mudstone tidal channel unit /// Kisbey Sandstone parrallel lamination planar / / / crossbedding bioclastic grainstone dolomudstone Triassic red siltstone and sandstone Figure 2.22: Stacked clastic-dolomudstone sequences 49 Lastly a discussion of eolian transport is presented as an alternative mechanism to a drop in sea level to explain the influx of siliciclastic sand into the carbonate environment. Sea level control In an outcrop study of Frobisher-Alida beds equivalent to that of strata from the shelf margin, located outside of the Williston basin in present day Idaho and Montana, Reid and Dorobek (1993) interpret a type 2 sequence boundary based on a shift of restricted marine sediment basinward over open marine sediments. Their (op cit) type 2 sequence boundary (their SB2[B]) correlates with: 1) the boundary of composite biozones 11 and 12 of Sando (1985); 2) a drop in sea level on the eustatic sea level curve of Ross and Ross (1987); and 3) the K - l marker of Harris et al. (1966) in the North Dakota portion of the Williston Basin. The K - l marker occurs within the Frobisher-Alida beds in North Dakota but is not recognized in Saskatchewan. Reid and Dorobek's (1993) correlations suggest a drop in eustatic sea level occurred during deposition of the Frobisher-Alida beds Similarly, Witter (1988) documented the K - l marker as a surface in which restricted marine sediment significantly shifts basinward over open marine sediment and interpreted this regression to be caused by a relative drop in sea level. Witter (1988) also recognized a Kisbey Sandstone interval in North Dakota as equivalent to the K - l marker, which subsequently led to the interpretation of the Kisbey Sandstone as an incised valley fill deposit. Based on the construction of composite stratigraphic sections in the Kisbey Pool and southeastern localities within the study area, an upward lithofacies transition from the 50 open marine crinoidal grainstone lithofacies to restricted marine lithofacies is recognized (Fig. 2.23). This lithofacies transition marks a similar surface of basinward progradation of the restricted marine environment documented by Witter (1988) in North Dakota and Reid and Dorobek (1993) in an outcrop study of equivalent Frobisher-Alida strata from the shelf margin, located outside of the Williston Basin in present day Idaho and Montana. The Kisbey Sandstone in the study area occurs stratigraphically above the open marine sediment, which indicates the Kisbey Sandstone is only part of the prograding restricted marine package of sediment. If a drop in relative sea level was the primary cause of Kisbey Sandstone deposition, the development of incised valleys would be a likely indicator. A comparison of the Kisbey Sandstone sedimentology in the study area with incised valley characteristics will show the Kisbey Sandstone is not incised valley sediment, which indicates the drop in relative sea level during deposition of the Frobisher-Alida beds did not directly influence the deposition of the Kisbey Sandstone. Incised Valleys Zaitlin et al. (1994) recognizes four characteristics that can be used to identify incised valleys: 1) the valley is an erosional paleo-topographic low in which the base of the valley truncates the underlying strata and any regional markers; 2) the erosional base of the incised valley is correctable with an unconformable surface outside the incised valley. The erosional base of the incised valley may be mantled by a pebble lag and/or characterized by the Glossifungites ichnofacies. The unconformable surface 51 Kisbey Pool s g g s I l l s IJJ J 40 m _^ \~7 \ anhydrite 0 coated grain crinoid bioclastic grainstone Kisbey Sandstone southeastern part of the study area I H i Pit 40 m _, 53 oolitic grainstone with Kisbey Sandstone quartz grain nuclei f I * j ooid-echinoid 2 3 ^ ifM grainstone HI I dolomudstone sub-Mesozoic unconformity 0m >' 8 ' l»v.J!^ 0m J r .','ti« 1 1 \ © © 0 7 \ restricted marine environment open marine environment Figure 2.23: Composite stratigraphic columns of the Frobisher-Alida beds from cores and cross sections through the Kisbey Pool and the southeastern part of the study area showing a similar transition from the open marine to restricted marine environment. 52 outside the incised valley may be characterized by soil or rooted horizon; 3) the basal contact of the incised valley is a contact of landward facies over basinal facies; and 4) markers within the valley fill, onlap the incised valley walls. The elongate geometry of the Kisbey Sandstone in the southeastern part of the study area is consistent with an incised valley geometry; however, the sedimentologic characteristics are absent. The possible incised valley walls do not truncate stratigraphic marker beds. For example, dolomudstone intervals are correlated from within the area of the Kisbey Sandstone trends (possible incised valley fill) to the adjacent coated grain shoal areas (interfluve areas) (Fig. 2.21). Secondly, evidence of an erosional contact at the base of the Kisbey Sandstone, characterized by a pebble lag and Glossifungites ichnofacies is absent and soil or rooted horizons have not been recognized in the possible interfluve areas. However, it may be erroneous to interpret the base of the Kisbey Sandstone intervals as the basal contact of an incised valley because the bottom contact of the entire clastic sequence (sandstone and bioclastic lithofacies) has not been observed in core. Thirdly, the Kisbey Sandstone is ultimately derived from the landward margin of the basin corresponding to the third characteristic of incised valleys namely the valley fill is a landward facies occurring over more basinward facies. Fourthly, marker beds within the possible incised valley fill sediment (i.e. sandstone trend sediment) which would truncate against the valley walls do not exist. The dolomudstone intervals which are, correlated from the areas of possible valley fill sediment (sandstone trends) to the interfluve areas (coated grain shoals adjacent to the Kisbey Sandstone) provide the most conclusive evidence that the NE-SW trending Kisbey Sandstone and associated carbonate 53 lithofacies are not incised valley fill sediment. The fall of relative sea level interpreted by Witter (1988) and Reid and Dorobek (1993) during the deposition of the Frobisher-Alida beds does not incise the Frobisher-Alida ramp and control the deposition of the Kisbey Sandstone within the study area. Siliciclastic influx Eolian transport of sands provides an alternative hypothesis to sea level fluctuation as a controlling mechanism for the influx of the Kisbey Sandstone onto the carbonate ramp. The southeast coast of Qatar provides a potential modern analog. Northwest winds blow offshore along the southeast coast of Qatar causing the migration of siliciclastic sand dunes into the Persian Gulf (Shinn, 1973). The migrating dunes are interpreted to have advanced the shoreline seaward at a rate of 1-2 m/year, and sea level is interpreted to have remained constant at its current elevation during the progradation of the shoreline (Shinn, 1973). Here, the availability of siliciclastic sands and the orientation of the predominant wind direction are the only controls on the influx of siliciclastic sediment onto the carbonate shelf. The plausibility of eolian transport of the Kisbey sandstone to the edge of the Frobisher-Alida ramp is supported by Martindale and Boreen (1997) who argue the prevailing wind direction during the Mississippian Period was from east to west across the continent i.e. directed offshore in relation to the northeastern shoreline of the Williston Basin. The climate was arid and conducive to eolian processes. 54 2.7.2 Depositional Model of the Mixed Carbonate-Siliciclastic Frobisher-Alida beds: A complete depositional model of the Kisbey Sandstone must incorporate both allocyclic and autocyclic influences (Fig. 24). The autocyclic influences control the distribution of the Kisbey Sandstone on the Frobisher-Alida ramp. The reciprocal sedimentation concept does not readily apply to the Kisbey Sandstone and a drop of sea level only controls the position of three broad prograding depositional environments: open marine, restricted marine, and evaporitic. Eolian transport may be the allocyclic mechanism responsible for the initial influx of siliciclastic sand into the carbonate environment. 2.8 Conclusions Only by incorporation of the carbonate sedimentology associated with the Kisbey Sandstone can depositional environments of the sandstone be interpreted. Three distinct Kisbey Sandstone depositional environments are recognized within the study area. At the Kisbey Pool the Kisbey Sandstone is interpreted as a wave influenced sandstone shoal. The influence of waves is indicated by oolitic intervals and an oolitic sandstone lithofacies associated with the Kisbey Sandstone. The stratigraphic position of the Kisbey Sandstone between the restricted marine coated grain shoals and the open marine crinoid lithofacies indicates the sandstone was deposited at a transition between the two environments where wave influence is likely to have an impact on sedimentation. At the Areola Pool, Kisbey Sandstone is interpreted as a storm derived sandstone. The 55 56 occurrence of the Kisbey Sandstone in the open marine environment as a laterally and stratigraphically bounded sandstone body is perplexing. Storm currents are the most plausible mechanism for transporting the sandstone into the open marine environment. In the southeastern part of the study area, the Kisbey Sandstone is interpreted as tidal channel sands. The NE-SW trends of the sandstone intervals parallel the expected orientation of major tidal channels. The association of the Kisbey Sandstone with the tidal bioclastic deposit, occurring along the same NE-SW trends, provides further support of a tidal influence. The influx of siliciclastic sediment into a carbonate environment requires an allocyclic influence such as a drop in sea level. The influence of sea level did not directly influence the Kisbey Sandstone sedimentation and only influences sedimentation of the Frobisher-Alida beds on a regional scale by causing a shift of the restricted marine environment basinward over sediments of the open marine environment. It is only hypothesized that paleo-winds could act as the allocyclic control on the influx of the Kisbey Sandstone by transporting quartz sand from the arid terrestrial environment to the edge and into the carbonate ramp environment analogous to the southeast coast of Qatar. The distribution of the Kisbey Sandstone was then controlled by autocyclic influences acting on the Frobisher-Alida ramp. 57 2.9 References Cited Bathurst, R. G. C. 1971. Carbonate sediments and Their Diagenesis: Developments in Sedimentology Number Two. Pp. 93-146. Carlson, C. G., and J. A. Lefever. 1987. The Madison, A Nomenclature Review with a Look at the Future, In Fifth International Williston Basin Symposium. C. G. Carlson and J. E. Christopher (Eds.), p. 77-82. Choquette, C. W. and L. C. Pray. 1970. Geologic nomenclature and classification of porosity in sedimentary carbonates. American Association of Petroleum Geologists Bulletin, v. 54. P. 207-244. Crabtree, Harry T. 1982. Lithologic Types, Depositional Environment, and Reservoir Properties of the Mississippian Frobisher Beds, Innes Field, Southeastern Saskatchewan. In: Fourth International Williston Basin Symposium. J. E. Christopher and J. Kaldi (Eds.), p.203-207. Crass, David B. 1987. The Stratigraphy, Petrography, and Diagenesis of the Frobisher-Alida Interval, Mission Canyon Formation (Mississippian), Northern Bottineau and Renville Counties, North Dakota. Unpublished Msc. Thesis, Baylor University. 93p. Edie, Ralph W. 1958. Mississippian Sedimentation and Oil Fields in Southeastern Saskatchewan. American Association of Petroleum Geologist Bulletin, v. 42, p. 94-126. Esker, D., G. P. Eberli, and D. F. Mcneill. 1988. The Structural and Sedimentological Controls on the Reoccupation of Quaternary Incised Valleys, Belize Southern Lagoon. American Association of Petroleum Geologist Bulletin v. 82. p.2075-2109. Esteban, M. and L. C. Pray. 1983. Pisoids and Pisolite Facies (Permian) Guadeloupe Mountains, New Mexico and West Texas. In: Coated Grains. T.M. Peryt (eds.). p. 503-537. Gagan, M., A. Chivas, and A. Herczeg. 1990. Shelf Wide Erosion, Deposition and Suspended Sediment Transport during Cyclone Winfred, Central Great Barrier Reef Australia. Journal of Sedimentary Petrology, v. 60 p. 456-470. Gerhard, L. C , D. W. Fischer and S. B. Anderson; 1991, Petroleum Geology of the Williston Basin, In: Interior Cratonic Basins, American Association of Petroleum Geologist, Memoir 51. p. 507-559. Gerhard, L. C , S. B. Anderson and J. Berg. 1978. Mission Canyon Porosity Development, Glenburn Field, North Dakota Williston Basin. In: The Second Williston Basin Symposium p. 177-188. 58 Gutschick, R. C. and C. A. Sandberg. 1983. Mississippian Continental Margins of the Conterminous United States. In: The Shelfbreak: Critical Interface on the Continental Margins: Society for Sedimentary Geology, Special Publication 33. p. 79-96. Harris, Steven H., C. B. Land, and J. H. McKeever. 1966. Relation of Mission Canyon Stratigraphy to oil Production in North-Central North Dakota. American Association of Petroleum Geologist Bulletin, v. 50, p. 2269-2276. Fuzesy, L. M. 1960, Correlation and Subcrops of the Mississippian Strata in Southeastern and South-Central Saskatchewan. Saskatchewan Energy and Mines, Geological Report no. 51 (reprint 1983). 63p. Fuzesy, L. M. 1966. Geology of the Frobisher-Alida Beds, southeastern and south-central Saskatchewan. Saskatchewan Energy and Mines, Geological Report no. 104. 59 p. James, N. P. 1979. Shallowing Upwards Sequences. In: Facies Models. R. G. Walker (eds.). Geological Association of Canada, p. 109-120. Kent, D. M. 1984. Depositional Setting of Mississippian Strata in Southeastern Saskatchewan: A Conceptual Model For Hydrocarbon Accumulation. In: Oil and Gas in Saskatchewan. J. A. Lorsong and M. A. Wilson (eds.). Saskatchewan Geological Society, Special Publication 7. p. 19-29. Kent, D. M. 1987. Mississippian Facies, Depositional History, and Oil Occurrences in the Williston Basin, Manitoba and Saskatchewan, In: Williston Basin, Anatomy of a Cratonic Basin. Mark W. Longman (Eds.). Rocky Mountain Association of Geologist, p. 157-170. Kiessling, W., E. Flugel, and J. Golonka. 1999. Paleoreef Maps: Evaluation of a Comprehensive Database on Phanerozoic Reefs. American Association of Petroleum Geologist Bulletin v. 83. p.1552-1587. Lake, John H. 1991. Transgressive Cycles In an Overall Shallowing Upwards Sequence, Mississippian, Mission Canyon, Nottingham Unit, Williston Basin, Southeast Saskatchewan. In: Sixth International Williston Basin Symposium. J. E. Christopher and F. M. Haidl (eds.). Saskatchewan Geological Survey, Special Publication 11. 136-141. Lindsay, Robert F. 1987. Carbonate and Evaporite Facie, Dolomitization and Reservoir, Distribution of the Mission Canyon Formation, Little Knife Field, North Dakota, In: Williston Basin, Anatomy of a Cratonic Basin. Mark W. Longman (Eds.). Rocky Mountain Association of Geologist, p. 355-384. Luther, M. R., 1982. Deposition and Diagenesis of a portion of the Frobisher-Alida interval (Mississippian Madison Group), Wiley field, North Dakota. Unpublished Msc. Thesis, The University of North Dakota, 298p. 59 Martindale, W., and T. D. Boreen. 1997. Temperature Stratified Mississippian Carbonates as Hydrocarbon Reservoirs-Example from the foothills of the Canadian Rockies. In: Cool Water Carbonates, N. P. James and J. A. D. Clarke (Eds.). SEPM special publication, 56, p.391-409. Obelenus, Thomas J. 1985. Depositional Environments and Diagenesis of Carbonates and Associated Evaporites, Frobisher-Alida Interval, Madison Group (Mississippian), Williston Basin, Northwestern North Dakota. Unpublished Msc. Thesis. University of North Dakota. 313p. Perras, Greg. 1990. Sedimentological and Reservoir Characteristics of the Frobisher-Alida Beds, Lost Horse Hill Field, Southeastern Saskatchewan. Unpublished Msc. Thesis. The University of Regina. 181p. Petty, D. M. 1988. Depositional Facies, Textural Characteristics, and Reservoir Properties of Dolomites in the Frobisher-Alida Interval in Southwest North Dakota. American Association of Petroleum Geologist Bulletin, v. 72. p. 1229-1253. Potter, Dean. 1995. Paleogeographic Reconstruction of an Arid Coastline, Sherwood Beds, Mission Canyon Formation, Southeast Saskatchewan and North Dakota. In: Seventh International Williston Basin Symposium. L. D. V. Hunter and R. A. Schalla (eds.). Montana Geological Society, Special Publication, p.143-161. Purser, B. H. and G. Evans. 1973. Regional Sedimentation along the Trucial Coast of the southeastern Persian Gulf In: The Persian Gulf, Holocene Carbonate Sedimentation and Diagenesis in a Shallow Epicontinental Sea. B. H. Purser (eds.). p. 212-231. Quilin, Garry. 1987. Models of Subsidence Mechanisms in Intracratonic Basins, and their Applicability to North American Examples, In: Sedimentary Basins and Basin-Forming Mechanisms. C. Beaumont and A. J. Tankard (Eds.). Canadian Society of Petroleum Geologists Memoir 12, p. 436-481. Reid, S. K. and S. L. Dorobek, 1993. Sequence Stratigraphy and Evolution of a Progradational, Foreland Carbonate Ramp, Lower Mississippian Mission Canyon Formation and Stratigraphic Equivalents, Montana and Idaho. In: Carbonate Sequence Stratigraphy: Recent Developments and Application. R. G. Loucks and J. F. Sarg (eds.). American Association of Petroleum Geologist Memoir no. 57. p. 327-352. Richards, B. C. 1989. Upper Kaskaskia Sequence-Uppermost Devonian and Lower Carboniferous. In: Western Canada Sedimentary Basin: a case history. B. D. Ricketts (eds.). Canadian Society of Petroleum Geologist, p. 165-202. Ross, C. A., and J. P. Ross. 1987. Late Paleozoic Sea Level and Depositional Sequences. In Timing and Depositional History of Eustatic Sequences: Constraints on Seismic Stratigraphy. C. A. Ross and D. Haman (eds.). Cushman Foundation for Foraminiferal Research, Special Publication No. 24 p. 137-149. 60 Sando, W. J. 1985. Revised Mississippian Time Scale, Western Interior Region, Conterminous United States. Stratigraphic Notes. United States Geological Survey Bulletin 1605-A. p. 15-26. Saskatchewan Geological Society. 1953. Report of the Committee on the Mississippian Nomenclature. Saskatchewan Geological Society. Schlumberger. 1989. Log Interpretation Principles/Applications. 223 p. Shinn, E. A. 1983. Tidal Flat Environment. In: Carbonate Depositional Environments. P. A. Scholle, D. G. Bebout, and C. H. Moore (eds.). American Association of Petroleum Geologist Memoir no. 33. p. 172-210. Shinn, E. A. 1973. Sedimentary Accretion Along the Leeward Side, SE Coast of Qatar Peninsula, Persian Gulf. In: The Persian Gulf. B. H. Purser (eds.). p. 199-120. Sonnenfeld, M. D. and T. A. Cross. 1993. Volumetric Partitioning and Facies Differentiation within the Permian Upper San Andres Formation of Last Chance Canyon, Guadeloupe Mountains, New Mexico. In: Carbonate Sequence Stratigraphy: Recent Developments and Application. R. G. Loucks and J. F. Sarg (eds.). American Association of Petroleum Geologist Memoir no. 57. p. 435-474. Sturrock, D. L., G. M. Cordell, D. C. Westacott, D. M. Fitzpatrick. 1992. Technology Development Synergy: Kisbey, Saskatchewan - A case History, In: The Integration of Geology, Geophysics, Petrophysics, and Petroleum Engineering in Reservoir Delineation, Description and Management. R. Sneider, W. Massel, R. Mathis, D. Loren, and P. Wichmann, (conveners) p. 373-396. Valvik, J. R. 1990. Depositional Environments, Ichnology and Diagenesis of the upper Frobisher-Alida Beds of the Elkhorn Ranch and Roughrider fields of Western North Dakota Unpublished Msc. Thesis. The University of North Dakota. 21 Op. Warren, J. K. and C. G. Kendall. 1985. Comparison of Sequences Formed in Marine Sabkha (Subaerial) and Salina (Subaqueous) Settings-Modern and Ancient. American Association of Petroleum Geologist Bulletin, v. 69. p. 1013-1023. Waters, D. L. and W. J. Sando. 1987.Depositional Cycles in the Mississippian Mission Canyon Formation, Williston Basin, North Dakota. In: Fifth International Williston Basin Symposium, C. G. Carlson and J. E. Christopher (eds.). Saskatchewan Geological Society, Special Publication 9. P. 123-133. Witter, David N. 1988. Stratal Architecture and Volumetric Distribution of Facies Tracts, Upper Mission Canyon Formation (Mississippian) Williston Basin, North Dakota. Unpublished Msc. Thesis, Colorado School of Mines, 142p. 61 CHAPTER 3: DIAGENETIC DEVELOPMENT OF THE KISBEY SANDSTONE RESERVOIRS, MISSISSIPPIAN, WILLISTON BASIN. 3.1 Abstract In southeastern Saskatchewan, the Kisbey Sandstone is locally a prolific oil producing lithofacies of the Frobisher-Alida beds. Its average porosity is 17% and average permeability is 140 md, although both vary in a seemingly unpredictable fashion. The non-uniform distribution of porosity and permeability is characteristic of most sandstone intervals. Core descriptions, petrographic and scanning electron microscope examination of the Kisbey Sandstone reveal primary interparticle pore filling mineral phases of dolomite and anhydrite. Dolomite is pervasive in the Kisbey Sandstone but due to the abundant intercrystalline porosity of the dolomite the sandstone remains porous and permeable. Anhydrite cement, where present, completely occludes the primary interparticle porosity has a patchy distribution at the core sample scale, and qualitatively correlates with zones of low permeability and porosity. Both dolomitization and anhydrite cementation are interpreted to have occurred during the early marine stage of diagenesis. Dissolution occurred during sub-aerial exposure and development of the sub-Mesozoic unconformity. The dissolution event is responsible for the partial dissolution of anhydrite, patchy occurrence of the anhydrite cement, and creation of solution enlarged secondary porosity. Although the Kisbey Sandstone intervals have a non-uniform distribution of low porosity and permeability zones, most sandstone intervals to have good reservoir potential. 62 3.2 Introduction The Kisbey Sandstone, in the subsurface of southeastern Saskatchewan, has been an oil producing lithofacies since the early 1980's. Recent discoveries (in 1996) in southeastern Saskatchewan (T4R33W1) has lead to renewed interest in exploration for reservoir quality Kisbey Sandstone. Previous work on the Kisbey Sandstone diagenesis is limited to documentation of pore filling mineral phases, dolomite and anhydrite, and mercury porosimetry analysis, which indicates the sandstone has a uniform pore size distribution (Kent et. al., 1988; Perras, 1990). The objectives of this paper are to: 1) describe the porosity and permeability of the Kisbey Sandstone on a regional scale; 2) document the distribution and characteristics of the sandstone diagenetic cements throughout the regional study area; and 3) interpret the timing and origin of diagenetic events (paragenesis) that lead to the current cement distribution and hence porosity and permeability. Core data indicates the range of porosity and permeability values are similar for most Kisbey Sandstone intervals. From core descriptions the type of pore filling mineral phase, dolomite and anhydrite, and the core scale distribution of anhydrite are comparable for most sandstone intervals. There is however one Kisbey Sandstone interval (lower sandstone of the Hastings East trend) which is completely cemented with anhydrite and is impermeable. Correlation of core data with core descriptions indicates the wide range of porosity and permeability values are attributed to the non-uniform arrangement of anhydrite cement. Three diagenetic events are interpreted to have affected the porosity and permeability development of the Kisbey Sandstone, dolomitization, anhydrite cementation, and dissolution. Dissolution is responsible for the non-uniform 63 distribution of the anhydrite cement and creation of Kisbey Sandstone with good reservoir potential. 3.3 Geologic Setting 3.3.1 Stratigraphy: Subsurface Mississippian strata in the northeastern part of the Williston Basin are divisible into informal units termed beds, based on geophysical log markers (Fig. 3.1) (Saskatchewan Geological Survey, 1958; Kent, 1987b; Gerhard et al., 1991). There are many nomenclature schemes in use for Mississippian subsurface stratigraphy (Carlson and Lefever, 1987). This paper uses the nomenclature established by the Saskatchewan Geological Survey (1958). The upward succession of informal beds comprise an overall regressive mega-sequence (Kent, 1987) punctuated with smaller scale regressive and transgressive strata (Harris et. al. 1966). All Mississippian beds are unconformablly overlain by the Triassic Watrous Formation. The Mississippian strata sub-crop at the sub-Mesozoic unconformity producing NW-SE sub-crop trends, along which many of the Mississippian hydrocarbon reservoirs occur. 3.3.2 Frobisher-Alida Sedimentology: The Frobisher-Alida beds occur throughout southeastern Saskatchewan and become undifferentiated from other Mississippian beds west of 104° longitude (west of range 15 west of the 2nd meridian; Fuzesy, 1960). The Frobisher-Alida beds have an average complete thickness of 115 metres and thin to 0 metres to the northeast at the 64 Vi vi Vi > -Kibbey - _ Formation -& 2 a c o C/3 • —N •s r"1 L Charles C Formation • A A A s t Mission _^ Canyon _ Formation— sl k k, k L I I L Lodgepole C Formation ^ •*•••;. Bakken -.FormationV Informal beds in southeastern Saskatchewan Ratcliffe beds Midale beds Frobisher -Alida beds Tilston beds Souns Valley beds Midale beds Frobisher Evaporite I^ HasUngs Evaporite 2ZEZE fclf Sandstones i / . MC-2 marker Tilston beds sandstone and black shale basinal to peritidal limestone and dolomite terrestrial sandstone, siltstone and mudstone Figure 3.1: Stratigraphic column of the Mississippian in southeastern Saskatchewan (left column). Center column is the informal subsurface intervals of the Madison Group (Saskatchewan Geological Survey, 1958) and the column on the right shows other recognized informal units including the Kisbey Sandstone within the Frobisher-Alida beds (Fuezey, 1960). 65 subcrop edge (Fuzesy, 1960). The sedimentology of the Frobisher-Alida beds has been extensively studied (Edie, 1958; Harris et. al., 1966; Crabtree, 1982; Kent, 1984 and 1987; Olbelenus, 1985; Waters and Sando, 1987a; Lindsay, 1987; Crass, 1987; Witter, 1988; Petty, 1988; Luther, 1988; Perras, 1990; Valvik, 1990; Lake 1991; Potter, 1995; chapter 2). The Frobisher-Alida beds were deposited in three depositional environments: evaporitic, restricted marine, and open marine. The evaporitic environment is composed of anhydrite lithofacies interpreted as salina and sabkha deposits. The restricted marine environment is composed of pisolitic-oolitic-peloidal grainstone shoals, lagoonal mudstone and peloidal grainstone, tidal flat dolomudstone, and bioclastic tidal deposits. The open marine environment is composed of crinoidal wackestone and storm influenced crinoidal grainstone (chapter 2). The Kisbey Sandstone is defined as multiple laterally and stratigraphically discontinuous intervals of quartz arenite with minor amounts of feldspar and chert that are regionally uncorrelative. Sandstone thickness ranges from <1 to 20 metres with the thicker intervals (3-20 metres) trending NE-SW. The sandstone is predominantly massive with rare planar cross bedding and parallel laminations. The sandstone occurs within all three of the depositional environments of the Frobisher-Alida beds but is most abundant within the restricted marine environment. Interpreted depositional environments are: tidally influenced channel sands, wave influenced sandstone shoals, and storm derived sandstone in the open marine environment (chapter 2). 66 3.4 Methods Permeability and porosity of the Kisbey Sandstone were compared from two known sandstone producing pools and five mapped sandstone trends (Fig. 3.2) identified in cross sections constructed across the study area (chapter 2). The diagenetic characteristics of the Frobisher-Alida beds were described for 125 cores throughout the study area (Fig 3.2). Interpretations of diagenetic events were supported by petrographic examination of twenty-one thin sections, all treated with alizarin red and one treated with potassium ferricyanide, from nine cored Kisbey Sandstone intervals (Fig 3.2) from which six sample were examined by scanning electron microscopy (SEM). 3.5 Results: Reservoir Properties and Diagenetic Characteristics 3.5.1 Kisbey Sandstone diagenetic characteristics: The Kisbey Sandstone is a very well sorted, fine grained, sub-angular to sub-rounded quartz arenite with minor amounts (<3 %) of feldspar. The quartz grains show little indication of compaction (e.g. grain sutures) and comprise a grain supported framework; however, some grains appear supported by the dolomite and anhydrite (Fig 3.3c). Descriptions of fifty-two cored wells of Kisbey Sandstone and throughout the study area, indicate the interparticle porosity of the sandstone predominantly filled with dolomite, and the abundance of dolomite does not vary significantly between different sandstone intervals or within individual sandstone intervals. The dolomite cement occurs as 5-20 um rhombohedral crystals with abundant intercrystalline porosity; it partially fills 67 '-3 •S S . cd T3 '•5 .S C fi U c -3 CO c n 2 .FT? p iG c/3 <U c n 3 4> u fi 3 i • a > o « cn •B a. o cc *• s g (A >> u X CO 1 cu c o . » < N i i i o r o CO v » -S CO •a cd T3 U tu 11 fi u ^ tu o o ed 73 fa X > GO C/3 CN cn <u OfJ c o <U O s '•O 0 o s i cu 1 § •a -r I i CO cu ^ "° -2 g co fe tu O ^ "S rsi co H Q i ^ W CO I 1 / 3 c2 Q - f i •3 s e CO C VO o o g fi 5 .2 E tu s i CO 2 "9 - <u X cu 68 Figure 3.3: Back scatter SEM images of the Kisbey Sandstone; well 13-13-8-6W2,1187.2 m. Q=quartz, D=dolomite, A= anhydrite and Ex=impregnated epoxy, P=porosity. A) Variable filled interparticle porosity by dolomite cement. B) Higher magnification of image A, showing the intercrystalline porosity of the dolomite. C) The sandstone is predominantly framework supported with a few grains (S) supported by dolomite of anhydrite. 69 the interparticle porosity of the Kisbey Sandstone (Fig. 3.3). A potassium ferricyanide solution did not stain the dolomite, indicating a ferric state of Fe in the dolomite cement (Friedman, 1959). Anhydrite cement always occurs with the dolomite cement, but is less abundant. A patchy anhydrite cement (anhydrite zones approximately 2 cm in diameter) and anhydrite cemented lamina (Fig 3.4) occur sporadically throughout most sandstone intervals. The lower sandstone interval of the Hastings East trend is an exception; it is completely cemented with anhydrite and minor amounts of dolomite. Anhydrite in the Kisbey Sandstone occurs as blocky crystals that completely occlude the original intergranular porosity. The anhydrite is poikilitic with quartz grains and dolomite crystals (Fig. 3.4). Pitted surfaces and the projection of right-angled cleavage surfaces into adjacent pore space are distinct characteristics of some anhydrite crystals located at the fringe of patchy anhydrite zones (Fig. 3.4). 3.5.2 Kisbey Sandstone reservoir properties: In the Kisbey Sandstone porosity averages 17% and permeability averages 140 md. However, throughout most cored sandstone intervals the range of porosity and permeability values is extreme. Typical porosity values range from 2% to 24% and permeability ranges from <1 md to 600 md (Fig. 3.5). The distribution of porosity and permeability within a single core is seemingly unpredictable (Fig. 3.5). Due to the homogeneity of the Kisbey Sandstone, grain sorting and mineralogy do not control the porosity, permeability and porosity distribution. Typical permeability and porosity values, including the wide range, are similar for most Kisbey Sandstone intervals 70 20 \xm 20 nm Figure 3.4: Characteristics of anhydrite cement. Q=quartz; A=anhydrite, D=dolomite. A) Core photo of the Kisbey Sandstone showing patchy zones of anhydrite cement (A); well 4-12-4-33W1,1177.6 m. B) Core photo of the Kisbey Sandstone with anhydrite (A) occurring along some lamina; well 13-13-8-9 W2,1160 m. C) Photomicrograph of the Kisbey Sandstone with poikilitic anhydrite around quartz grains; crossed polar; well 15-12-8-4W2,1187.4 m. D) Backscatter SEM image of the Kisbey Sandstone with poikilitic anhydrite around dolomite; well 4-13-6-2W2,1180.6 E) Secondary electron SEM image of an anhydrite crystal with pitted surface; well 4-12-4-33W1,1179 m. F) Secondary electron SEM image of anhydrite crystal with a right angle crystal edges projecting into the pore space (arrow); well 4-12-4-33W1,1179 m. 71 well number Om 4-12-4-33 Wl 10m~J Om 8-27-5-2W2 0 m 16-7-6-2W2 10 m-1 Om 2-13-8-4W2 -10 m-1 Om 15-12-8-4 W2 10m-i permeability (md) 0.1 1 10 100 1000 10000 0.1 I J L Om 10 m-10 100 _ J 1000 10000 Om-10m-J 1 0 M 0.1 1 10 100 1000 10000 Om-0.1 1 10 J L 100 _ J 10 m 1000 10000 n i i 0 m 10 m 0.1 1 10 100 1000 10000 . i i 0 m 10 m-porosity % 10 20 30 10 10 10 10 20 30 3 " 20 _ j 20 L 30 20 30 30 Figure 3.5: Permeability and porosity plots of select Kisbey Sandstone intervals. Throughout the Kisbey Sandstone intervals the permeability and porosity vary in a seemingly unpredictable fashion over a wide range. 72 throughout the study area (Fig 3.6); therefore locality and depositional environment does not appear the control the permeability and porosity either. 3.6 Discussion 3.6.1 Origin and timing of the Kisbey Sandstone diagenetic events: Dolomitization: Interpretation of the origin of the dolomite in the Kisbey Sandstone is highly problematic. The fine (5-20 um) rohmbehedral dolomite crystals that partially infill the interparticle porosity with out any perceivable pattern (i.e. the dolomite is not isopachous) offers little to base interpretations on. Purser et al. (1994) suggest that a precursor calcite with a high density of crystal nucleation cites, such as a lime mud, will produce a microcrystalline dolomite as long as dissolution is minimal during dolomitization. The fine crystalline (5-20 um) dolomite in the Kisbey Sandstone may be a replacement of a lime mud precursor originally deposited with the Kisbey Sandstone quartz grains. A likely source of the precursor lime mud is from the dolomudstone lithofacies commonly associated with the Kisbey Sandstone (chapter 2). To complete the interpretation of the dolomite origin, a hydrolpgic model needs to be evoked. Extensive anhydrite deposits (Frobisher and Hastings Evaporites) located landward of the Frobisher-Alida ramp suggest dolomitizing pore water was likely derived through an evaporitic/sabkha reflux hydrology (Adams and Rhodes, 1960) Dolomitization is interpreted to have occurred in the early marine stage (eogenetic realm) of diagenesis. The limited compaction of quartz grains suggests compaction of the sandstone was minimized by early marine cementation. Dolomite is the likely early 73 6^ co 8 o fe 30 25 20 15 10 o 8 o _fi_ o o o o 9 o o o o o o co cj (50 * <fe ffiw^feOti<s^5 Figure 3.6: Permeability and porosity plots for various Kisbey Sandstone reservoirs and sandstone trends. The plots indicate the variable permeability and porosity values are characteristic of sandstone intervals throughout the study area. 74 marine pore filling mineral phase, which prevented significant compaction from occurring. The ferric state of Fe in the dolomite indicates an oxygenated environment of formation, which further suggests early marine dolomitization. The dolomudstone lithofacies commonly in contact with the Kisbey Sandstone is also interpreted to have been dolomitized in an early marine stage of diagenesis based on enrichment of 50 1 8 reported by Elliot (1987). Anhydrite cementation: The poikilitic anhydrite with dolomite may be a replacement of the dolomite with anhydrite. However, replacement of dolomite with anhydrite is difficult to explain in light of previous research which indicates sulfate is an inhibitor of dolomitization (Baker and Kastner, 1981). Even reversing the standard interpretation of a poikilitic texture, by interpreting dolomite as replacing the anhydrite, is not a convincing interpretation because dissolution of anhydrite during replacement would release sulfate back into the pore water and inhibit dolomitization. The poikilitic texture in the Kisbey Sandstone does not allow for a clear interpretation of the relative timing of dolomitization and anhydrite cementation. Anhydrite cementation is interpreted to have occurred in the early marine (eogenetic realm) stage of diagenesis. The anhydrite cement is likely related to the Frobisher and Hastings Evaporites that were forming landward of the Frobisher-Alida ramp. The same evaporitic marine waters depositing evaporites in the sabkha environment, through an evaporitic reflux hydrology, precipitated gypsum in the porosity of the Kisbey Sandstone as evaporitic groundwater flowed through the Frobisher-Alida sediments. 75 Dissolution: Pitted surfaces and projection of right-angled cleavage surfaces of anhydrite crystals into adjacent pore space (Fig. 3.4) are characteristic dissolution features (Schenk and Richardson, 1985). These dissolution characteristics are observed along the fringe of patchy anhydrite zones (Fig. 3.4) observed in core, which indicates the current seemingly random distribution of anhydrite is caused by dissolution. The timing of the dissolution event can only be broadly constrained as have occurred after dolomitization and anhydrite cementation and before oil migration into the Mississippian reservoirs (Late Cretaceous; Kendall and Walters, 1977). The influx of meteoric groundwater through the Frobisher-Alida beds during exposure and development of the sub-Mesozoic unconformity surface (Triassic) is a likely cause of dissolution (Wetmore, 1983; Elliot, 1987). 3.6.2 Paragenetic development of the Kisbey Sandstone reservoirs: A summary of the diagenetic events that have affected the Kisbey Sandstone is given in figure 3.7. Dolomitization and anhydrite cementation of the Kisbey Sandstone occurred during the early marine stage of diagenesis. Dolomitization reduced the primary interparticle porosity and permeability of the sandstone but due to the abundant intercrystalline porosity of the dolomite the sandstone remained porous and permeable. The anhydrite cement has decreased the porosity of the Kisbey Sandstone by completely occluding the primary interparticle porosity. Dissolution of the anhydrite cement created the non-uniform distribution of the anhydrite cement and increased the porosity and permeability of the Kisbey Sandstone. Dissolution is the key event that created Kisbey 76 CC 3 w <l> O ' £ O "a "s 0 S ? £ !3 ^ a a d u o B W — CD C R CD St fl w 5 a 5 o w p § i a CD i> c Q £ t « M c « O ii cn *. i &« a -Q s co * & CD cn g o> 3 +3 .a A S A S 83 fs M c S a S 5 | | a | 1.11 a w a co uj O O QH a n o o cn cn b -o CD u CD 2 ' a o CD CD B «D « .a I 2 £ I s H 3 w B . s i M a l.sac C+H O CD cn >- l - l CD CD , CL, % IP 8*8 CD o CD 'C -a t =3 CJ CD O CD | 1 CD cn CL CD « OJ oj § IT3 C CD O « CD S a ^ CaO o .2 CD CD M o cf P 5 CD -a CD CD "O N e CD O ,CD CD e CD cn •— CD CD 3 I CD 5 "5 e .a CD I CD -C ¥3 o e o o I a CD c n Q. & c3 II CD g W 2 2 CD '•+-. C o 0 to 1 ! <s i i s ft, cn .SP 1/5 it, -3 CD a I, a -o RJ a " to eg CD cn * DD II t co CO 0 X co u O j -S ^  I oj O CD 5 CO > i> h IH CD M i l II ^ cn 77 Sandstone intervals with good reservoir potential and affected most sandstone intervals throughout the study area except the lower sandstone interval of the Hastings East trend. The lower sandstone interval of the Hastings East trend contrasts with most sandstone intervals because the anhydrite cements the entire interval. An explanation of this uncommon characteristic is linked to the sedimentology of the sandstone interval (Fig, 3.7). Initial dolomitization was not extensive because of insufficient abundance of a calcite precursor (lime mud). The calcite precursor is not abundant because the lower sandstone of the Hastings East trend is not in contact with a dolomudstone lithofacies (chapter 2) from which the original lime mud was derived. Without significant dolomitization occurring, anhydrite was able to fully cement the entire sandstone interval, creating a non-porous and impermeable rock. Subsequent dissolution of the anhydrite was minimized by the lack of permeability for migration of dissolving fluids. The same diagenetic events that have effected most of the Kisbey Sandstone intervals have also effected the lower sandstone of the Hastings East trend, but to different degrees with distinctly different reservoir properties as the end result. 3.6.3 Predictability of reservoir properties of the Kisbey Sandstone: Precise correlation and quantification between permeability, porosity and the cements is difficult due to the small-scale, non-uniform distribution of anhydrite. However, low porosity and permeability values are qualitatively correlative with zones of abundant anhydrite (Fig 3.8). Regionally (throughout the study area) the comparable range of permeability and porosity, (Fig. 3.4) and consistently similar cement type and distribution suggest the same sequence of three diagenetic events had a regional effect on 78 PQ < the Kisbey Sandstone. Due to the similarity of porosity, permeability, cement type and distribution in most sandstone intervals, a prediction of where sandstone intervals with poor versus good reservoir potential will occur can not be made. However, most Kisbey Sandstone intervals are considered to have good reservoir potential because of the similarities of porosity, permeability, cement type and distribution with the prolific oil producing sandstone interval (cumulative production of 1302 x 103 m3 of oil from 1985 to 1998) at the Kisbey Pool. 3.6.4 Conclusions: Low permeability and porosity of the Kisbey Sandstone qualitatively correlates with the core sample scale non-uniform distribution of anhydrite cement. The timing and origin of three diagenetic events can explain the variation of anhydrite cement that characterizes most of the sandstone intervals. Early marine dolomitization and anhydrite cementation occurs first decreasing and rearranging the primary interparticle porosity, followed by incomplete dissolution during exposure and development of the sub-Mesozoic unconformity. Dissolution is the key event responsible for the creation of Kisbey Sandstone intervals with good reservoir potential. The resultant average porosity and permeability of the Kisbey Sandstone is 17% and 140 md respectively, with porosity ranges from 2% to 24% and permeability ranges from <1 md to 600 md. 80 3.7 References Cited Adams, J. E. and M. L. Rhodes. 1960. Dolomitization by Seepage Refluxion. American Association of Petroleum Geologist Bulletin, v. 44 p. 1912-1920. Baker, P. and M. Kastner. 1981. Constraints on the Formation of Sedimentary Dolomite. Science, v. 213. p. 214-216. Carlson, C. G., and J. A. Lefever. 1987. The Madison, A Nomenclature Review with a Look at the Future, In Fifth International Williston Basin Symposium. C. G. Carlson and J. E. Christopher (Eds.), p. 77-82. Choquette, C. W. and L. C. Pray. 1970. Geologic nomenclature and classification of porosity in sedimentary carbonates. American Association of Petroleum Geologists Bulletin, v. 54. P. 207-244. Crabtree, Harry T. 1982. Lithologic Types, Depositional Environment, and Reservoir Properties of the Mississippian Frobisher Beds, Innes Field, Southeastern Saskatchewan. In: Fourth International Williston Basin Symposium. J. E. Christopher and J. Kaldi (Eds.), p.203-207. Crass, David B. 1987. The Stratigraphy, Petrography, and Diagenesis of the Frobisher-Alida Interval, Mission Canyon Formation (Mississippian), Northern Bottineau and Renville Counties, North Dakota. Unpublished Msc. Thesis, Baylor University. 93p. Edie, Ralph W. 1958. Mississippian Sedimentation and Oil Fields in Southeastern Saskatchewan. American Association of Petroleum Geologist Bulletin, v. 42, p. 94-126. Elliott, T.L. 1987. Carbonate Facies, Depositional Cycles, and the Development of Secondary Porosity During Burial Diagenesis: Mission Canyon Formation, Hass Field, North Dakota. In: Williston Basin, Anatomy of a Cratonic Basin. Mark W. Longman (Eds.). Rocky Mountain Association of Geologist, p.385-405. Friedman, G. M. 1959. Identification of Carbonate Minerals by Staining Methods. Journal of Sedimentary Petrology, v. 29 p. 87-97. Gerhard, L. C , D. W. Fischer and S. B. Anderson; 1991, Petroleum Geology of the Williston Basin, In: Interior Cratonic Basins, American Association of Petroleum Geologist, Memoir 51. p. 507-559. Harris, Steven H., C. B. Land, and J. H. McKeever. 1966. Relation of Mission Canyon Stratigraphy to oil Production in North-Central North Dakota. American Association of Petroleum Geologist Bulletin, v. 50, p. 2269-2276. 81 Fuzesy, L. M. 1960, Correlation and Subcrops of the Mississippian Strata in Southeastern and South-Central Saskatchewan. Saskatchewan Energy and Mines, Geological Report no. 51 (reprint 1983). 63p. Kendall, A. C , and K.L. Walters. 1977. The age of metasomatic anhydrite in the Mississippian reservoir carbonates, southeastern Saskatchewan. Canadian Journal of Earth Science, v. 15. p. 424-430 Kent, D. M. 1984. Depositional Setting of Mississippian Strata in Southeastern Saskatchewan: A Conceptual Model For Hydrocarbon Accumulation. In: Oil and Gas in Saskatchewan. J. A. Lorsong and M. A. Wilson (eds.). Saskatchewan Geological Society, Special Publication 7. p.19-29. Kent, D. M. 1987. Mississippian Facies, Depositional History, and Oil Occurrences in the Williston Basin, Manitoba and Saskatchewan, In: Williston Basin, Anatomy of a Cratonic Basin. Mark W. Longman (Eds.). Rocky Mountain Association of Geologist, p.157-170. Kent, D. M., F. M. Haildl, and J. A. MacEchern. 1988. Mississippian Oilfields in the Northern Williston Basin. In: Occurrence and Petrophysical Properties of Carbonate Reservoirs in the Rocky Mountains Region. S. M. Goolsby, and M. W. Longman (Eds.), p. 381-418. Lake, John H. 1991. Transgressive Cycles In an Overall Shallowing Upwards Sequence, Mississippian, Mission Canyon, Nottingham Unit, Williston Basin, Southeast Saskatchewan. In: Sixth International Williston Basin Symposium. J. E. Christopher and F. M. Haidl (eds.). Saskatchewan Geological Survey, Special Publication 11. 136-141. Lindsay, Robert F. 1987. Carbonate and Evaporite Facies, Dolomitization and Reservoir, Distribution of the Mission Canyon Formation, Little Knife Field, North Dakota, In: Williston Basin, Anatomy of a Cratonic Basin. Mark W. Longman (Eds.). Rocky Mountain Association of Geologist, p. 355-384. Luther; M. R., 1988, Deposition and Diagenesis of a portion of the Frobisher-Alida interval (Mississippian Madison Group), Wiley field, North Dakota. Unpublished Msc. Thesis, The University of North Dakota, 298p. Obelenus, Thomas J. 1985. Depositional Environments and Diagenesis of Carbonates and Associated Evaporites, Frobisher-Alida Interval, Madison Group (Mississippian), Williston Basin, Northwestern North Dakota. Unpublished Msc. Thesis. University of North Dakota. 313p. Perras, Greg. 1990. Sedimentological and Reservoir Characteristics of the Frobisher-Alida Beds Lost Horse Hill Field, Southeastern Saskatchewan. Unpublished Msc. Thesis. The University of Regina. 181p. 82 Petty, D. M. 1988. Depositional Facies, Textural Characteristics, and Reservoir Properties of Dolomites in the Frobisher-Alida Interval in Southwest North Dakota. American Association of Petroleum Geologist Bulletin, v. 72. P. 1229-1253. Potter, Dean. 1995. Paleogeographic Reconstruction of an Arid Coastline, Sherwood Beds, Mission Canyon Formation, Southeast Saskatchewan and North Dakota. In: Seventh International Williston Basin Symposium. L. D. V. Hunter and R. A. Schalla (eds.). Montana Geological Society^  Special Publication, p.143-161. Purser, B. H., A. Brown, and D. M. Aissaoui. 1994. Nature, Origins and evolution of porosity in dolomites. In: Dolomites. B. H. Purser, M. Tucker, and D. Zenger (eds.). International Association of Sedimentologist, special publication No. 21. P. 283-308. Saskatchewan Geological Society. 1953. Report of the Committee on the Mississippian Nomenclature. Saskatchewan Geological Society. Schenk, C. J., and R.W. Richardson. 1985. Recognition of interstitial anhydrite dissolution: A cause of secondary porosity, San Andres Limestone, New Mexico, and Upper Minnelusa Formation, Wyoming. The American Association of Petroleum Geologist Bulletin, v. 69, p. 1064-1076 Valvik; J. R.. 1990. Depositional Environments, Ichnology and Diagenesis of the upper Frobisher-Alida Beds of the Elkhora Ranch and Roughrider fields of Western North Dakota Unpublished Ms. Thesis. The University of North Dakota. 210p. Waters, D. L. and W. J. Sando. 1987.Depositional Cycles in the Mississippian Mission Canyon Formation, Williston Basin, North Dakota. In: Fifth International Williston Basin Symposium, C. G. Carlson and J. E. Christopher (eds.). Saskatchewan Geological Society, Special Publication 9. P. 123-133. Wetmore, M. J. 1994. Diagenetic Controls of Reservoir Quality in the Mississippian Wayne Beds in the Williston Basin, Bottineau County, North Dakota. Unpublished Msc. Thesis, University of North Dakota. 209p. Witter, David N. 1988. Stratal Architecture and Volumetric Distribution of Facies Tracts, Upper Mission Canyon Formation (Mississippian) Williston Basin, North Dakota. Unpublished Msc. Thesis, Colorado School of Mines, 142p. 83 CHAPTER FOUR: CONCLUSIONS 4.1 Sedimentology and Depositional Model for the Kisbey Sandstone The Kisbey Sandstone is a massive fine-grained quartz arenite that comprises multiple laterally and stratigraphically discontinuous NE-SW trending intervals, which are only locally correlative. Three distinct Kisbey Sandstone depositional environments are recognized within the study area: 1) at the Kisbey Pool the Kisbey Sandstone is interpreted to be a wave influenced sandstone shoal; 2) at the Areola Pool the Kisbey Sandstone is interpreted as a storm deposits; and 3) in the southeastern part of the study area the Kisbey Sandstone is interpreted as tidal channel sands. Allocyclic processes are necessary to transport siliciclastic sands into the carbonate producing environment. The impact of sea level does not obviously control the deposition of the Kisbey Sandstone and only influences sedimentation of the Frobisher-Alida beds on a regional scale by causing a shift of the restricted marine environment basinward over sediments of the open marine environment. The initial influx of the Kisbey Sandstone into the carbonate environment is controlled by allocyclic process, which is hypothesized to be eolian transport of the sandstone, analogous with the southeast coast of Qatar. However, autocyclic influences (i.e. storms, waves, and tides) controlled the distribution of the sandstone across the Frobisher-Alida ramp once the Kisbey Sandstone arrived. 4.2 Diagenesis of the Kisbey Sandstone Both anhydrite and dolomite cement the Kisbey Sandstone. The two cements are not mutually exclusive at the core sample or microscopic scale as indicated by the 84 poikilitic anhydrite with dolomite. Dolomite is the predominate cement in the sandstone and its abundance does not vary significantly from one sandstone interval to the next. The anhydrite is secondary in abundance to the dolomite and occurs sporadically in individual sandstone intervals as patchy zones and along laminations. The two obvious diagenetic events, dolomitization and anhydrite cementation, are interpreted to have occurred during the early marine stage of diagenesis. Pitted surfaces on anhydrite crystals and right-angled cleavage surfaces of anhydrite crystals projecting into pore space provide evidence for dissolution (Schenk and Richardson, 1985). These dissolution features were observed at the edges of patchy anhydrite zones in the Kisbey Sandstone. Dissolution is interpreted to have incompletely dissolved the anhydrite cement during exposure and development of the sub-Mesozoic unconformity, creating the current apparent random distribution of anhydrite cement. The low permeability and porosity values of the Kisbey Sandstone only reflect the variable distribution of anhydrite cement at the core sample scale. Dissolution is the key event responsible for the creation of Kisbey Sandstone intervals with good reservoir potential. The similarities of reservoir properties and diagenetic features of most sandstone intervals indicate diagenetic events had a regional wide affect on the Kisbey Sandstone and newly discovered sandstone intervals will likely have similar reservoir properties. 4.3 Future Research Directives A defined stratigraphy not only provides a framework for understanding changes in sedimentation through time, but also provides a tool for exploration. A stratigraphy of the Kisbey Sandstone intervals would significantly assist further exploration of potential 85 Kisbey Sandstone reservoirs. However, correlation of the Kisbey Sandstone intervals proved to be difficult due to erosion of some intervals by the sub-Mesozoic unconformity, poor stratigraphic marker control (i.e. most wells do not penetrate the basal marker (MC-2) of the Frobisher-Alida beds), a limited number of wells with a full geophysical log suite suitable for sandstone identification, and the discontinuous nature of the sandstone. A Kisbey Sandstone stratigraphy may be developed by either examination of core and geophysical logs across a regional area at a greater density than achieved in this thesis or the development of a high-resolution bio stratigraphy of the Frobisher-Alida beds, which could then be used to correlate sandstone intervals. Sando (1985) developed a composite biozones stratigraphy for Mississippian strata in the western interior of the United States of America, which may be adaptable to the Frobisher-Alida beds in southeastern Saskatchewan. The provenance of the Kisbey Sandstone is currently unknown. The mineralogy of the Kisbey Sandstone (97-100 (%) quartz) makes provenance analyses difficult. However in the few Kisbey Sandstone samples examined with the SEM indicates the feldspar grains observed were perthite, which may be a distinct and characteristic of the Kisbey Sandstone, which could then be used to correlate with a provenance source. Possible provenance sources are either the Canadian Shield, or older siliciclastic strata in the Williston Basin, such as the Bakken Formation, which may have been exposed at the basin margins during the Mississippian (Kent, 1998 personal communication). 86 4.3 References Cited Kent, D. M. 1998. personal communication Sando, W. J. 1985. Revised Mississippian Time Scale, Western Interior Region, Conterminous United States. Stratigraphic Notes. United States Geological Survey Bulletin 1605-A. p. 15-26. Schenk, C. J., and R.W. Richardson. 1985. Recognition of interstitial anhydrite dissolution: A cause of secondary porosity, San Andres Limestone, New Mexico, and Upper Minnelusa Formation, Wyoming. The American Association of Petroleum Geologist Bulletin, v. 69, p. 1064-1076 87 APPENDIX 1: GEOPHYSICAL LOG ANALYSIS Log signatures of the Kisbey Sandstone intervals: Well 4-12-4-33W1: Two sandstone units occur in the cored interval. The correlative gamma ray signature for both sandstone intervals has higher values than over and underlying limestone. The photoelectric index values range between 2.5 to 4 with the higher values occurring at the contacts. The photoelectric adsorption for quartz is 1.6 to 1.8 (Slumburger, log manual, 1989); therefore the photoelectric values correlated with the sandstone intervals are effected by cement types, (dolomite, calcite, and or anhydrite) and bed boundaries. One of the more significant indicators of the presence of a sandstone lithology is crossover of the neutron and density logs when calculated with a limestone matrix. The density and neutron logs correlative with both sandstone intervals show crossover of the two curves. The sonic log correlative with the lower sandstone shows two sharp increases of interval transit time. The sonic spike correlated with the lower sandstone interval is indistinguishable from the multiple other sonic spikes on the log. The sonic log correlated with the upper sandstone shows an increase interval transit time relative to the under and overlying limestone in with a spiky character throughout the interval. 88 89 Well 13-13-8-6W2 Two sandstone units occur with in the cored interval. The lower of the two sandstone intervals correlates with decreasing values of the gamma ray log. The upper sandstone has a variable gamma ray response. The gamma ray signature of basal portion of the upper sandstone interval shows two sharp increases, while the upper portion of the sandstone interval is relatively static and slightly higher values than clean under and overlying limestone. There is a lithological variation in the upper sandstone, which explains the variance in the gamma ray signature. The basal portion of the sandstone is mottled with green wispy lamina, while the upper portion is not mottled and with out green lamina. The green lamina (clays) are the probable source of the gamma radiation. The photoelectric values that correlates with the lower sandstone ranges from three to four. The photoelectric values that correlate with the upper sandstone range from 2.5 to 3.2 with the higher values near the bed boundaries. The neutron and density porosity logs are calculated with a limestone matrix. The log signatures that correlate with the lower sandstone show a small amount of cross over and indicate equal values of porosity. The density and neutron curves that correlate with the basal mottled portion of the upper sandstone show some separation. The neutron and density curves that correlate with the un-mottled zone of the upper sandstone show cross over of the curves and indicated equal porosity values. 90 Well4-33-5-lW2 The cored interval contains one thin (0.5 m) sandstone. The correlated gamma ray signature is a single spike to the right. The correlative sonic log signature show an increase in the interval transit time. The sonic response is not distinguishable from the rest of the log. Well 16-22-4-34W1 There are two sandstone units with in the cored interval. The lower sandstone interval contains two thin dolomite intervals, one at the base of the sandstone and one in the middle of the sandstone. The correlative gamma ray signature of the lower sandstone and dolomite interval show an increase relative to the under and overlying limestone. The upper sandstone is a sandy dolomite or a well-cemented sandstone. The gamma ray signature correlative with the upper sandstone shows an increase relative to under and overlying limestone. The sonic log signature correlative with the lower sandstone is variable reflecting the two dolomite intervals (faster interval transit time). The correlative sonic signature of the upper sandstone shows a transition from a slow interval transit time upwards to a faster interval transit time. 92 Well 9-6-7-4W2 The sandstone intervals present in the cored interval are two thin (4-cm and 6-cm) sandstone intervals with in a dolomite interval. The gamma ray signature correlative with the dolomudstone/sandstone shows an increase relative to overlying limestone; however, the increase in gamma ray values is probably caused by the presence of stylolites. The photoelectric log has a value of three, which is the expected value for dolomite. The sandstone intervals are too thin to be picked out using the photoelectric log. The sonic log signature correlative with the sandstone intervals show an increase in the interval transit time. The increase in interval transit time is not distinguishable for other increases on the log. The correlative signature of the neutron and density logs shows an increase in the porosity but there is not any cross over of the curves when calculated with a limestone matrix. Well 16-20-4-33Wl There is one thin (10-cm) thick sandstone unit with in the cored interval. The correlative gamma ray log shows a small increase, which is not distinguishable from other peaks on the gamma ray log. The correlative sonic signature is non-distinct. 95 96 97 Well 1-32-7-4 W2 There is a four metre thick sandstone underlain by a dolomite interval and overlain by a crinodal grainstone. The gamma ray response correlative with the sandstone shows an increase in value relative underlining limestone at the base and decreases upwards through the interval. The sonic log correlative with the sandstone shows variable interval transit time throughout the interval. Log signatures of the carbonate lithofacies: Coated grain lithofacies: Core wells 16-20-4-33W1; 4-33-5-1W2; and 16-22-4-34W1 have coated grain lithofacies with correlative gamma ray values that range from 7-24 API gamma ray units. The gamma ray signature is relatively static throughout the facies. The sonic log signature of the coated grain facies is highly variable. The variability is caused by the occurrence of both porous and anhydrite cemented zones (non-porous) with in the lithofacies. Dolomudstone lithofacies: Intervals (> lm) of dolomite occur in core wells 4-12-4-33W1; 13-13-8-6W2; and 9-6-7-4W2. The gamma ray signature varies form well to well and with in the dolomite intervals. Core well 9-6-7-4W2 shows two sharp increases on the gamma ray log. The lower peak correlates with a stylolite zone, and the upper peak correlates with two stylolites. The gamma ray signature corilative with the dolomudstone in well 13-13-98 99 8-6W2 is non-discript. In well 4-12-4-33W1 the correlative gamma ray values are both high and low. The porosity logs, density and neutron, in all three wells, show separation between the two curves when calculated with a limestone matrix. Lime mudstone lithofacies: The lime mudstone lithofacies is present in core well 9-6-7-4W2. The gamma ray values are relatively low and static, similar to the coated grain facies. The photoelectric log has values that range from 4-5, which is expected for a CaCCh. The porosity logs, sonic, density and neutron, are all relatively static. Crinoid lithofacies: The crinoid facies consist of two lithologies. One is the crinoidal mud to wacke-stones, and the other is crinoidal grainstones. Well 16-12-8-4W2 contains 14-m of cored crinoid facies. The gamma ray log shows an increase correlative with the mud to wackestone interval. The mud to wackestone facies has green wispy lamina (clays) which probable account for the gamma radiation. The granstone intervals correlate with relatively low gamma ray values. The photoelectric log indicates calcite. The density and neutron logs show variable porosity. 100 APPENDIX 2: THIN SECTION DESCRIPTIONS Two wells which where extensively sampled for petrographic examination are grouped together and listed first. The remaining thin sections are grouped together by lithofacies. Example of sample thin section identification: Sample Number: 10 (catalog number)- 1000.2 (depth in metres) Well ID: 10-10-10-10W2 (LSD) Sample Number: I B - 1198.2 Well ID: 13-13-8-6W2 Lithofacies: Oolitic Sandstone Lithologic Description: • QTZ. arenite; QTZ grains are subangular to subrounded; fine sand size; tangential Grain to grain contact is moderate to good; • Carbonate grains consist of mostly ooids; medium sand size; echinoid spines, brachipod fragments, possible phyloid algae? • Minor amounts of ty in rock; moldic and some intercrystalline ty Diagenetic Description: • Minor blocky calcite filling interparticle ty Sample Number: 10 B - 1190.5 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite. QTZ grains are subangular to subrounded; fine sand size. Grain to grain contact is moderate to good; minor feldspar • ty 20-25%; pores are irregular shaped; The irregular sides of pores are formed by dolomite rombs; the edges of the pores are brown (oil stained). 102 Diagenetic Description: • dolomite; microspar; lines interparticle pore walls; also occurs in a few patches larger than the QTZ grains; dolomite crystals are rombehedral. Sample Number: 11B - 1189.9 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite; QTZ grains are subangular to subrounded; fine sand size; tangential grain to grain contact is moderate to good. • <()15-20%; primary interparticle <() is partially infilled with dolomite and where present completely filled with anhydrite. • Reported kmax = 12.2 md (> = 14% Diagenetic Description: • Dolomite; microspar, fills 30% of the primary interparticle (|) • Blocky anhydrite; poikilitic with QTZ; occludes primary interparticle <)> in the locale zone of cementation; poikilitic with dolomite, straight planar contacts with QTZ and irregular rectangular contact with dolomite. Sample Number: 12 B - 1188.8 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite; QTZ grains are subangular to subrounded; fine sand size; tangential grain to grain contact is moderate to good; average sands grain size is FGS but there is a distinct medium sand size fraction; minor amounts of feldspars. • <() 15%- Pore shape (irregular) shaped pores controlled the occurrence of microspar dolomite 103 Measured kmax= 32.9md ty= 16% Diagenetic Description: • Dolomite; microspar; fills ~ 30-40% of the original primary interparticle (j>; irregularly distribution in the pore space • Patchy blocky anhydrite fills primary interparticle porosity; has irregular-rectangular contact with dolomite. Sample Number: 13 B - 1186.8 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite; QTZ grains are subangular to subrounded; fine sand size; tangential grain to grain contact is moderate to poor • Measure ty- 14% Km ax 23.1md Diagenetic Description: • dolomite; microspar fills 70-90% of the primary interparticle ty, crystals are rhombehedral, generally fill primary interparticle ty along the QTZ grain edges. Rare patches where cement is the main component to the rock (i.e. the area of dolomite is larger than the detrital grains.) • Anhydrite; fills 3-5% of primary interparticle ty; 0.3mm blocky crystals that are form-fitting around QTZ grains with a sharp contact; poikilitic with QTZ grains, poikilitic with dolomite crystals. • Minor oil stain. Sample Number: 14 B - 1183.3 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, QTZ grains are subangular to subrounded; fine sand size; tangential grain to grain contact is moderate to poor • .Measured ty: 14% 104 Kmax: 4.45md Diagenetic Description: • dolomite; microspar; fills 70-90% of the primary interparticle cj), dolomite rhombs, generally fill primary interparticle <|> along the QTZ grain edges. Rare patches where cement is the main component to the rock (i.e. the area of dolomite is larger than the detrital grains.) • Anhydrite fills 3-5% primary interparticle (|> as 0.3mm blocky crystals that are form-fitting around QTZ grains with a sharp contact; poikilitic with QTZ grains, poikilitic with dolomite crystals. Sample Number: 15 B - 1182.5 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone; upper contact with dolomudstone Lithologic Description: • The middle section of the TS is a QTZ arenite; QTZ grains are subangular to subrounded; fine sand size; moderate to poor tangential grain to grain contact. • There is change to a dolomudstone across a sharp boundary in which both the QTZ grain size and amount decrease. Average grain size is VFG to silt in dolomudstone. There is still some FG QTZ grains present as well. Hematite occurs as lensoidal zones in the microspar dolomite. Hematite also occurs in the QTZ arenite zone. • No d). Sample Number: 15 BB - 1182.5 Well ID: 13-13-8-6W2 Lithofacies: dolomudstone Lithologic Description: • dolomudstone with VFG silt-sized QTZ grains disseminated throughout. • Black opaque mineral (Hematite) associated with the rust red motteled texture of the dolomudstone. Also has patchy distribution. • No (j) 105 Sample Number: 2 B - 1197.1 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone; contact with sandy ooid echinoid grainstone Lithologic Description: • Transition from QTZ SS with carbonate grains to a sandy ooid echinoid grainstone; QTZ grains are subangular to subrounded; fine sand size; Oolitic QTZ grains are present. • The upper part of the TS is composed of: ooids, QTZ grains, echinoid spines, phyloid algae, brachipod fragments, and possibly bryozoan fragments • Minor moldic ty and minor intercrystalline ty in blocky calcite cement Diagenetic Description: • In the upper carbonate dominated section the primary interparticle ty is filled with blocky calcite • Compaction features (i.e. grain sutures) are not observed • Compaction stylolite separates the carbonate-dominated rock from the QTZ SS dominated rock below • The stylolite is composed mainly of densely packed QTZ with blocky calcite Sample Number: 3 B - 1196.6 Well ID: 13-13-8-6W2 Lithofacies: Ooid grainstone, echinoderm, minor qtz Lithologic Description: • Ooid/echinoderm grainstone: Ooids with carbonate grains and micrite as nuclii; other grains present are echinoderm fragments, echinoderm spines, possible bryozoan fragments, intraclasts of micrite with silt-sized carbonate rhombs and qtz silt; 1 fusinlinid; brachiopod shell fragments, minor amounts of gastropod shells • Minor moldic ty Diagenetic Description: • Blocky calcite fills most of the interparticle and intra/moldic ty. • Anhydrite selectively replaces calcite ooids (outer coating); has rectangular contact with carbonate ooids. Anhydrite also replaces the blocky calcite as evidenced by 106 poikolotopic anhydrite around calcite crystals; has sharp, planar contact with blocky calcite. Sample Number: 4 B - 1195.5 Well I D : 13-13-8-6W2 Lithofacies: Ooid grainstone Lithologic Description: • Ooid/echinoderm grainstone: Ooids with carbonate grains and micrite as nuclii; other grains present are echinoderm fragments, echinoderm spines, possible bryozoan fragments, intraclasts of micrite with silt-sized carbonate rhombs and qtz silt; fusinlinid; brachiopod shell fragments, minor amounts of gastropod shells • Some oollitic qtz grains • Minor moldic dp Diagenetic Description: • Anhydrite shows some fabric selective replacement of grains and some replacement blocky calcite cement replacement. • Both moldic dp and anhydrite filled moldic dp present Sample Number: 5 B - 1194.4 Well I D : 13-13-8-6W2 Lithofacies: Ooid echinoderm grainstone Lithologic Description: • Brachiopod dominated grainstone; ooids with quartz nuclei, echinoid spines and crinoid occicles. • Micritic envelopes obscure grain boundaries. Diagenetic Description: • Micritization appears relatively extensive obscuring grain boundaries. • Blocky calcite fills interparticle and intrapartical dp • minor replacement of carbonate grains by anhydrite • Some of the inner parts of ooids are dolomitized with intercrystal dp 107 Sample Number: 7 B - 1193.9 Well ID: 13-13-8-6W2 Lithofacies: Lower contact of upper Kisbey Sandstone interval Lithologic Description: • Qtz sandstone is present on the top half of the thin section. Qtz grains are subround-subangular fine sand size; moderate to poor tangential grain to grain contacts; minor feldspars • Dolomite in the lower half; microspar; with anastomosing opaque lamina and fine-grain to silt-sized QTZ grains disseminated throughout • There is one large (skeletal) grain present in the QTZ sandstone section that is replaced with bladed anhydrite (Possible crinoid fragment) Diagenetic Description: • After dolomite the anhydrtie is the predominant cement type. • In the sandstone section anhydrite occurs as patchy blocky crystals within the dolomite • Anhydrite; rectangular contacts with dolomite Sample Number: 72 B - 1187.2 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subround-subangular fine sand size; moderate to poor tangential grain to grain contacts; minor feldspar • d> 10-15%; pores are irregular lenticular to sphereoidal, slightly smaller than the QTZ grains • Measured O- 16% Kmax= 15md Diagenetic Description: • Dolomite; microspar; fills 70-90% of the primary (j>; Rare patches where cement is the main component to the rock (i.e. the area of dolomite is larger than the detrital grains.) 108 • Anhydrite fills 3-5% of <jms 0.3mm blocky that are form-fitting around QTZ grains; poikilitic with QTZ with sharp contacts; poikilitic with dolomite crystals Sample Number: 8 B -1193 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone; mottled Lithologic Description: • Dolomudstone/Quartz sandtone; QTZ grains are supported by the microspar dolomite. The QTZ grains are subround-subangular fine sand size to very fine sand/silt. • There are patches of an opaque substance throughout thin section (hematite), • No <J>. Diagenetic Description: • Dolomite; microspar Sample Number: 9 B - 1191.1 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone, mottled Lithologic Description: • Dolomudstone/ Quartz sandstone; QTZ grains are subangular to subrounded, fine-grained sand in size and supported by dolomite. • There are some distinct black opaque phase that is associated with the rust red mottled zones in hand sample; hematite. • No d). Diagenetic Description: • Dolomite; microspar 109 Sample Number: 99A - 1198.8 Well ID: 13-13-8-6W2 Lithofacies: Kisbey Sandstone, with ooids Lithologic Description: • 50% Qtz grains and 50% CaC03 grains; poor to moderate tangential grain to grain contact • Qtz grains are subangular to subrounded, medium-grained sand • Oolitic coating on quartz grains; radial fiborous calcite • Carbonate grains consist of mostly ooids; medium sand size; echinoid spines, brachipod fragments, possible phyloid algae? Diagenetic Description: • Faintly fibrous coating on most of the carbonate and detrital grains. Then there is a sharp contact from the isopachous coating to blocky pore filling calcite. • Minor amount of ty; vuggy ty with carbonate grains; some intercrystaline ty Core well 4-12-4-33Wl Sample Number: 41B-1200.9 Well ID: 4-12-4-33W1 Lithofacies: bioclastic grainstone 110 Lithologic Description: • Pisoid grains, whole and broken; crinoid ossicals, and brachiopod fragments; grainstone texture • No dp Diagenetic Description: • All grains are dolomitimized (grains were not stained by alizerine red) • Anhydrite has felty and blocky texture. Sample Number: 42B-1199.5 Well ID: 4-12-4-33W1 Lithofacies: Mudstone Lithologic Description: • Mudstone, dolomitimized Sample Number: 60B-1197 Well ID: 4-12-4-33W1 Lithofacies: bioclastic grainstone Lithologic Description: • Grainstone texture; grains present: intraclasts (micrite with rombehedral dolomite crystals), pisoids, crinoids ossicals, echinoid spines. • Minor <() Diagenetic Description: • Blocky anhedral calcite replaces crinoid grains and fills interparticle <J) • Minor amount of anhydrite with both felty and blocky texture Sample Number: 44B-1195.7 Well ID: 4-12-4-33W1 Lithofacies: Kisbey Sandstone Lithologic Description: 111 • QTZ arenite, Qtz grains are subround-subangular fine sand size; moderate to good tangentenal grain to grain contacts; minor feldspar Diagenetic Description: • Anhydrite and dolomite occur in approximately equal proportions; 50/50 • Anhydrite occurs as blocky crystals; poikilitic with dolomite • Dolomite; micospar; decreases in content upwards into sandstone Sample Number: 62B-1195.7 Well ID: 4-12-4-33W1 Lithofacies: Near lower contact of Kisbey Sandstone Lithologic Description: • Top portion of thin section pisoid grainstone, flatened pisoids; mixed with minor amount of fine grained quartz sand; some crinoid ossicals and brachiopod fragments • Below sharp contact wackestone with unidentified grains which are replaced or filled with anhydrite, matrix is micrite • Trace amounts of d) Diagenetic Description: • Anhydrite replaces grains and matrix material (micrite) Sample Number: 85-1194.8 Well ID: 4-12-4-33W1 Lithofacies: Kisbey Sandstone Lithologic Description: 112 QTZ arenite, Qtz grains are subround-subangular fine sand size; moderate to good tangential grain to grain contacts; minor feldspar Trace amounts of dp Diagenetic Description: • Anhydrite occludes the most of the interparticle dp; poikilitic around quartz • Dolomite; microspar (0.16-0.08 mm long); occurs in a few isolated patches Sample Number: 45B-1193.5 Well ID: 4-12-4-33W1 Lithofacies: bioclastic grainstone Lithologic Description: • Pisoid dominated grainstone, micritized; with QTZ grains 20%; micritized crinoid grains. • Minor moldic and intercrystal dp Diagenetic Description: • Anhydrite, blocky crystals and felty textured; replaces carbonate grains Sample Number: 84-1191 Well ID: 4-12-4-33W1 Lithofacies: bioclastic grainstone Lithologic Description: • Pisoids; occurs as whole, fragmented, and aggregates of pisoids; comprises 20-30% of the rock • Crinoid ossicles, comprise 20% of the rock • Other grain consist of forams, phylloid algae, and echinoderm fragments • intrepartical an intrapartical dp 11 Diagenetic Description: • All porosity is occluded by anhydrite • Minor amount of sytaxial calcite cement Sample Number: 46B-1188.5 Well ID: 4-12-4-33W1 Lithofacies: bioclastic grainstone Lithologic Description: • Ooid/pisoid/skeletal grainstone; dominant grains are pisoids and ooids, some are broken; skeletal fragments consists of brachiopods, echinoid spines with syntaxial overgrowth cement, fusilinids, crinoid ossicles; interaclast are also present • Minor amounts of very fine sand to silt sized QTZ grains; commonly incorporated in the pisoids and ooids. • Minor interparticle ty, minor intrapartical and moldic ty Diagenetic Description: • Some compaction features; sutured grain contacts between coated grains (pisoids and ooids) • Dominant cement type is blocky anhedral calcite filling interparticle ty; syntaxial cement around echinoid grains • Minor blocky anhydrite fills primary interparticle ty • Minor rohbohedral dolomite; microspar; occurs along the walls of pores. Sample Number: 47B-1187.4 Well ID: 4-12-4-33Wl Lithofacies: bioclastic grainstone Lithologic Description: • Ooid/pisoid/skeletal grainstone; dominant grains are pisoids and ooids, in which a few are fragmented; skeletal fragments consists of brachiopods, echinoid spines with syntaxial overgrowth cement, fusilinids, crinoid ossicles; One large (>3mm) interaclast are also present • Minor amounts of very fine sand to silt sized QTZ grains; commonly incorporated in the pisoids and ooids. • interparticle ty and intrapartical ty 114 Diagenetic Description: • Dominant cement type is blocky anhedral calcite filling interparticle ty; syntaxial cement around echinoid grains • Minor blocky anhydrite fills primary interparticle ty; partially replacing carbonate grains (crystals penetrate grain edges) • Minor dolomite; microspar; occurs along the pores walls Sample Number: 59B-1183.6 Well ID: 4-12-4-33W1 Lithofacies: dolomudstone Lithologic Description: • Microspar dolomite • Subangular-subrounded, fine to silt sized QTZ grains • Hematite crystals disseminated throughout Sample Number: 48B-1183 Well ID: 4-12-4-33W1 Lithofacies: dolomudstone Lithologic Description: • Microspar dolomite • Subangular-subrounded, fine to silt sized QTZ grains; comprise 15-20% of the rock • Hematite crystals appear as lamina Diagenetic Description: • Minor rombehedral dolomite crystals (spar size) 115 Sample Number: 86-1182.6 Well ID: 4-12-4-33Wl Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subround-subangular; fine sand size; rare tangential grain to grain contacts • Interparticle <j>; 20% • Minor oil stain Diagenetic Description: • Dolomite; microspar; partially fills interganular (j) • Trace amounts of anhydrite Sample Number: 98-1179 Well ID: 4-12-4-33Wl Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subround-subangular fine sand size; minor tangential grain to grain contacts; minor amount of chert grains • Minor oil stain • Interparticle <j>; 5-10% Diagenetic Description: • Anhydrite is the dominant cement type; completely occludes pores where present • Dolomite; microspar; partially fill interparticle porosity; few instances where the QTZ grains are floating in the dolomite Sample Number: 88-1178.8 Well ID: 4-12-4-33W1 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subround-subangular; fine sand size; minor tangential grain to grain contacts; 116 Diagenetic Description: • Anhydrite completely occludes pores where present • Dolomite; microspar; partially fill interparticle porosity Sample Number: 87-1175.6 Well ID: 4-12-4-33Wl Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subround-subangular fine sand size; tangentional grain to grain contacts are not observed • Interparticle <j>; 10%; moderately interconnected Diagenetic Description • Dolomite is dominant cement; microspar, partially fills interparticle (j) • Minor amounts of anhydrite; has irregular rectangular contact with the dolomite Sample Number: 89-1172.5 Well ID: 4-12-4-33W1 Lithofacies: bioclastic grainstone Lithologic Description: • Pisoid grainstone with minor amounts of crinoid, brachiopod, and interclasts • Interclast have very fine grain sized QTZ grains incorporated in them • No (p 117 Diagenetic Description • All interparticle ty is filled with anhydrite Lithofacies descriptions Sample Number: 57-1252.2 Well ID: 6-12-7-5W2 Lithofacies: massive anhydrite Lithologic Description: • Anhydrite crystals are rectangular; 0.16-0.4 mm by 0.24-0.08 mm; occur massed together with moderate parallel orientation. • Crystals less than 0.04 mm long have a felty texture Sample Number: 39-1247.7 Well ID: 3-2-6-3W2 Lithofacies: Anhydrite Lithologic Description: • Anhydrite crystals have a bladed and block shape • Anhydrite has irregular contact with dolomite (micospar) • Together the anhydrite crystals have both felty texture and blocky (Pile O Brick) textures Sample Number: 76-1227.5 Well ID: 11-28-7-5W2 Lithofacies: massive anhydrite 118 Lithologic Description: • Bladed anhydrite crystals • Felty texture • Both large crystals 0.16-0.4 mm by 0.24-0.08 mm and very small crystals 0.04 mm long of anhydrite Sample Number: 75-1225.3 Well ID: 11-28-7-5W2 Lithofacies: massive anhydrite Lithologic Description: • Micrite sized anhydrite crystals; massive texture • Faint outlines equant rectangular grains observed Sample Number: 41-1212.8 Well ID: 8-24-6-3W2 Lithofacies: massive anhydrite Lithologic Description: • Massive anhydrite; crystals are 0.002 mm in diameter • With in massive anhydrite are larger anhydrite crystals; bladded; up to 0.16 by 0.08 mm; occur throughout • Opaque areas; 0.24 to 0.32 mm long; unknown material; perhaps microspar dolomite Sample Number: 38-1255 Well ID: 12-23-5-3W2 Lithofacies: Kisbey Sandstone/dolomudstone Lithologic Description: 119 • QTZ content varies in thin section from 90% QTZ to areas of <50%QTZ in which the QTZ grains are floating in dolomite microspar. • QTZ grains are subangular-subrounded; fine grain sand; in area if abundant QTZ there is abundant tangential grain to grain contacts • No dp Diagenetic Description • Dolomite; mircospar; fills limited interparticle dp • Single bladed anhydrite crystals; 0.1 to 0.2 mm long, disseminated throughout the dolomite Sample Number: 20-1211.2 Well ID: 4-33-5-1W2 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subround-subangular; fine sand size; moderate tangential grain to grain contacts; minor feldspars • dp ranges from 20-50%; pores in areas of high dp are interconnected and larger than detrital grains Diagenetic Description • Dolomite; microspar; partially fills interparticle dp; in some areas of the thin section zones of dolomite are larger than the QTZ grains Sample Number: 75B-4012.6 Well ID: 8-6-3-32W1 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subrounded-subangular; fine sand size; moderate to poor abundance of tangential grain to grain contacts; minor feldspars • Interparticle dp; 40-50%) 120 Diagenetic Description • Dolomite; microspar; fills 10-20% of the original primary interparticle ty • Anhydrite completely occludes pore were present; poikilitic with dolomite Sample Number: 34B-1212.4 Well ID: 16-22-4-34W1 Lithofacies: Lithologic Description: • QTZ arenite, Qtz grains are subrounded-subangular; fine sand size; moderate to poor abundance of tangential grain to grain contacts; minor feldspars • Interparticle ty; 5-10% Diagenetic Description • Dolomite; microspar; fills 60-80% of the primary interparticle ty; intercrystal ty with in the dolomite; a few zone in which the dolomite cement is larger than the detrital grains • Anhydrite cement fill 2-3% of the primary interparticle ty; blocky and poikilitic with dolomite • Minor calcite cement Sample Number: 32B-1216.7 Well ID: 16-22-4-34W1 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subrounded-subangular; fine sand size; moderate to poor abundance of tangential grain to grain contacts; minor feldspars • Interparticle ty; 5% Diagenetic Description • Dolomite; microspar; fills 60-80% of the interparticle ty; intercrystal ty with in the dolomite; a few zone in which the dolomite cement is larger than the detrital grains • Anhydrite cement occludes interparticle ty where the anhydrite occurs; blocky and poikilitic with dolomite • Minor calcite cement 121 Sample Number: 78A-1187.4 Well ID: 15-12-8-4W2 Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subrounded-subangular; fine sand size; moderate abundance of tangential grain to grain contacts • Interparticle dp; 10% Diagenetic Description • Dolomite; microspar; fills 40% of the primary interparticle dp; intercrystal dp with in the dolomite; a few zone in which the dolomite cement is larger than the detrital grains (QTZ grains float in dolomite) • Minor amount of anhydrite cement; poikilitic around QTZ grains Sample Number: 96-1183.6 Well ID: 2-3-5-34Wl Lithofacies: Kisbey Sandstone Lithologic Description: • QTZ arenite, Qtz grains are subrounded-subangular; fine sand size; poor abundance of tangential grain to grain contacts • Interparticle dp; 5-10% Diagenetic Description • Dolomite; microspar; partially fills of the interparticle dp; intercrystal dp within the dolomite • Minor amount of anhydrite cement; poikilitic around QTZ grains Sample Number: 31-1180.6 Well ID: 14-13-6-2W2 Lithofacies: Kisbey Sandstone Lithologic Description: 122 • QTZ arenite, Qtz grains are subrounded-subangular; fine sand size; poor abundance of tangential grain to grain contacts • Interparticle <j); 10% Diagenetic Description • Dolomite; microspar; partially fills of the interparticle dp; intercrystal dp with in the dolomite • Minor amount of anhydrite cement; poikilitic around QTZ grains and with dolomite • Contacts between the two cements are irregular and sharp Sample Number: 1 Well ID: 4-5-5-33Wl Lithofacies: lime mud Lithologic Description: • Micrite, calcite • Minor amounts of bladed anhydrite Sample Number: 35-1223.4 Well ID: 14-36-5-3W2 Lithofacies: lime mud Lithologic Description: • Micrite, calcite • Minor rombic crystals (dolomite?) scattered throughout the micrite Sample Number: 3-1147 Well ID: 6-20-5-33W1 Lithofacies: peloidal grainstone Lithologic Description: 123 \ • Peloidal shaped grains with grainstone texture • Minor moldic (j) Sample Number: 4-1211 Well ID: 6-15-3-33W1 Lithofacies: peloidal grainstone Lithologic Description: • Peloidal shaped grains with grainstone texture; grains are clumped together to form a grapestone texture; distinction of grain boundaries is difficult because all grains are composed of micrite. Sample Number: 18B-1270.8 Well ID: 9-6-7-4W2 Lithofacies: dolomudstone Lithologic Description: • Micrite; dolomite and calcite indicated by alizerin red stain • Fine to silt sized QTZ grains; comprise 10% of the rock Sample Number: 74B-1220.6 Well ID: 6-2-4-34Wl Lithofacies: dolomudstone Lithologic Description: • Micrite; calcite; rombehedral dolomite crystals (0.04 mm wide) disseminated throughout • Angular QTZ silt disseminated through out thin section • Hematite occurs throughout Sample Number: 76B-4030 Well ID: 8-6-3-32W1 Lithofacies: dolomudstone 124 Lithologic Description: • dolomite; micrite; abundant QTZ, • QTZ grains are subangular; very fine sand size; poor abundance of tangential grain to grain contacts • Hematite is present Sample Number: 29A-1196.6 Well I D : 2-13-8-4W2 Lithofacies: dolomudstone Lithologic Description: • Dolomite; micrite; abundant QTZ; • QTZ grains are subangular; fine sand to silt size; disseminated throughout • Hematite disseminated throughout Sample Number: 92-1208.5 Well I D : 4-33-5-1W2 Lithofacies: coated grain Lithologic Description: • 50 % pisoids and ooids; 30 % peloids; with grainstone texture • interparticle <j>; 20% Diagenetic Description • anhydrite fills all the interparticle (j) Sample Number: 93-1208.5 Well I D : 4-33-5-1W2 Lithofacies: coated grain 125 Lithologic Description: • 50% 2-4 mm pisoids; nuclii are commonly fragments of other pisoids; 40% peloids • interparticle, fenestral, and vuggy ty; 10% Diagenetic Description • Minor amounts of bladed anhydrite occludes pores Sample Number: 94-1170 Well I D : 2-3-5-34W1 Lithofacies: coated grain Lithologic Description: • Pisoid-peloid grainstone • Interparticle, fenestrel, and moldic ty Diagenetic Description • ty partially field with blocky calcite; radiating from the edeges of pore walls Sample Number: 95-1172.5 Well I D : 2-3-5-34W1 Lithofacies: coated grain Lithologic Description: • Pisoid grainstone; pisoids are broken and fractured • Interparticle ty Diagenetic Description • Bladed calcite fills pores from pore wall outward, towards center of pore blocky calcite fill the rest of the pore • Minor amounts of anhydrite 126 APPENDIX 3: T R A C E E L E M E N T ANALYSIS O F T H E ANHYDRITE From petrographic and SEM examination of the Kisbey Sandstone it is apparent that anhydrite cement can significantly effect the reservoir quality of the sandstone by occluding porosity; hence understanding the origin of the anhydrite would provide in-sight as to the regional distribution of this pore filling cement. From the regional subsurface investigation of core, three main anhydrite diagenetic facies have been recognized and presumably one of these anhydrite facies concurrently cemented the Kisbey sandstone. The three anhydrite facies are: 1) massive anhydrite, interpreted to be a shallow water depositional evaporite; 2) vein anhydrite interpreted to be a telogenetic event associated with exposure creating the sub-Mesozoic unconformity (Pennsylvanian-upper Triassic) (Kendall, 1975); 3) brown metasomatic anhydrite described by Kendall and Walters (1977), interpreted to be of Jurassic to Cretaceous in age and associated with oil migration into Mississippian reservoirs. Multiple trace elements were analized for and the stoichiometries of the four anhydrite samples are presented in table 1. Sr was the only trace element that is in concentrations above the detection limit. There is only one significant difference between the weight percent Sr of the different anhydrite facies, which is Sr abundance in the vein anhydrite consistently below the detection limit (Fig; appendix; 1). The Sr abundance alone does not allow for a conclusive correlation between the sandstone anhydrite cement and one of the other anhydrite facies. 127 Table 1 Microprobe analyses of anhydrite: Stoichiometry of select microprobe analysis of the sandstone anhydrite cement and 3 anhydrite facies. Sandstone Brown Anhydrite Massive Metasomatic Vein Cement Anhydrite Anhydrite Anhydrite oxide 31-3 57-4 2-3 42-4 S0 3 58.93 59.63 58.21 60.13 CaO 40.8 40.68 41.69 41.23 Al 2 0 3 0 0 0 0 MgO 0 0 0 0 MnO 0 0 0 0 FeO 0 0 0 0 SrO 0.31 0.18 0.47 0 BaO 0 0 0 0 Sum Oxide 100.04 100.49 100.37 101.36 Figure; appendix; 1: Weight % Sr of all microprobe analysis. Bars show the 20" ranges. Sample 31 = sandstone anhydrite cement, sample 57 = massive anhydrite, sample 2 = brown metasomatic anhydrite, sample 42 = vein anhydrite. Points plotted at 0 weight % were below the detection limit. 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 31-1 31-2 31-3 31-4 31-5 31-6 57-1 57-2 57-3 5 7-4 57-5 57-6 57-7 •57-8 2-1 2-2 2-3 2-4 •42-1 4 2-2 42-3 •42-4 128 APPENDIX 4: CORE DESCRIPTIONS legend for core descriptions lithofacies V V V ' V V VI ISZZ SZ2 SZZ_ Watrous Fromation; Triassic; terrestrial red siltstone and sandstone anhydrite dolomudstone lime mudstone peloidal grainstone skeletal grainstone coated grain bioclastic grainstone crinoid contact type Q gradational S sharp NO not observed ST stylolite structures ^ planar cross bedding ^ parallel lamination A stylolite sandstone diagenetic facies J homogenous pore filling dolomite U patchy anhydrite anhydrite cemeted lamina carbonate diagenetic facies | pore filling anhydrite H porous carbonate; predominantly interparticle porosity; p| also moldic, fenestral and vuggy Kisbey Sandstone veins of anhydrite; oriented from horizontal to vertical; average 0.5 - 2 cm in width; white in color brown anhydrite; irregular contact with carbonate lithofacies; referred to as metasomatic anhydrite in literature chert and limestone noduals well #: 14-22-3-32W1 cored interval (feet): 1132-1144 C L CD T3 J J j i — n 8 diagenesis carb SS description 1135-1140-n c c c c c c c < c < c c < c c c c c c c ( c c c c c c 130 well #: 3-25-3-32W1 cored interval (metres): 1129-1147 C L CD -a o "§ -§ diagenesis = "in 8 carb SS I » I • I l I ° I 7 Z ~ Z description n Q n red stain contact; possable load and flame structure 131 well #: 4-33-3-35W1 cored interval (feet): 1129-1145 CL CD cn _o o co co co — Io 8 diagenesis carb SS description 1130 -1135 -1140 -1145-s n ST thin orange lime mud at contact; grades up to coated grain red stain 132 well #: 8-28-3-32W1 cored interval (feet): 1127-1145 = "K 8 carb SS description diagenesis 1130-1135 H 1140 H 1145-^ 2 G S 133 well #: 8-6-3-32W1 cored interval (feet): 3927-4107 CL CU T3 4070-cn _o o to g> to "g diagenesis "K 8 carb SS E E E E E E E E 4080 -E E E E E E E E 4090-4100-E E E ^ C E I E E E E ^ H EEI l ^- l- r l E E E E E I E E E E I - 1 - H p NO description top of interval grades up to a lime mudstone; which grades up to the sandstone red stain mottled red stain; anhydrite noduals 134 well #: 8-6-3-32W1 cored interval (feet): 3927-4107 CL CO 4030-CD o 4040-4050-4060-4070-E C 3 ^ 1 I3E zzzz i I-^ -I I L 3 SI CO CO 8 G diagenesis ca'rb SS description mottled and red stain rip up clast of dolomudstone; dolomudstone belo contact has brecciated texture gradational through thin zone of peloidal grainstone continued on next page 135 well #: 8-6-3-32W1 cored interval (feet): 3927-4107 description entire sandstone interval is yellow and red stained continued on next page 136 well #: 8-6-3-32W1 cored interval (feet): 3927-4107 CO g- o "§ -2 diagenesis 3950-= "Jo 8 carb SS description 3960-3970-3980 -3990-' V V V| V V V ' V V Vj V V V ' V V Vi V V V ' V v vi V V V " V — v — " V ' V V VI V V V ' V V vi V V V ' V v vi V7 V? V7. 77~yr. G G G G NO NO G red stain; well cemented upper contact obscured by anhydrite noduals interval is stained red sandy (quartz) sandy (quartz) sandy (quartz) continued on next page 137 well #: 8-6-3-32W1 cored interval (feet): 3927-4107 CO -c cn CD 1 3 = s 8 carb £ to o j | diagenesis SS description 3930 - A 3940-3950-— v — v — V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V ' V V V V V V 138 well #: 1-28-3-33W1 cored interval (metres): 1199.3-1217.6 CL CU TD to a? & 3 o o s diagenesis ^ "io 8 carb SS >> o description 1200- I I I V V V V V V \7 V V V V V s V V V V V V ? V V V V V ^ V V V V V V v1 V V V V V ^ V V V V V V ? V V V V V ^ V V V V V V 1205-1210-1215-1 NO thin (10 cm) sandstone; gradational upper and lower contacts 139 well #: 14-10-3-33W1 cored interval (metres): 1204.7-1216 CD CO o co £ Hi — lo 8 diagenesis carb SS description 1205 -1210 • 1215-V V V ' V V v | V V V ' V V vi V V V ' V V V] V V V i ,i : i I I I ' V V VI V V V ' V V VI V / /A s G 140 well #: 15-21-3-33W1 cored interval (metres): 1202-1218 CU TD >s cn o co P CO — "co 8 diagenesis carb SS description 1205-V V V ' V V VI V V V t v v M V V V t V V V| V V V ' V V vi v v v ' V V VI V V V ' V V V| V V V ' V V VI V V V ' V V VI V V V ' V V VI 1210 1215-I I V V s s 141 well #: 6-15-3-33W1 cored interval (metres): 1194.5-1212.7 CL cn o 2? <2 Z3 O "g -§ diagenesis •5 8 carb SS description 1195-1200-1205 -1210 -V V V ' V v vi V V V ' V V Vi V V V ' V V v| V V v ' v v v l V V V ' V V Vi V V V ' V v vi V v v ' V V V] V V V ' V v vi , y y 7 7 7 7 / 7 s G G I I red stain; anhydrite noduals; sandy (quartz) intervals red stain grades up to a 12 cm interval of interbedded sandstone and dolomudstone 143 well #: 16-36-4-1W2 cored interval (metres): 1179.5-1197.5 C L CD "0 CO o n ST diagenesis carb SS description thin (20 cm) dolomudstone with gradational upper an lower contacts thin (10 cm) dolomudstone with sharp upper and lower contacts thin (10 cm) dolomudstone at bas of core; gradational contact up to sandstone 144 well #: 10-4-4-32W1 cored interval (metres): 1122.8-1141.7 CU < D c n "§ & diagenesis = "io 8 carb SS CD O description 1125 h 1130 1135-1140—T 145 well #: 10-11-4-32W1 cored interval (metres): 1093.3-1105.5 CL CU "a •g 2 B to 3 0 o g •§ diagenesis ^ 8 carb SS description 1095-1100-1105-top 15 cm of core is red anhydrite red stain at base of core 146 well#: 13-7-4-32W1 cored interval (metres): 1161-1179 CU X J CO cu es CO o M2 o "G "o =J t_ on —— "oo o carb SS description 1165-1170 -1175-sub-Mesozoic unconformity 147 well #: 14-194-32W1 cored interval (metres): 1128-1146.4 CD T 3 CO CD " O CO O CO fD (O o .2 diagenesis "So 8 carb SS 1130 1135 1140-1145-description 148 well #: 16-29-4-32W1 cored interval (metres): 1103.6-1121.9 03 ' o P> tn g -2 diagenesis "K 8 carb SS description 149 well #: 2-29-4-32W1 cored interval (metres): 1101-1119 g- o g -f diagenesis 7 3 = to 8 carb SS description 1105 — 1110 1115 — 150 well #: 3-29-4-32W1 cored interval (metres): 1111.3-1129.3 •S S ja £ CD =3 O g" o " -§ diagenesis carb SS description 1115-1120 -1125-151 well #: 4-15-4-32W1 cored interval (metres): 1107-1225.3 Q-CD T3 CO o to =3 O "g & diagenesis "io 8 carb SS description 1110-1115 -1120-1125-< < ( ( ( ( ( ( c < < < < ( ( < ( ( ( ( < < < < ( ( ( ( ( ( < < ( ( < < ( c c c c ( c ( c ( ( ( c. ( ( < < < < < < ( ( ( < 152 well #: 9-33-4-32W1 cored interval (metres): 1088.4-1106.7 £ «2 CD TD _ O o 3 diagenesis i = o co u carb SS description 153 well #: 12-24-4-33W1 cored interval (metres): 1142-1155 f» CO => ~Z5 o 3 diagenesis "So 8 carb SS description 1145-sub-Mesozoic unconformity 1155-n G G 1150-m 154 well #: 14-14-4-33W1 cored interval (metres): 1149-1162.2 CL cu T3 CO O CO Z3 O "o J9 = c "to 3 diagenesis carb SS description 1150-1155 —{ 1160 -n n 155 well #: 14-29-4-33W1 cored interval (metres): 1174.3-1182.0 fe £ JQ g- o y is diagenesis carb SS description 1175 Entire interval is an ooid grainstone well #: 16-20-4-33W1 cored interval (metres): 1165-1183 CL cu "O co cu o >2 o CO P CO o s diagenesis "io 8 carb SS description < c ( c < c ( ( ( ( ( ( < < < < ( ( ( ( ( c < < < ( ( ( ( ( ( c ( < c < ( ( c c ( c c ( ( NO c S c ( ( c < ( ( ( ( ( ( < ( ( < ( ( c < 157 well #: 2-25-4-33W1 cored interval (metres): 1143-1161 C O > ; fU to g- -§ o s diagenesis = « 8 carb SS description 1145-1150 —T 1155 —T 1160-n n n n NO well #: 4-11-4-33W1 cored interval (metres): 1190.5-1208.5 CL CU T3 1090-cn o fU CO Z3 " O o .2 diagenesis "lo 8 carb SS description z__z zzzz k / / / z 159 well #: 4-12-4-33W1 cored interval (metres): 1164-1200 CL CD CO CD CJ CO O CO <D CO o -S diagenesis "to 8 carb SS description 1165-k - i - r H " I 1170 -1175-1180-3^1 H I 2 sub-Mesozoic unconformity thin green dolomudstone near top of interval continued on next page 160 well #: 4-12-4-33W1 cored interval (metres): 1164-1200 CU T3 CU " O .2 O 00 2> co 1180-o s diagenesis "K 8 carb SS 1185-^W1 E l—l- l 1190 1195-1200-rar i i — i ra 3 3 LEI n I-H zzz zzz I I—I EES NO description thin dolomudstone interval missing core interval is compleatly cemented with anhydrite 161 well #: 4-24-4-33W1 cored interval (metres): 1140-1150.4 CL CU TD CO & £ "> o g •§ diagenesis ^ ti 8 carb SS description 1140 1145-1150-162 well*: 6-12-4-33W1 cored interval (metres): 1163-1199 x r CD 0) O co 82 <G =3 O "g .2 diagenesis "io 8 carb SS description 1165-1170 • 1175-1180-f V V M V V V ' V V V | V V V rn ^•I-^-I^-I G G sub-Mesozoic unconformity bottom of interval is a skeletal wackestone; with quartz sand; grades up to a packestone texture well cemented thin dolomudstone; green lamina 35 cm thick well cemeted zone; less oil stain continued on next page 163 well #: 6-12-4-33W1 cored interval (metres): 1163-1199 Q. CD T3 CO o <D to ZD tS "S diagenesis 1180-"co 8 ZZ 777 77, /, 1185--I . !-=-! E3 I t —I E T E 1190 E E ft ZEE: E l - I - I — E l - H — I 1195 H E l — ' — I E E E E E carb SS description oil stained quartz sand; increses in abundace upwards green wispy lamina possible brake in core? minor amounts of quartz sand above contact Anhydrite completely cements sandstone interval thin green lamina anhydrite noduals at contact thin green lamina - red stain possible skeletal grains -red stain 164 well #: 15-11-4-34W1 cored interval (metres): 1200-1218.2 a> 1200 -CO o £ B — to 8 1205-1210 -1215-E L " E I E I E i E T I E v v v ' V V V| V V V ' v v M v v v ' y V V, E E E ^ diagenesis carb SS description grades up to anhydrite lithofacies 1.7 metre thick interval of mixed dolomudstone and sandstone with abundant anhydrite noduals red stain; horizontal lamina well #: 16-22-4-34W1 cored interval (metres): 1199.3-1217.6 description red stain; minor amounts of quartz sand lower contact; load and flame structure lower contact; load and flame structure 166 well #: 6-2-4-34W1 cored interval (metres): 1217-1235 to fe 9? J2 ±= g => o g- o g -2 diagenesis 7 3 = "K 8 carb SS description G H top of core; dolomudstone; upwards to skeletal grainstone thin skeletal grainstone at top of interval 4 cm interval of mosaic (chicken wire) anhydrite 7 cm skeletal graistone; bounded by stylolites 167 well#: 10-26-5-2W2 cored interval (metres): 1219-1232 O-CD T3 CO ZZ! o ~ -fc= o CO o s diagenesis carb SS description 1220-1225 -1230 -I I - I W1 1 - T I - 1 - I 5 5 I I I n n I sub-Mesozoic unconformity brown metasomated anhydrite scattered throughout some sandy intervals ooid grainstone micritized pinpoit porosity minor amounts of quartz; climbing ripples 168 well #: 11-23-5-2W2 cored interval (metres): 1219.5-1235.5 CL CD XJ CO o o o "§ -S diagenesis carb SS description 1220 -n 1225 • 1230-n n n n n n n 1235 —r sub-Mesozoic unconformity minor amounts of euhedral calcite partially fill porosity top 1 metre of interval is an ooid grainstone 169 well #: 12-33-5-2W2 cored interval (metres): 1216.4-1234.7 CL CU 1215-o "§ -2 diagenesis s "io 8 carb SS description /VTA 777 77~7. -7777, 7~y NO NO minor amounts of euhedral calcite interbedded coated grain and peloid grainstone lithofacies quartz sand present; decreasing in abundance upwards sandy (quartz) dolomudstone minor amounts of euhedral calcite partially fill pores 30 cm thick dolomudstone interval 170 well #: 14-27-5-2W2 cored interval (metres): 1245.1-1225.6 CL CU "O 1225-co o o £ co =3 tS "g s diagenesis 8 carb SS description 1230 -1235 -1240 -IS 1245-s s I I 171 well #: 4-33-5-1W2 cored interval (metres): 1200.9-1216.1 CD T3 CO CD "o O CO CD CO o .s diagenesis "to 8 carb SS description 1205. 1210-G G G G 1215 —T red stain 172 V well #: 8-27-5-2W2 cored interval (metres): 1215-1233 P to Q . CO "0 1Z o s diagenesis "io 8 carb SS Z i zz rn zzr no zz 777/ description Interval has distict intraclasts composed of pisoids and ooids; interbedded intervals of silt to very-fine-grained peloids brown metasomatic is extensive in the upper 2 metres of the interval; the anhydrite partially fills the poroisty; non-uniform distribution minor amounts of eunedral cacite cement in pores green color at base; minor amounts of quartz interval from 1225.5 to 1226.0; orange stain; grainstone with intraclast of pisoid and ooid; mudstone clasts; grades up to wackestone; finally grading up to dolomudstone mottled mottled 80 cm sandy dolomudstone interval; gradational lower and sharp upper contact 173 well #: 12-30-5-33W1 cored interval (metres): 1121-1132.3 CL CD T3 CO a? m o "§ -2 diagenesis carb SS description top 5 cm of interval; red stained dolomudstone and anhydrite orange stain smalrdisplacive anhydrite noduals 174 well #: 4-19-5-33W1 cored interval (metres): 1131-1149.5 CO T3 CO £ <S 1131 -0 "§ -§ diagenesis 1 "K 8 carb SS 1135. 1140 -1145-_Z2 7 / / ZZZZZ7 =55 IZ I L 3 ZZZZJ izza i • i • i description thin (10 cm) dolomudstone interval dolomudstone interval at contact 175 well #: 4-25-5-34W1 cored interval (metres): 1141.4-1161.2 co fe £ m g - o g |j diagenesis 7 3 = "io 8 carb SS description 1140 — ZZ1 1145-1150 -1155 1160- /777. NO 3 thin (0.5 -1 cm) green mudstone intervals; occures with anhydrite noduals top of beding plane of mudstone has polygonal structure; interpreted as mud cracks minor amounts of quartz sand thin (15 cm) coated grain interval 176 well #: 4-5-5-33W1 cored interval (metres): 1166.4-1185 well #: 6-20-5-33W1 cored interval (metres): 1136-1154 CL TD CO O fO CO ZD tS o .3 diagenesis "So 8 carb SS description ra: ran 1 1 ii I ran nra ran c c ( < c c 178 well #:14-12-5-3W2 cored interval (metres): 1280-1298 CU T 3 CD o CO fU CO 1280-z : 1285 -1290 -1295-n ST n ST G diagenesis carb SS description c c c c c c c §! c/ c/ I s _ I orange stain few pisoid grains wispy green lamina possible load and flame structure at bottom contact Quartz present 179 well #: 14-25-5-3W2 cored interval (metres): 1234.4-1244.4 CD CO a o CD CO Z3 tS ts jS p d J= o CO o diagenesis carb SS description 1235 1240-180 well #: 14-36-5-3W2 cored interval (metres): 1225.9-1244.2 TD co o ZD O "3 J5 1225-diagenesis carb SS description 1230 -1235 -1240-n n H n anhydrite content increases upwards; top 6 cm is chicken wire anhydrite; minor amounts of quartz grains interpartical and fenestral porosity only partialy filled with anhydrite; anhydrite has a non-uniform distribution this interval consist of interbedded intervals of mud and grainy (peloids) intervals few grains of ortenella algae few grains of ortenella algae _ coated grain; brown metasomatic anhydrite some mud intervals 181 well #: 7-36-5-3W2 cored interval (metres): 1235-1253 C L CU 1235 -cn _o o fu ui ZD ~ 0 1240 -1245-1250—^ I - I - I diagenesis carb SS description I _ coated grain moldic/vuggy porosity from 1241-1235 finely laminated pinpoint porosity mottled; red stain; some sandy intervals anhydrite noduals present possible burrows; outline indicated by red stain" 182 well #: 14-13-6-2W2 cored interval (metres): 1174-1192 CL CD T3 <D "o o CO S> CO o B diagenesis 8 carb SS description 1175 _ 1180. i Z i zzz I lyl ZZ • I K-l 1185-1190 -I Z I 3 Z I I S zzz zzz zzz zrc zzz NO NO c c c c c c c c c c c c c c c c c c c c G c c c c £ • sub-Mesozoic unconformity some quartz sand in the stylolite some identifiable crinoid grains porosity is interpartcle and moldic; partially filled with anhydrite 183 well #: 15-16-6-1W2 cored interval (metres): 1173-1191 CD .CO fD to g- •§ o & diagenesis "° = -io 8 carb SS description I izz zzz Z y T , §E 1 1 is z ~ r ~ —. i v — I as I I c c c c c c c c c c c c c c c c c c c c c c top 7 cm is a sandstone red stain at top of interval -184J well ft 15-6-6-1W2 cored interval (metres): 1193-1211 C L CD X J CO CD O o C O CD CO ryn L 3 3 1 3 1 3 LSZP 1 3 T 3 as v i y r T y r , . v y ' "TyTT v y ' TyT~ TyT So o .g diagenesis "K 8 carb SS description a/ </ c/ c/ c/ / / c/ c/ 185 we!l#: 16-7-6-2W2 cored interval (metres): 1210.6-1228.9 Q> -'o g- o "§ •§ diagenesis "a 8 carb SS description well #: 6-16-6-1W2 cored interval (metres): 1169.2-1181.4 C L CD 45 O £ B Z3 O o -S diagenesis 8 carb SS description 1170 -2 7 zzz well #: 8-1-6-2W2 cored interval (feet): 3953-3994 CL CU T3 CU O CO O 9> CO o & diagenesis ts 8 carb SS description 3975 —t 3990 -ZvE E r Z9I nszE TC I ic_r rcr ZCJ: rcj En 3-Cr lower contact; load and flame structure some quartz sand 188 weli#: 11-1-6-3W2 cored interval (metres): 1222.5-1240.8 to cu oo CD OO g - o " -§ diagenesis to o carb SS description 1225 -1230 —6 1235 -1240—f. n n n n 30 cm thick dolomudstone interval with sharp contacts well #: 16-15-16-3W2 cored interval (metres): 1213.7-1232 C L CU •o o "§ -S diagenesis 8 carb SS description 190 well #: 3-2-6-3W2 cored interval (metres): 1232-1249.4 CL cu X J cu o o CO P C O •S diagenesis 8 carb SS description 1235 -1240 • 1245-13 V v vi ' V 7 r v v vi v v v ' v v 1 v v v f..v,. V7 .-q G S I sub-Mesozoic unconformity upper contact; gradational into thin dolomudstone lower contact; thin 10 cm dolomudstone between lithofacies 191 well #: 8-1-6-3W2 cored interval (metres): 1221.5-1240.5 to cu to £ co i3 o g - o y -§ diagenesis 7 3 = -io 8 carb SS description 3 y y Sri n s ,. • . , G G quartz sand present 192 well #: 8-24-6-3W2 cored interval (metres): 1209-1219 •8 92 J2 g- o s diagenesis carb SS description V V V V V V V V V ' V V V sun-Mesozoic unconformity well cemented 20 cm dolomudstone lower contact; load and flame structure quartz sand present 193 well #: 2-25-6-4W2 cored interval (metres): 1246.8-1264.8 "g & diagenesis "Lo 8 carb SS description sub-Mesozoic unconformity lower contact; load and flame structure quartz sand present 194 well #: 4-33-6-4W2 cored interval (metres): 1254-1272 CO CO C L cu •S 2? l i l = CO o 1255 1260 -I 17 $ *7 V V V f v v v| V V V ' V V vi V V V 1265-1270-~7Z~Z zzz Z Z Z ^ ST n n n n G n diagenesis carb SS description laminated and mottled 195 well #: 7-29-6-4W2 cored interval (metres): 1281-1263 well #: 11-25-7-4W2 cored interval (metres): 1210.9-12277 •a g* g- o "§ -2 diagenesis = -ts 8 carb SS description 3JL IHE 1 3 1 Q | 0 THI Q j O H I H I H E r n L H IHE 0 | o H E o I o H E 0 1 0 H E 0 j o H H 3H H H H E Q j O 0 j 0 0 | O H E 0 I o in E H 0 I Q 3 H I 0 I 0 H E 0 I 0 0 1 0 H H H E red stain 197 well #: 1-27-7-4W2 cored interval (metres): 1202-1220 •S £ sa 3 3 y o " 3 diagenesis = « 8 carb SS description l I ° I 1205 -V7/\ 7Z7Z\ 1210-1215 —F 1220-198 well #: 13-20-7-4W2 cored interval (metres): 1226.8-1245.1 CU CD "o J5 o fD tn •g ss diagenesis "Lo 8 carb SS description 1230 -1235 1240-1245-/ / / // / / yy / ' // / // / // / (// / / // / ' // / // / // / / yy / ' // / // / ' // / ' // / ' // / // / ' // / i i ° i — 0 o G | I I o | 0 0 © r I I o | — 0 J 0 I o I I I 0 I 0 | 0 0 r I I ° | — 0 I f I © i T I ° l , 0 I * I Q | I I 0 I — 0 o 0 | I I ° I 0 o © r I I 0 I — 0 0 o \ I I 0 I 0 CO 0 I I I 0 I — 0 0 0 I 0 I 0 I 0 I I I ° — 0 0 I I I 0 I 0 0 I G I I ° I . — 0 0 0 | 0 Je I © | " | 0 — 0 "j"o r © | , i ? 0 0 0 | I I 0 I — o 0 0 | I I o | o o 0 | I I e | 0 o O | 0 o O ] A ° J O I © I O | I 199 well #: 1-32-7-4W2 cored interval (metres): 1196.9-1233.5 CL CU XJ CD O o fD « ZD ti o .2 diagenesis •Jo 8 carb SS description 1200 -3 3 1205 -1210-T I 1215-G G sub-Mesozoic unconformity at 1206; gradational upwards to crinoid grainstone thin grainstone at base of interval; upwards accross Styolite contact transitions to a crinoid mudstone mottled at 1215; gradation from wackestone to crinoid grainstone continued on next page 200 well #: 1-32-7-4W2 cored interval (metres): 1196.9-1233.5 facies def lithol 1215 I ' T 0 I ' o 0 0 | I I 0 I — G 0 I I 0 0 0 0 I ! I 0 — 0 0 I I 0 0 0 © I I I o | — 0 0 Q | . . . 0 © 0 o r I I 0 I — o 0 0 | J L 0 J _ _ 0 0 0 | 1220 — J L0 J _ _ 0 0 0 [ 0 © 0 0 j i z m j . — 0 0 0 | I I 0 I o 0 0 | I I 0 I 0 0 O I I I G I 0 0 0 | I 1 0 1 0 0 0 |. I I ° I 0 0 0 | A _ L 0 J _ _ — 0 0 0 I I t 0 I 0 0 0 | . _ J 0 _ 1225 — O 0 1 0 I I I ° J L 0 o | TJ I I ° I 0 0 © | _L L°J_ ._ 0 0 0 | I I 0 I O 0 © r I I 0 0 0 | 0 | J I 0 _ 0 0 0 | I I 0 I 0 0 0 I I I 0 I — 0 0 0 i I I 0 I 0 0 0 | I I 0 I 1230 — 0 0 0 | I I 0 I 0 0 0 I J 0 J . 0 0 O I I I 0 I 0 0 0 |_ I I 0 I 0 0 0 I . L . J _ ° _ 0 0 0 | I I 0 I 0 o © I I I 0 I rs I I m l £ LO O "g & diagenesis "io 8 carb SS description above 1228; crinoid lithofacies consist of mudstone and wackestone below 1228; crinoid lithofacies consist of interbedded grainstone and mudstone. 201 well #: 14-18-74W2 cored interval (metres): 1222.2-1240.2 CL CU T3 CU O CO O JC £ su =J o o 3 diagenesis -i? 8 carb SS description 1225 — 1230 -1235 -1240—f 3 r V V V ' v v M v v v ' v v M 7-31 3 n 3 3 3=3 1 3 31 3 n ST <7 sortie carbonate clast mottled 202 well #: 15-24-7-4W2 cored interval (metres): 1202-1220 •S £ & £ CD Z3 O g- t5 " -| diagenesis 7 3 = -io 8 carb SS description ! I 0 I 0 © 0 ] I I 0 0 © 0 j I ! » 0 0 0 J I 0 I 0 . © 0 | I 1 0 ! 0 0 0 1 1 1 0 I 0 0 | 1 1 0 1 0 0 [ 0 0 | 0 © | 1 ® 1 0 0 | 1 0 1 0 0 | 1 1 ° | 0 © r 1 1 ° 1 0 0 1 o 0 | . . . 0 0 0 1 0 0 0 1 . 0 0 0 1 1 0 1 o 0 | _ J 0J._... 0 0 | _L. I 0 L. 0 0 | 0 0 j 1 0 1 0 0 [ 0 0 | 1 1 0 1 0 0 j J 1 '1 0 0 | © 0 1 i « i © 0 | 0 0 1 0 o O J 0 0 0 | | 0 | 0 © I 1 0 1 0 0 \ 0 1 © 0 | n 0 o 0 J ____L® .. 0 0 J JLJ 0 0 thin; gray dolomudstone at top of core 203 well #: 2-10-7-4W2 cored interval (metres): 1230-1262.5 C L CD "Ct 45 o £ B "g 3 diagenesis "Lo 8 carb SS description 1230 -r v v v| v v v 1235 —[ 1240 -1245 -Z Z E T EZE I I - I EZE r z n n ST G Z Z E rz zzzz zzzz 3 / / / H Z ZZE 0 | O TZZ Z Z 0 | 0 0 | CO zz continued on next page 204 well #: 2-10-7-4W2 cored interval (metres): 1230-1262.5 CD o CO a? B zz o g -2 diagenesis •i? 8 carb SS description _L' I A.L' o © \ © | I I ° I o o © | t I ° I 0 o © 1 10.1 0 0 © | J I ° .. 0 0 0 J_ I I o | 0 0 0 | i i <^r 0 0 0 | I P I 0 0 © 1 i r °n 0 0 G | 1250 — I L T 0 0 © 1 _L ... ° .... O 0 O | ___ P . O 0 © | I I ° I 0 0 0 I I P I 0 0 © | I P | o 0 Q | I P I 0 G 0 | I P I o 0 © | J . . ° . . . — 0 0 0 | _L__.L° L. G 0 0 . I P I 1255 — G 0 0 1 _L__1A.L_. © 0 0 | _L_. ® — © 0 0 1 J 0 L . © 0 0 | I P I —• 0 0 0 | i i °n 0 0 0 ! I P I — G 0 0 1 I P I Q 0 0 | 1... P L — 0 o I 0 1 1 P I 0 0 © | P 1260 — 0 G © | P 0 G © |_ 0 © | © 1 _L_ L ° J _ . 0 Q j _L P 0 0 0 _ | 1 p | « « « _L 205 well #: 2-14-7-4W2 cored interval (metres): 1230.1-1245.7 to CD to £D CO g - o "§ •§ diagenesis 8 carb SS description 1230 — 1235 1240 -1245- NO 206 well #: 3-24-7-4W2 cored interval (metres): 1208-1226.1 .to <-> to °- o "g -2 diagenesis to 8 carb SS description 1210 1215 -1220 -1225Z-TJ7 ra ra I X nit H i HE HE 3n H i I B Z 3 ra 3 1 207J well #: 9-6-7-4W2 cored interval (metres): 1258-1276 7\\ v t diagenesis = 5 8 carb SS description 1260 —R G G 1265 • H ST 1270—G n ST 1275- I 40 cm interval; facies has a brecciated texture two thin (4-6 cm) Kisbey sandstone intervals with sharp contacts some quartz sand mottled textured and red stain -208J well #: 10-29-7-5W2 cored interval (metres): 1221.5-1239.5 CL CU CU O 45 o 2> to =J tS o 45 diagenesis tz 8 carb SS description 1225 -1230 -1235-' V V vi V V V ' V v vi G G G G S G G G I 15 cm thick anhydrite interval at contact minor amounts of quartz sand red stain; mottled 209 well #: 11-28-7-5W2 cored interval (metres): 1213.5-1231.5 CD X J 1215-J 1220 . 1225-1230-CO cu CO "g ss diagenesis 8 carb SS ' V V M V V V ' V V v| V V V ' V V vi V V V ' V V V] y-7 w a . - I - I - I IEST NO G n s I description 210 well #: 1-24-7-5W2 cored interval (metres): 1221.8-1240.2 CL CD T3 CD O •2 o P C O o -2 diagenesis •K 8 carb SS description 1225 1230 -1235-1240-n ST some quartz sand 211 well #:16-12-7-5W2 cored interval (metres): 1245-1263 C L CD "O CD O >2 O fD (O =) "o "g -2 diagenesis ^ -K 8 carb SS rrzr E X description E E E E I . I -1 I - I - I I - I - I I I - I E E E E T Z l E E Z Z I - I - I I I I I - I - I T E E TZ3 H ST n ST I abundant anhydrite interval is mottled 212 well #: 8-30-7-5W2 cored interval (metres): 1230.4-1248.5 Q. CU CD O co o CO fD to o -S diagenesis •is 8 carb SS description 1235-1240 • z z zz F E -I I —I zzz 11 1245 H G G n ST E abundant quartz sand 213 well #: 9-21-7-5W2 cored interval (metres): 1223.7-1242 "g & diagenesis 8 carb SS description from 1229 upwards core is a lime mudstone with some peloidal intervals 214 well #: 16-34-7-6W2 cored interval (metres): 1243.8-1305.4 C L CD •o 1285-'o 4° o £ <2 Z3 O "§ -2 diagenesis is 8 carb SS description 1290 . ' V V vi V V v ' V V vi V V V ' V V v i V V V ' V V Vi V V V ' V V v i V V V ' V V vi V V V ' V V Vi V V V ' V V v i V V v 1295 1300-1305-V7 5 V V V NO NO NO NO NO NO <2> red stain 215 well #: 11-11-8-4W2 cored interval (metres): 1182.6-1210 C L O J " O OJ o 45 o JJ CO Z3 " O o is diagenesis -is 8 carb SS description 1185 -4 1190-Q | n m F T G S I sub-Mesozbic unconformity mudstone load and flame structure at lower contact; mottled; some crinoid grains in sand near upper contact continued on next page 216 well #: 11-11-8-4W2 cored interval (metres): 1182.6-1210 CO OJ o CL OJ T3 CO — o "g js diagenesis -K 8 carb SS ' / / / ' / / / / / / / — o © | 0 [ J ° J _ O © | 0 | — 0 0 | Q | 0 © ! O I — 0 © I 0 I I I ° I 0 o j © L J L°J — 0 0 | _L L° J 0 0 | I I o I — O © [ I ° I 0 © | i r ° i — o 0 j 0 0 | I I ° I — 0 © i © 0 I I I • I — O © I _ J °J _ 0 © I | o | 0 0 | I I 0 I o © [ j I © I — 0 0 | I I ° i 0 O | i r° i — © 0 | _L_. ° 0 0 | I I G I — o Q | I I o | G 0 j _L L°J . — . © 0 | I I c I 0 © L I I ® I. — 0 0 l I I » I 0 0 | I I o | Q 0 ] I I « I 0 0 I I I ° I 0 © I | | © | 0 0 j r i ° i © 0 I I I o.| 0 0 \ O 0 | I I ° I 0 © I I o I 0 © I | 0 © 0 | I I ° I „ I „ I - I description mottled, red stain grainstone at base; mudstone from 1209.7 to 1208.7; gradational up to grainstone; grainstone up to 1208.2; gradational up fo mudstone; thin mudstone up to 1208; gradational up to grainstone; grainstone up to 1197.8; stylolite contact up to mudstone; mudstone up to 1195.4; gradational up to grainstone; grainstone up to 1194.8; gradational up to mudstone; mudstone up to 1194.4; grainstone up to 1193.4; gradational up to mudstone; oil stained from 1192.5 upwards 217 well #: 11-12-8-4W2 cored interval (metres): 1179.5-1210 C L CD X ) CD O »2 O to £ <2 = J o g -2 diagenesis ts 8 carb SS description 1180 1185-1190-O | G | Q TJEL 0 | 0 E3L J2U Q | 0 _ O | Q 0 | O Q | 0 | T NO NO sub-Mesozoic unconformity grainstone at bast up to 1187.8; gradational contact up to mudstone; mudstone to top of interval mottled continued on next page 218 well #: 11-12-8-4W2 cored interval (metres): 1179.5-1210 cu T3 1190-cu ' C J 45 — 1195-1200 1205-1210-I I ° I ° I ° I ? I I I ° I nn I I ° Ie e' J™o"'J 0 I 0 | ~o~ i i ° i i i ° i DDI DDI D O DDI 13 D O 5 HI 3 3 £ <2 =3 O c| 45 diagenesis carb SS description grainstone at base up to 1207.8; sharp contact up to mudstone; mudstone up to 1202.8; sharp contact up to grainstone; grains! fines upwards to mudstone, contact not observed ; grainstone up to 1199.6; 219 well #: 1-13-8-4W2 cored interval (metres): 1188.7-1219.2 .92 o co £ jg .3 a .. g- o o -2 diagenesis ~° = § 8 carb SS description — o I o 1 0 1 I I ° I 0 | 0 1 Q 1 I 0 I — 0 | 0 1 0 I I ° I O I 0 1 0 1 I I ° I — 0 | 0 1 0 1 0 I 0 1 I J © 1 0 1 1195 — I I 0 I 0 U 1 1 © 1 I I ° I 0 0 1 © - 1 I I ° I — 0 | 0 1 ° 1 J _ . I I ° J © | 0 1 ° 1 r © — 0 I © 1 ° ! i i ° i 0 I 0 1 ° ! I _ . . . L ® . . . — 0 | © 1 © i I I ° I 0 | © 1 © 1 A 1 ° 1 — 0 | 0 1 © 1 1 1 o 1 © r © © 1 1 * | 1205 — 0 | o i © 1 1 1 ° 1 0 | © 1 ©_l_ J . . _ . . e . l — O I 0 1 © L | 0 | 0 | 0 1 © 1 ° — 0 | O 1 © 1 1 1 ° 1 0 | 0 1 © 1 1 1 « 1 — i 0 I 0 1 © 1 j 1 G I 0 | 0 1 © — 0 | 0 J 0 J_ J 1 ° _ L _ 0 1 0 1 0 i 1 1 ° 1 1215 — G 1 © 1 © 1 1 1 e 1 Q I © 1 0 1 A _ L ° _ L 0 G 1 © 1 1 1 9 1 0 0 1 © 1 I 1 0 G | 0 1 © [ grainstone interval from 1216.5-1217.5; fenestrate bryazoan at 1195; porous from 1207-1192 well #:13-12-84W2 cored interval (metres): 1184.1-1202.4 C L CD "CJ 1185-o fl> co => "o "§ B diagenesis J= o CO o carb SS description 1190-I I ° I 0 0 0 — 0 0 0 I 0 I 0 o 0 I I o | — 0 0 0 I I ° I G 0 0 I I ° I 0 0 0 J l_°_L O 0 0 0 0 O J _ . J ®\ 0 0 O 0 0 i i ° i o 0 0 i i ® i — o 0 0 i 0 i 0 0 0 1 ° 1 — 0 0 0 i i 0 r G 0 G I 1 ® 1 o 1 ® 1 0 ( / / / / 1195-1200" I , I ? I ~2L rzzzz, 3 zz 3 z z 2 3 X o | o 0 o Tp: O 0 xp: 0 | 0 JJfL © o JJfL 0 © X Z L n G S base of interval is a grainstone; grades up to wackestone; stylolite contact at 1190.8; grainstone to top of core; patchy oil stain sandy dolomudstone; base of interval is red stain and mottled; oil stained from 1196.3 up to 1192 base is a wackestone; upwards change to dolomitimized mudstone; grainstone at 1199.5 with red stain 221 well #:13-1-8-4W2 cored interval (metres): 1182-1200.6 cu oo .CO g- o y -§ diagenesis 8 carb SS description 13 53 33 13 3 3 3 3 3 3 0 I O I 0~E"T E E E E T E 331 E E 133 n m E H 3 3 H I o I o f 333T 0 [_ 0 | E T O | 0 JJJZ 133 E E T 3 3 E m E r E 3 33 E E ffi I m I NO NO I I mudstone; syringopora at top of interval oil stain; faint mottled texture near top grainstone from 1195 to 1194.2; mudstone above to top of interval; patchy oil stain oilstained; loose oil stain near top grainstone at base; mudstone from 1200.2 to 1199.1; stylolite contact upwards to grainstone; gradual increase in quartz content and mud upwards 222 well #:15-12-8-4W2 cored interval (metres): 1171.9-1208.5 CD O Q-CD fD OO Z3 tS o js diagenesis "io 8 carb SS description 1175-1180-1185 — 1190 -0 I a | s T 1 I 8 B I. a I ° T I I ? I ° I ° I a I sub-Mesozoic unconformity base is a mudstone; gradational upwards to wackestone; dolomitized base is well cemented and mottled; oil stained from 1192.5 to top of interval; at 1193 loose mottled texture upwards; at 1191 a 7 cm thick well cemented zone at 1190.3 motteled texture upwards; upper contact gradational over 1 metre continued on next page 223 well #:15-12-8-4W2 cored interval (metres): 1171.9-1208.5 CL CU TJ cu "o o 3 53 33 33 33 T°T 3 1 3 1 E33 133 3 1 E?3 E 3 3753 3 3 3 TJTT 3 0 I 3 ^ 9> to "g ss diagenesis "to 8 carb SS description n mudstone at base up to 1208; contact, load and flame structure and infilled burrows; 40 cm of grainstone above; stylolite contact upwards to wackestone; wackestone up to 1205.4 stylolite contact up to grainstone; grainstone from 1205.4 to 1204.6; stylolite contact up to wackestone; wackestone up to 1201; stylolite contact up to grainstone; grainstone up to 1198.4; gradational contact up to mudstone and wackestone; wackestone and mudstone up to top of interval 224 well #: 15-1-8-4W2 cored interval (metres): 1197.8-1207 CL TD CD O £ J2 ZD O o & diagenesis "io 8 carb SS description 1200-1205 n n n 40 cm grainstone at base; oil stain; stylolite contact; mudstone up to 1204.2; stylolite contact; loose oil stain at 1200.5; some oolites in grainstone at 1999; quartz rich crinoidal grainstone at 1198.6 with 2 cm thick sandstone caps zone; grades up to mudstone 225 well #:16-12-8-4W2 cored interval (metres): 1190-1204 C L CD "0 CO CD " O CO O CO £D CO o ss diagenesis 8 carb SS description 1190-1195 — 1200 -grainstone from 1204 to 1200; sharp contact up to mudstone; mudstone from 1200 to 1198; gradational change to grainstone; grainstone from 1198 to 1196.8; mudstone from 1196.8 to 1193.4; gradational change to grainstone; grainstone to top of interval 226 well #: 2-13-8-4W2 cored interval (metres): 1186-1200 P LO CL CD "a 45 o diagenesis carb SS description r r z z : 1190 • 1195 -1200-2 2 Z Z T 7 rz" n n quartz grams near lower contact, crinoid lithitacies at top ot core across a stylolite red satin and mottled at lower contact; possible load and tlame structure; well cemented at base; at 1195.5 becomes oil stained upwards; 15 cm thick dolomudstone at 1195; at 1194.6 muddy zone with fenestrate bryazoan; possible burrow at 1191.3 red stain; mottled; fenestrate bryazoan present; silt sized quartz grains present near upper contact 227 well #: 3-12-8-4W2 cored interval (metres): 1186.5-1218.8 C L CD XJ 00 CD O JS o 00 CD CO z i "£> "g .2 diagenesis "to 8 carb SS description 1190 • 1195-1200-z z TZZC Tp o © ZZE Z~T G O ZL7ZC O | G zz: G a x°z G | O zb: G Q zz: O I 0 " H p -a | G I 228 well #: 3-12-8-4W2 cored interval (metres): 1186.5-1218.8 CO .92 CO cu <o o lithofac i ZD dap r lithofac struct conta 1200—^ SS 1205 -1210 -1215-o I o I a T I I ° I I B I | _ 0 _ :r°n EZT o | 1 ©""ji i ; i ? i 0 0 O rrifr 0 0 0 1 i ° I 0 0 0 o o © rrffr o o © 1 i»i 0 0 0 1 I * I o © © I ° I a I e I o I I I f I © 0 © I ? I 0 0 0 1 I ? I s e e I I ° I 0 o © 1 I ? I 0 I © j © 1 i - i 0 0 O 1 I ? I 0 O 0 I I I Q | 0 J ' _ Q _ | 1 J f I 0 0 © I I I Q | Q | Q 1 I Q I © © 0 I I e I G G NO I description above 1202.4 sand grains are coated with bitumen mottled; fenestrate bryazoan thin dolomudstone at base; gradational upwards to sandstone; oil stained 20cm grainstone at base; mudstone from 1218.8 to 1216.4 with a 15 cm grainstone interval; gradational contact to grainstone; grainstone up to 1214.2; gradational contact up to mudstone; mudstone up to 1207; stylolite contact up to grainstone; grainstone up to 1205 229 well #: 3-13-8-4W2 cored interval (metres): 1185.3-1193.6 CL CD T3 •8 s> & ro 3 " o "§ -§ diagenesis = to 8 carb SS description 1190-I I ? I o I 0 I B F 0 I 0 I °7 I I ? I I 0 I 0 I 0 I 0 T crinoid mudstone; dolomitimized; 6 cm thick pisoid interval at 1186.8; brachiopods and coral fragments oil stain near top 230 well #: 4-13-8-4W2 cored interval (metres): 1196-1214 •8 s <2 £ CD 3 U g- o g -§ diagenesis 7 = 1 = S 8 carb SS description 1200 -1205 -1210-Q | O J e Q | O JEEE TJCL J E T in j o J T HE Hr Hr I E Hr Hr Hr J T Hr J T Hr J T Hr H E n ST n ST n ST 231 well #: 5-13-8-4W2 cored interval (metres): 1185.6-1194.8 C L CD UJ CD "o 45 o £D WJ "g -S diagenesis £= O uj o carb SS description o I o znpz o o T°T-O Q Wackestone interval dolomitized from base up to 1189.6; crinoid molds filled with anhydrite; oil stained mudstone; gradatiol contact to grainstone at 1186 well #: 6-12-8-4W2 cored interval (metres): 1188.7-1207 co CL CU T3 CO £ is o "_> -| diagenesis = -&5 8 carb SS description 1190 -1195. 1200 1205-• - • -• - • — • - • • -- - - - -— - - - - -. _ . . _ - - • -— - • - -- - - -- - - -I I 0 I 0 0 0 _ L I. 0....l — © 0 0 0 0 o I I 0 I — 0 0 0 0 0 0 I I o | © 0 0 I I O I 0 o 0 A l_° I 0 0 0 I I ° I 0 0 r© O i « i 0 1 I I ° | / ' / / / // / v // / //. / / ' // / / // / ' // / ^ // / ' // / y/ / // / / y / ' // / ' // / ' // / ' / / / ! ' I 0 ! ' — I 0 © | 1 0 i 0 1 0 ] 1 1 0 I — O 0 0 0 © 0 © 1 1 0 1 — 0 0 0 0 0 0 0 1 1 0 1 . i _ i _ i S -sub-Mesozoic unconformity Thin sandstone and crinoid grainstone at basal contact red stain; mottled; upper contact may be infilled burrow or load and flame structure 233 well #: 7-12-8-4W2 cored interval (metres): 1190-1216.7 .32 CD co £ CD 3 o g- o "§ -| diagenesis 7 3 = -to 8 carb SS description 1195-0 I 0 I e e I s ! 0 | e | 0 | 0 1 ° I , I I ° I I ? I 1200-sub-Mesozoic unconformity mudstone at base of interval up to 1197.4; stylolite contact up to grainstone grainstone up to top of interval continued on next page 234 well #: 7-12-8-4W2 cored interval (metres): 1190.8-1216.7 CO OD Q . 45 CD ° -a £ J T T £ <2 Z J o "g i j diagenesis to 8 carb SS G i s EHO xz nrn 3 I 0 E H I | a [ I? I ° I ? II Z H I 3 HHP G | 0 I 0 I I I I 0 0 0 1 1.°1 0 0 © 1 I ? I 0 0 0 , l I I see 1 I ° I 0 | H I HD I I ° I description gradational up to crinoidal mudstone at 1201.8 crinoid molds in sandstone near contact sandstone is a muddy sandstone with green lamina mudstone from 1216.7 to 1214.6; sharp contact upwards to grainstone; oil stained; grainstone up to 1213.6; gradational up to wackestone; wackestone up to 1208.5 235 well#: 13-7-8-5W2 cored interval (metres): 1228-1246 CD go £> co Z3 "tS o s diagenesis •s 8 carb SS description I I 1230 • I l l I • I » I I I-I » I » I I I ; I I • I « I I I ' I I I I I , I ' I I • I ' I I • I : I • I I ; I 1235 -zzzz 7 Z E 1240-1245-G G S G red stain; broken tabular lamina laminated pisoids, 20 degrees of dip thin sandstone at 1235.2; lower contact, load and flame structure oil stained upwards from 1237.6; lamina dips 10-30 degrees well cemented; red stain; mottled; abunadant skeletal fragmentsat 1240.1 crinoids and brachiopods 236J well #:15-6-8-5W2 cored interval (metres): 1199-1218.5 CU X J OO CU "o 45 o oo cu <n "g 4| diagenesis "o  8 carb SS 1200_ 1205. 1210-1215-// V 7 7 3 ? T 7 Z 7 rz zz zzz 7 Z 7 7 Z 7 ZZZZ Z 7 Z X i Z i ° i S f\ ST G G n ST I description ooid skeletal grainstone ooid skeletal grainstone 237 well #: 4-7-8-5W2 cored interval (metres): 1189.5-1207.5 x: lithofacies ures dep lithofacies struct conta 1190 — ^ I ICI ZEE l l' l n ST G G diagenesis carb SS description 238 well #: 5-7-8-5W2 cored interval (metres): 1185-1203 CL CU T3 CU O 45 o s? & Z3 O o -S diagenesis i l 8 carb SS description 1190-r~77~ 1195-1200 H ' I . I ° I i » i « i XTJ I I * I l l • l 3TTJ Z Z 3 E Z E I - I » I I I ° I I I I I ; I ZZ G G G I 2 3 9 well #: 7-7-8-5W2 cored interval (metres): 1191-1209 C L CD •o CD O >2 O £ <2 => o g & diagenesis "io 8 carb SS description 1195-i/. /:/. :/J n ST 1200 • 1205-silt sized quartz grains laminated pisoid ooid skeletal grainstone, lamina dip 10 degrees 240 well #: 10-13-8-6W2 cored interval (metres): 1183-1201 •S 2 JS £ CD =3 O CD o § -§ diagenesis ^ i S 8 carb SS description I I I zz 1185- rv-' v v M y.v.v i n I I I i ' i i i i « i 1190 -1195-1200-Z2 S S G G I 3 cm thick anhydrite interval with quartz sand green wispy lamina quartz sand is abundant 241J well #: 13-12-8-6W2 cored interval (metres): 1191-1201 CX CU T3 CO CU O 45 o CO P CO o -S diagenesis •is 8 carb SS description 1195-1200 ZZ oolitic grainstone top 30cm of interval -242J well #: 4-13-8-6W2 cored interval (metres): 1187-1205 CO — CD co f— CJ >— Jl3 g- o y -2 diagenesis 7 = 1 = "K 8 carb SS description 1190-3 Z O I E E 3X_ 3 EX3 r n 3 7 r n I I • i rz i . i - i 1195 - I • I »I Z Z Z Z Z rz 1200-1205-G G G G some vein anhydrite near top of core minor amount of quatrz sand; broken tabular lamina 243 well #: 4-23-8-6W2 cored interval (metres): 1200.6-1216.1 CL OJ •o 45 o £ & =3 O •g & diagenesis to 8 carb SS description 1200-1205 -1210-1215—To I I <? I I T L DA DDI DC I T D D T I T D A D O n J T D A D A Z A I D 3 D r j n : 0 I ? J E A D A E D ? I ? 3 D ? I f o _ I e "Jl-?.. .1 ',1,' o ]" ©" 1DD crinoidal grainstone 244 well #: 7-15-8-6W2 cored interval (metres): 1195-1208 CL CD •2 O £ <2 3 O o 3 diagenesis "K 8 carb SS description 1195-1200 1205 " F T HE n n ST NO / / / / / / lime mudstone with red stain well cemeted sandstone; interbedded lime mudstone mottled, red stain 245 well #: 1-14-6-3W2 cored interval (metres): 1211.5-1229.8 •S 2 & g- O O a diagenesis 7 3 = to 8 carb SS description I I I 1215-1 3 3 133 3 3 3 3 3 3 3 TZ. 3 3 333 333 3 3 3 133 3 1 3 3 133 ~T~-~T 1220-3 3 3 3 3 3 3 3 1225-3 3 3 3 3 3 / / ./, 3~n^" 3 3 S G S G G I I some vein anhydrite 246 well #: 12-34-5-3W2 cored interval (metres): 1240.5-1258.8 CD 1240 -CO S; £ m 0 o -2 diagenesis 1 i l 8 carb SS description 1245-1250 • zn S3 1255 -7 7 7 V T Z 7 7 7 7 7 7 G G I G G sub-Mesozoic unconformity coated grain; gradational to coated grain over approximately 2 metres scattered anhydrite noduals throughout interval single ortenella grain some grainy(peloids) intervals brecciated texture at base red stain with some sandy intervals gradational change upwards to dolomudstone interval has abundant anhydrite noduals and carbonate mud; anhydrite obscures original rock type thin (10 cm) dolomudstone interval; sharp lower and gradational upper contact horizontal lamina at base; upwards lamina dips 15 degrees anhydrite noduals present 247 well #: 3-2-6-33W1 cored interval (metres): 1115.5-1179 CL CU T 3 2 o to £ J2 — to 8 diagenesis carb SS description 7 Z 7 zzz Z Z Z Z zzzz zzzzz Z Z Z Z Z L ZZJ zu zzz zz o | o ZZZ r z 0 | 0 ZZJ zz 0 | Q_ x z x z O | 0 XZ 0 | G r z O | 0 TZ2Z 0 | 0 0 | 0 TZZ XZ rzr r z Z i x z zz x z x i x i x i continued on next page 248 well #: 3-2-6-33W1 cored interval (metres): 1115.5-1179 cu CO cu o 45 o CO CD co Z3 tS o ij diagenesis -fc= o CO o zzs zr_z zzz/. zz, /, zz zz carb SS description coated grainstone MC-2 marker ooid grainstone continued on next page 249 well #: 3-2-6-33W1 cored interval (metres): 1115.5-1179 C L CU 1160-"o o o ij diagenesis "io 8 carb SS description 1165-1170 • 1175-250 

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