{"Affiliation":[{"label":"Affiliation","value":"Science, Faculty of","attrs":{"lang":"en","ns":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","classmap":"vivo:EducationalProcess","property":"vivo:departmentOrSchool"},"iri":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","explain":"VIVO-ISF Ontology V1.6 Property; The department or school name within institution; Not intended to be an institution name."},{"label":"Affiliation","value":"Earth, Ocean and Atmospheric Sciences, Department of","attrs":{"lang":"en","ns":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","classmap":"vivo:EducationalProcess","property":"vivo:departmentOrSchool"},"iri":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","explain":"VIVO-ISF Ontology V1.6 Property; The department or school name within institution; Not intended to be an institution name."}],"AggregatedSourceRepository":[{"label":"AggregatedSourceRepository","value":"DSpace","attrs":{"lang":"en","ns":"http:\/\/www.europeana.eu\/schemas\/edm\/dataProvider","classmap":"ore:Aggregation","property":"edm:dataProvider"},"iri":"http:\/\/www.europeana.eu\/schemas\/edm\/dataProvider","explain":"A Europeana Data Model Property; The name or identifier of the organization who contributes data indirectly to an aggregation service (e.g. Europeana)"}],"Campus":[{"label":"Campus","value":"UBCV","attrs":{"lang":"en","ns":"https:\/\/open.library.ubc.ca\/terms#degreeCampus","classmap":"oc:ThesisDescription","property":"oc:degreeCampus"},"iri":"https:\/\/open.library.ubc.ca\/terms#degreeCampus","explain":"UBC Open Collections Metadata Components; Local Field; Identifies the name of the campus from which the graduate completed their degree."}],"Creator":[{"label":"Creator","value":"Harris, Richard Gordon","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/creator","classmap":"dpla:SourceResource","property":"dcterms:creator"},"iri":"http:\/\/purl.org\/dc\/terms\/creator","explain":"A Dublin Core Terms Property; An entity primarily responsible for making the resource.; Examples of a Contributor include a person, an organization, or a service."}],"DateAvailable":[{"label":"DateAvailable","value":"2009-07-06T22:42:08Z","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/issued","classmap":"edm:WebResource","property":"dcterms:issued"},"iri":"http:\/\/purl.org\/dc\/terms\/issued","explain":"A Dublin Core Terms Property; Date of formal issuance (e.g., publication) of the resource."}],"DateIssued":[{"label":"DateIssued","value":"2000","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/issued","classmap":"oc:SourceResource","property":"dcterms:issued"},"iri":"http:\/\/purl.org\/dc\/terms\/issued","explain":"A Dublin Core Terms Property; Date of formal issuance (e.g., publication) of the resource."}],"Degree":[{"label":"Degree","value":"Master of Science - MSc","attrs":{"lang":"en","ns":"http:\/\/vivoweb.org\/ontology\/core#relatedDegree","classmap":"vivo:ThesisDegree","property":"vivo:relatedDegree"},"iri":"http:\/\/vivoweb.org\/ontology\/core#relatedDegree","explain":"VIVO-ISF Ontology V1.6 Property; The thesis degree; Extended Property specified by UBC, as per https:\/\/wiki.duraspace.org\/display\/VIVO\/Ontology+Editor%27s+Guide"}],"DegreeGrantor":[{"label":"DegreeGrantor","value":"University of British Columbia","attrs":{"lang":"en","ns":"https:\/\/open.library.ubc.ca\/terms#degreeGrantor","classmap":"oc:ThesisDescription","property":"oc:degreeGrantor"},"iri":"https:\/\/open.library.ubc.ca\/terms#degreeGrantor","explain":"UBC Open Collections Metadata Components; Local Field; Indicates the institution where thesis was granted."}],"Description":[{"label":"Description","value":"Middle Triassic Doig reservoirs in the Fireweed, Buick Creek, Cache Creek and West\r\nStoddart fields (94-A-13 to Twp.86, Rge.18) of northeastern British Columbia consist of\r\ndeltaic and shoreline sands encased in shelf and offshore mudstones and siltstones.\r\nThe reservoirs comprise a series of northwest and northeast trending elongate sand\r\nbodies that lie along a south-southeast depositional trend analogous to the position of\r\nthe original Doig shoreline.\r\nSediments of the Doig Formation are divisible into two facies associations and ten\r\nlithofacies representing deposition in shelf to offshore, and deltaic and inter-deltaic\r\nenvironments. Hydrocarbon producing intervals consist of clean, very fine to fine\r\ngrained, sub-lithic to quartz arenites, inter-bedded sandstones and bioclastic detritus,\r\nand disseminated bioclasts. Effective porosity is primarily inter-granular in the\r\nsandstone facies with significant moldic and intra-granular porosity developed in the\r\ncoquina facies at the West Stoddart and Cache Creek fields. Average porosities range\r\nfrom 6.5 - 9.5% for sandstone lithofacies and 4.9 - 8.6% for coquina lithofacies. Pore\r\noccluding cements are mainly calcite in the northwest part of the reservoir trend to\r\ndolomite and anhydrite in the southeast. The sedimentology and facies architecture of\r\nrecent discoveries at Cache Creek and West Stoddart contrast with those identified in\r\nprevious studies of Doig reservoirs at Buick Creek in northeastern British Columbia and\r\nSinclair in west central Alberta.\r\nA three-dimensional facies model of the Doig Formation at the Cache Creek, West\r\nStoddart and Fireweed fields depicts sandstone deposition in a deltaic environment as\r\ndistributary channel fills and slumped delta front deposits. Data for the Buick Creek field confirms and extends the incised shoreface model to include fluvial or tidal channels\r\ndeposited laterally continuous in the same systems tract as the shoreface sands. Sand\r\nbodies for all four fields were deposited contemporaneously as the Doig shoreline\r\nprograded over mudstones and siltstones of the Doig shelf. Seismic and well data\r\nreveal tectonic control on the position and orientation of the Doig reservoir trend. Synsedimentary\r\ngrowth faults control the location and geometry of thick sand bodies along\r\nthe reservoir trend in the Fireweed area.\r\nDiagenetic controls along the reservoir trend include the precipitation of calcite in the\r\nnear surface and shallow burial realm, fracturing of cemented horizons prior to\r\nextensive burial and dissolution of cements and framework grains in three distinct\r\nepisodes. Multiple dissolution phases created moldic, vuggy and inter-granular\r\nsecondary porosity. Reservoir quality and production from Doig Formation sand bodies\r\nin the Peace River area of Western Canada are significantly impacted by the\r\npreservation of inter-granular porosity and fracturing related to the distribution of early\r\ncalcite cements. The early calcite cements were sourced from bioclastic debris and\r\ncalcareous mudstones distributed during sand body deposition. The formation of open\r\nfractures during early diagenesis enhanced both the secondary pore network and the\r\npermeability of the West Stoddart and Cache Creek Doig pools. Sand bodies with only\r\nminor interstitial calcite have extensive porosity loss by compaction and precipitation of\r\nauthigenic quartz.\r\nA fairway for Doig sand body exploration is constrained by production and core\r\nanalysis data, structural and depositional models, thermal maturity data and\r\ndiagenesis.","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/description","classmap":"dpla:SourceResource","property":"dcterms:description"},"iri":"http:\/\/purl.org\/dc\/terms\/description","explain":"A Dublin Core Terms Property; An account of the resource.; Description may include but is not limited to: an abstract, a table of contents, a graphical representation, or a free-text account of the resource."}],"DigitalResourceOriginalRecord":[{"label":"DigitalResourceOriginalRecord","value":"https:\/\/circle.library.ubc.ca\/rest\/handle\/2429\/10289?expand=metadata","attrs":{"lang":"en","ns":"http:\/\/www.europeana.eu\/schemas\/edm\/aggregatedCHO","classmap":"ore:Aggregation","property":"edm:aggregatedCHO"},"iri":"http:\/\/www.europeana.eu\/schemas\/edm\/aggregatedCHO","explain":"A Europeana Data Model Property; The identifier of the source object, e.g. the Mona Lisa itself. This could be a full linked open date URI or an internal identifier"}],"Extent":[{"label":"Extent","value":"8998073 bytes","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/extent","classmap":"dpla:SourceResource","property":"dcterms:extent"},"iri":"http:\/\/purl.org\/dc\/terms\/extent","explain":"A Dublin Core Terms Property; The size or duration of the resource."}],"FileFormat":[{"label":"FileFormat","value":"application\/pdf","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/elements\/1.1\/format","classmap":"edm:WebResource","property":"dc:format"},"iri":"http:\/\/purl.org\/dc\/elements\/1.1\/format","explain":"A Dublin Core Elements Property; The file format, physical medium, or dimensions of the resource.; Examples of dimensions include size and duration. Recommended best practice is to use a controlled vocabulary such as the list of Internet Media Types [MIME]."}],"FullText":[{"label":"FullText","value":"TRIASSIC DOIG FORMATION SAND BODIES IN THE PEACE RIVER AREA OF WESTERN CANADA : DEPOSITIONAL AND STRUCTURAL MODELS, AND THE IMPACT OF DIAGENESIS ON RESERVOIR PROPERTIES by RICHARD G O R D O N HARRIS B.Eng. (Hons.), Queen's University, 1990, 1997 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE D E G R E E OF MASTER OF SCIENCE in THE FACULTY OF G R A D U A T E STUDIES Department of Earth and Ocean Sciences We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA February 2000 '\u2022\u2022>;. \u00a9 Richard Gordon Harris, 2000 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia Vancouver, Canada DE-6 (2\/88) ABSTRACT Middle Triassic Doig reservoirs in the Fireweed, Buick Creek, Cache Creek and West Stoddart fields (94-A-13 to Twp.86, Rge.18) of northeastern British Columbia consist of deltaic and shoreline sands encased in shelf and offshore mudstones and siltstones. The reservoirs comprise a series of northwest and northeast trending elongate sand bodies that lie along a south-southeast depositional trend analogous to the position of the original Doig shoreline. Sediments of the Doig Formation are divisible into two facies associations and ten lithofacies representing deposition in shelf to offshore, and deltaic and inter-deltaic environments. Hydrocarbon producing intervals consist of clean, very fine to fine grained, sub-lithic to quartz arenites, inter-bedded sandstones and bioclastic detritus, and disseminated bioclasts. Effective porosity is primarily inter-granular in the sandstone facies with significant moldic and intra-granular porosity developed in the coquina facies at the West Stoddart and Cache Creek fields. Average porosities range from 6.5 - 9.5% for sandstone lithofacies and 4.9 - 8.6% for coquina lithofacies. Pore occluding cements are mainly calcite in the northwest part of the reservoir trend to dolomite and anhydrite in the southeast. The sedimentology and facies architecture of recent discoveries at Cache Creek and West Stoddart contrast with those identified in previous studies of Doig reservoirs at Buick Creek in northeastern British Columbia and Sinclair in west central Alberta. A three-dimensional facies model of the Doig Formation at the Cache Creek, West Stoddart and Fireweed fields depicts sandstone deposition in a deltaic environment as distributary channel fills and slumped delta front deposits. Data for the Buick Creek field ii confirms and extends the incised shoreface model to include fluvial or tidal channels deposited laterally continuous in the same systems tract as the shoreface sands. Sand bodies for all four fields were deposited contemporaneously as the Doig shoreline prograded over mudstones and siltstones of the Doig shelf. Seismic and well data reveal tectonic control on the position and orientation of the Doig reservoir trend. Syn-sedimentary growth faults control the location and geometry of thick sand bodies along the reservoir trend in the Fireweed area. Diagenetic controls along the reservoir trend include the precipitation of calcite in the near surface and shallow burial realm, fracturing of cemented horizons prior to extensive burial and dissolution of cements and framework grains in three distinct episodes. Multiple dissolution phases created moldic, vuggy and inter-granular secondary porosity. Reservoir quality and production from Doig Formation sand bodies in the Peace River area of Western Canada are significantly impacted by the preservation of inter-granular porosity and fracturing related to the distribution of early calcite cements. The early calcite cements were sourced from bioclastic debris and calcareous mudstones distributed during sand body deposition. The formation of open fractures during early diagenesis enhanced both the secondary pore network and the permeability of the West Stoddart and Cache Creek Doig pools. Sand bodies with only minor interstitial calcite have extensive porosity loss by compaction and precipitation of authigenic quartz. A fairway for Doig sand body exploration is constrained by production and core analysis data, structural and depositional models, thermal maturity data and diagenesis. iii TABLE OF CONTENTS Abstract ii Table of Contents iv List of Figures viii List of Tables x Acknowledgements xi C H A P T E R 1 - INTRODUCTION 1.1. - Introduction 1 1.4. - Structure of Thesis 2 1.5. - References Cited 3 C H A P T E R 2 - DEPOSITIONAL AND S T R U C T U R A L MODELS FOR DOIG FORMATION SAND BODIES IN THE P E A C E RIVER A R E A OF N O R T H E A S T E R N BRITISH COLUMBIA 2.1. - Abstract 4 2.2. - Introduction 5 2.3. - Geologic Setting 6 2.4. - Lithostratigraphy and Sand Body Geometry 10 2.4.1. - Facies and Facies Associations 12 2.4.2. - Cross-sections and Facies Architecture 14 2.4.2.1. - West Stoddart and Cache Creek 14 2.4.2.2. - Fireweed 16 2.4.2.3. - Buick Creek.... 19 iv 2.5. - Depositional Setting 21 2.5.1. - Interpretation of Fades and Fades Assodations 21 2.5.2. - Depositional Models for Sand Bodies Comprising the Fireweed, Cache Creek, West Stoddart and Buick Creek Pools 25 2.5.3. - Alternative Depositional Environments 31 2.5.3.1. - Tidal Inlets\/Barrier Islands 31 2.5.3.2. - Shelf Sheet Sands Incised by Tidal\/Storm Channels 31 2.6. - Structural Controls on Reservoir Distribution 32 2.6.1. - Regional Considerations 32 2.6.2. - Deposition of Doig Sands at Structurally Controlled Slope Breaks 35 2.6.3. - Structural Features form Log Data 35 2.6.4. - Syn-Sedimentary Growth Faulting 38 2.7. - Summary and Conclusions 40 2.8. - References Cited 42 C H A P T E R 3 - DIAGENESIS, RESERVOIR QUALITY AND PRODUCTION T R E N D S OF DOIG FORMATION SAND BODIES IN THE P E A C E RIVER A R E A OF W E S T E R N CANADA 3.1. - Abstract 46 3.2. - Introduction 47 3.3. - Lithology and Depositional Setting 49 3.4. - Database 52 3.5. - Petrology of Doig Sandstones 54 3.5.1. - Sandstone Composition 54 V 3.5.2. - Coquina Composition 55 3.5.3. - Diagenesis 55 3.5.3.1. - Calcite Cement 57 3.5.3.2. - Quartz 57 3.5.3.3. - Apatite 59 3.5.3.4. - Dolomite 59 3.5.3.5. - Anhydrite 59 3.6. - Paragenesis 61 3.6.1. - Early Calcite 61 3.6.2. - Fracturing and Microfaulting 63 3.6.3. - Formation of MoldicA\/uggy Porosity 65 3.6.4. - Compaction 65 3.6.5. - Replacement of Quartz by Carbonate 65 3.6.6. - Precipitation of Ferroan Calcite 66 3.6.7. - Carbonate Dissolution - Secondary Porosity 66 3.6.8. - Dolomite Precipitation 67 3.6.9. - Hydrocarbon Migration 67 3.6.10. - Geochemical Considerations 67 3.7. - Reservoir Quality 68 3.7.1. - Trend of Porosity and Permeability with Depths 70 3.7.2. - Bioclastic Facies and Calcite Cement Distribution 72 3.7.3. - Distribution of Secondary Porosity 72 3.8. - Production Trends 75 3.9. - Discussion 79 3.10. - Constraints on Exploration 82 vi 3.11. - Conclusions 85 3.12. - References Cited 86 C H A P T E R 4 - CONCLUSIONS 89 APPENDIX A - C O R E IDENTIFICATION AND LOCATION 92 APPENDIX B - C O R E DESCRIPTIONS 94 APPENDIX C - C A T A L O G U E OF THIN SECTION 186 APPENDIX D - C O R E ANALYSIS DATA 190 vii LIST OF FIGURES Figure 2.1. Map illustrating Doig penetrations within pools of the study area and cross-section locations 7 Figure 2.2. Stratigraphic framework for the study area 9 Figure 2.3. Facies associations within the Doig Formation at West Stoddart and Buick Creek 13 Figure 2.4. Section A-A' through West Stoddart field oriented parallel to depositional dip 15 Figure 2.5. Section B-B' through Fireweed, Cache Creek and West Stoddart fields, oriented perpendicular to depositional dip 15 Figure 2.6. Section C - C through Buick Creek field oriented perpendicular to depositional dip 17 Figure 2.7. Total Doig sand isopach within the study area 17 Figure 2.8. Core photographs of Facies 1a, 1c, 2a and 2b 18 Figure 2.9. Core photographs of Facies 2c, 2e and 2f 18 Figure 2.10. Sedimentary features in core photographs of the sandstone and bioclastic lithofacies 24 Figure 2.11. Sedimentological model for the Doig Formation at West Stoddart, Cache Creek and Fireweed fields, northeastern British Columbia 26 Figure 2.12. Dipmeter log through interpreted channel sandstones of the Cache Creek field 29 Figure 2.13. Structural elements intersecting the regional Doig sand trend 33 Figure 2.14. Structure contour map of the top of the Doig Formation upper phosphatic marker 34 Figure 2.15. Doig Formation isopach within the study area 36 Figure 2.16. Stratigraphic Section D-D' located in Fig 7 37 Figure 2.17. 3D seismic line showing middle Triassic growth fault at down-dip edge of the Fireweed delta complex 39 viii Figure 3.1. Location map of the study area showing the reservoir trend 48 Figure 3.2. Stratigraphic framework for the study area 50 Figure 3.3. Total Doig sand isopach within the study area 53 Figure 3.4. Core photographs of calcite cements in Doig Formation sandstone 56 Figure 3.5. Photomicrographs and S E M images of diagenetic phases in Doig Formation sandstones 58 Figure 3.6. Photomicrographs and core images of diagenetic features within Doig Formations sandstones 60 Figure 3.7. Generalized paragenetic sequence and porosity evolution of Doig Formation sand bodies 62 Figure 3.8. Fracture styles in Doig Formation sandstones..... 64 Figure 3.9. Core image and photomicrograph of compaction features 64 Figure 3.10. Graphs of core analysis data versus true vertical depth for various Doig pools 71 Figure 3.11. Map showing the distribution of bioclastic facies 73 Figure 3.12. Porosity\/Permeability cross-plots for Buick Creek and West Stoddart 74 Figure 3.13. Production cross-plots illustrating declines for the Buick Creek and West Stoddart pools 77 Figure 3.14. Map showing average daily oil and gas production for Doig pools along the reservoir trend 78 Figure 3.15. Map illustrating the constraints on exploration for Doig Formation sand bodies along the reservoir trend 83 ix LIST OF TABLES Table 2.1 : Lithofacies descriptions 11 Table 3.1. Lithofacies descriptions 51 Table 3.2. Average porosity and permeability values for select fields along the Doig reservoir trend 69 Table 3.3. Decline factors and average production for deviated and non-deviated wells in select fields along the Doig reservoir trend 76 X ACKNOWLEDGEMENTS I would like to thank my supervisor, Dr. Marc Bustin for all his guidance, patience and good advice during my term at The University of British Columbia. The 5 % payoff is more than compensation for rereading my Doig papers dozens of times. Thanks also to my supervisory committee, Dr. Kurt Grimm and Dr. Lori Kennedy and my external and head, Dr. Paul Smith and Dr. Richard Chase, for their time and interest. I am indebted to all the members of the sedimentary and geochemistry research group and my office mate Stuart Knoop for listening to all my sedimentological ramblings and giving sound advice and suggestions. Access to data and core were generously provided by the Oil and Gas Commission of the Government of British Columbia, International Datashare Corporation and Shell Canada. Corporate funding was provided by Shell Canada and the Alberta Energy Company. Seismic data was generously provided by Shell Canada. I would like to thank Tom Boreen and Kelvin Colquhoun at Shell Canada and Marc Edmonds at A E C West for their time, suggestions and contributions. Special thanks to Thomas Moslow of Ulster Petroleum for so thoroughly reviewing the second chapter. Chapter 2 also benefited greatly from the work of C .G . Welsh who evaluated the seismic data donated by Shell Canada in her honour's thesis at the University of British Columbia. Research and personal funding was provided by the Natural Sciences and Engineering Council of Canada (Bustin) grant, the Thomas and Marguerite Mackay Memorial Scholarship and a scholarship provided by the American Association of Petroleum Geologists. Many thanks to the UBC geology staff and technicians for there timely support and sample preparation. Many others (too numerous to name) contributed to my research and my happiness during my stay at UBC Thank You. Finally I would like to thank an extend my deepest gratitude to my significant other, Marcy Robertson, whose tireless enthusiasm, love and spirit lent me the strength to finish this work before it finished me. CHAPTER 1 Introduction 1.1. - INTRODUCTION Recent hydrocarbon discoveries in marine sand bodies of the Triassic Doig Formation have significantly expanded oil and gas production from this interval in Northeastern British Columbia. An understanding of the factors that control the distribution and reservoir quality of Doig sand bodies is required in order to reduce the risk in further exploration. The purpose of this thesis is to provide depositional and structural models for Doig pools in northeastern British Columbia and to establish the relationship between diagenesis and reservoir quality and production for Doig pools along the entire reservoir trend in western Canada. Doig pools with core examined in this study are located in northeastern British Columbia (Fig. 1) between 94-A-13 (NW) and Township 87, Range 19 (SE) west of the 6th Meridian. The area of study extends from the Tommy Lakes field in northeastern British Columbia to the Valhalla field in west central Alberta. Since the first major discovery at Buick Creek, production from this trend in British Columbia has been approximately 20.6 x10 6 m 3 oil and 20.0 x 10 6 E 3 m 3 gas (Govt, of BC data, July, 1999). Doig reservoir rocks are clean fine-grained sub-lithic to quartz arenites and bioclastic wackestones to packstones up to 30 m thick with porosity values up to 20%. Doig pools are characterized by erratic production declines and an uneven distribution of effective porosity. The general depositional framework for the Doig Formation in the Western 1 Canada Sedimentary Basin (WCSB) has been established by previous regional studies (Gibson and Edwards, 1990, Davies, 1997). Depositional models for specific Doig pools have been examined at Wembley, Valhalla and Sinclair in Alberta (Cant, 1986 and Wittenberg, 1992) and Buick Creek in British Columbia (Munroe and Moslow, 1991, Evoy and Moslow 1995, and Evoy, 1997). No previous study documents the paragenetic history of Doig sand bodies and establishes the links between diagenesis and reservoir quality or production history of Doig reservoirs. 1.2. - STRUCTURE OF THESIS This thesis is presented as two stand-alone papers which may be read without reference to preceeding chapters. Chapter 2 investigates the depositional and structural controls of Doig Formation sand bodies in northeastern British Columbia with emphasis on the Buick Creek, Cache Creek, West Stoddart and Fireweed pools. The objectives of this chapter are to: a) document the lateral and vertical facies relationship of the sand bodies and enclosing lithologies; b) provide an environmental interpretation of facies and facies associations; c) develop a depositional model encompassing the four pools and; d) examine the role of structure in the distribution of reservoir facies. Chapter 3 investigates the link between diagenesis and reservoir quality and production history of reservoirs located along the Doig sand body trend in British Columbia and Alberta. The objectives of this chapter are to: a) document the petrology of Doig sandstones; 2 b) place diagenetic components into a paragenetic sequence; c) examine the relationship between diagenesis and reservoir quality in terms of core porosity and permeability; d) examine the relationship between diagenesis and hydrocarbon production and; e) constrain an exploration \"fairway\" for future Doig sand body exploration. 1.3. - REFERENCES CITED Cant, D.J., 1986. Hydrocarbon trapping in the Halfway Formation (Triassic), Wembley Field, Alberta. Bulletin of Canadian Petroleum Geology, v.34, p.329-338. Davies, G.R., 1997. The Triassic of the Western Canada Sedimentary Basin: tectonic and stratigraphic framework, paleogeography, paleoclimate and biota. Bulletin of Canadian Petroleum Geologists, v45, p.434-460. Evoy, R.W. and Moslow, T.F., 1995. Lithofacies associations and depositional environments in the Middle Triassic Doig Formation, Buick Creek Field, northeastern British Columbia. Bulletin of Canadian Petroleum Geologists, v43, p. 461-475. Evoy, R.W., 1997. Lowstand shorefaces in the Middle Triassic Doig Formation: implications for hydrocarbon exploration in the Fort St. John area, northeastern British Columbia. Bulletin of Canadian Petroleum Geologists, v45, p537-552. Gibson, D.W. and Edwards, D.E. 1990. An overview of Triassic stratigraphy and depositional environments in the Rocky Mountain Foothills and Western Interior Plains, Peace River Arch. S .C. O'Connell and J .S . Bell (eds.). Bulletin of Canadian Petroleum Geology, v.38, p. 146-158. Munroe, H.D.and Moslow, T.F., 1991. Depositional Models for the Doig Formation of northeastern British Columbia (abstract). Opportunities for the Ninties, Canadian Society of Petroleum Geologists Convention, Calgary, Alberta, Program and Abstracts, p105. Wittenberg, J . , 1992. Origin and stratigraphic significance of anomalously thick sandstone trends in the Middle Triassic Doig Formation of west-central Alberta. Unpublished M.Sc. thesis, University of Alberta, Edmonton, Alberta. 600p. Munroe, H.D.and Moslow, T.F., 1991. Depositional Models for the Doig Formation of northeastern British Columbia (abstract). Opportunities for the Ninties, Canadian Society of Petroleum Geologists Convention, Calgary, Alberta, Program and Abstracts, p105. 3 CHAPTER 2 Depositional and Structural Models for Doig Formation Sand Bodies in the Peace River Area of Northeastern British Columbia 2.1 . -ABSTRACT Middle Triassic Doig reservoirs in the Fireweed, Buick Creek, Cache Creek and West Stoddart fields (94-A-13 to Twp.86, Rge.18) of northeastern British Columbia consist of deltaic to shoreline sands encased in shelf and offshore mudstones and siltstones. The reservoirs are a series of northwest and northeast trending elongate sand bodies, up to 50 metres thick, incised into a south trending sand sheet with a maximum thickness of 15 metres. Sediments of the Doig formation are divisible into two facies associations and ten lithofacies representing deposition in shelf to offshore, and deltaic and inter-deltaic environments. Producing intervals consist of clean, very fine to fine grained, sub-lithic to quartz arenites, interbedded sandstones and both disseminated and bedded bioclastic detritus. The sedimentology and facies architecture of recent discoveries at Cache Creek and West Stoddart contrast with those identified in previous studies of Doig reservoirs at Buick Creek in northeastern British Columbia and Sinclair in west central Alberta. A three-dimensional facies model of the Doig Formation at the Cache Creek, West Stoddart and Fireweed fields depicts sandstone deposition in a deltaic environment as distributary channel fills and slumped delta front deposits. Data for the Buick Creek field 4 confirms and extends the incised shoreface model to include contemporaneous fluvial or tidal channels deposited laterally continuous with the shoreface sands. Sand bodies for all four fields were deposited contemporaneously as the Doig shoreline prograded over mudstones and siltstones of the Doig shelf. Seismic and well data reveal tectonic control on the position and orientation of the Doig reservoir trend. Syn-sedimentary growth faults control the location and geometry of thick sand bodies along the reservoir trend in the Fireweed area. 2.2. - INTRODUCTION The recent discoveries of the West Stoddart and Cache Creek hydrocarbon pools in northeastern British Columbia have significantly expanded oil and gas production from marine sandstone of the Middle Triassic Doig Formation. Doig reservoir rocks are clean fine-grained sub-lithic to quartz arenites and bioclastic wackestones to packstones up to 30 m thick with porosity values up to 20%. A general depositional framework for Doig sandstone reservoirs in the Western Canada Sedimentary Basin (WCSB) has been established by regional studies (Gibson and Edwards, 1990, Davies, 1997), and detailed studies of specific Doig pools at Wembley, Valhalla and Sinclair in Alberta (Wittenberg, 1992) and Buick Creek in British Columbia (Evoy and Moslow 1995, and Evoy, 1997). The purpose of this paper is to provide a depositional model for the Doig pools of the Fireweed, Cache Creek, West Stoddart and Buick Creek fields of northeastern British Columbia by describing the sediments, the facies architecture and the structural controls on sand body distribution. This study gives an alternative depositional model for the \" 2 n d Doig sand\" described by Evoy (1997) and suggests that the reservoir sandstones comprising the Buick Creek, Fireweed, Cache Creek and 5 West Stoddart fields were deposited within the same systems tract. The diagenesis and reservoir characteristics of Doig reservoirs are examined in a subsequent paper (Harris and Bustin, in prep.). The study area is located in British Columbia (Fig. 1) between 94-A-13 (NW) and Township 87, Range 19 (SE) west of the 6th Meridian. The regional trend examined in this study (Fig. 1) extends from the Tommy Lakes field in northeastern British Columbia to the Valhalla field in west central Alberta. Analyses performed in this study include the examination of 42 cores, 72 thin sections, well logs for over 300 wells, core analysis data and production data for 27 wells within the study area and 11 additional wells along depositional strike of the reservoir trend. Structural data includes 1 regional and 3 local cross-sections constructed by the author and 2d and 3d seismic data. 2.3. - GEOLOGIC SETTING The study area is located on the southwest dipping, northern flank of the \"Peace River Basin\" (PRB), a major structural low formed in Mississippian time (Davies, 1997). Periodic reactivation and continued subsidence of the P R B throughout the late Paleozoic and Mesozoic led to formation of a thick sedimentary succession, including over 1200 m of Triassic sediments in the western foothills of the Rocky Mountains. Triassic strata comprise a westward thickening wedge of shelf and marginal marine siliciclastics, carbonates and evaporites. These Triassic strata were deposited on what was initially believed to be the tectonically stable continental shelf of the western margin of the passive North American craton (Gibson and Barclay, 1989). Recent studies (Qi, 1995, Caplan and Moslow, 1997, Davies, 1997) suggest that 6 7 tectonism played an important role in the deposition and preservation of reservoir facies within the Triassic sequence, which is further explored in this study. The study area (Fig. 1) was located in a mid-latitudinal position, in an arid, sediment starved environment (Davies, 1997) during the Middle Triassic. Faunas are limited in Doig strata which suggests either restricted marine conditions or an enduring effect of the Permian extinction event. Hydrocarbon production in middle Triassic sediments within the study area is from shoreface and terrestrial sandstone of the Halfway, Doig and lower Charlie Lake formations which are part of a major transgressive-regressive sequence within the Triassic period (Embry, 1997). Separate nomenclature systems have been developed for Triassic rocks in outcrop (Gibson,1974,1975) and in the subsurface (Gibson and Barclay, 1989) (Fig. 2). In this study, subsurface nomenclature has been adopted with contacts between formations based on log markers and core information. Phosphatic mudstones and siltstones of the Doig Formation rest on the 2 n d order sequence boundary identified by Embry (1997) on top of Montney shelf sediments. Young (1997) gives a summary of the controversial contact between the Halfway and Doig Formations; in the majority of published descriptions the contact is considered conformable and regressive. The contact between the Doig and Halfway Formations is conformable in the study area, but becomes erosional to the east. The base of the Doig Formation is here picked at a radioactive muddy siltstone, which is a regional marker unit termed the phosphate zone (Wittenberg, 1992). Above the phosphate zone, the Doig Formation consists of a succession of mudstone, siltstone, very fine-grained sandstone, and fine-grained sandstone and bioclastic beds. 8 00\/11-35-087-22W6 - SUNCOR CACHE CREEK Period\/Epoch\/Age GR Depth (m) Stratigraphy Sequence Stratigraphy Environment of Deposition Late Carnian H 5 2 5 ^ Upper Charlie Lake Formation 2\"\" SB Coplin Unconformity - 1550 -1575 Lower Charlie Lake Formation Highstand Systems Tract tidal flat evaporites, carbonates and sandtone Ladinian SSIC -1600 Halfway Formation shoreface sandstone SSIC CO T3 T3 -1625 MFS shelf\/offshore siltstone\/sandstone < i FS TST TRI -1650 Doig Lowstand Systems Tract 3RTSB deltaic\/shoreface sandstone - 1 6 7 5 Formation Highstand Systems Tract MFS mudstone Anisian --1700 shelf\/offshore phosphatic mudstone\/ Phosphatic Zone TST 2MSB siltstone\/sandstone Early Spathian - 1 7 2 5 - 1 7 5 0 Montney Formation Highstand Systems Tract shelf siliciclatics Fig. 2.2 - Sequence Stratigraphic framework and environments for Triassic strata within the study area (modified from Gibson and Barclay, 1989 and Gibson and Edwards, 1990). TST - transgressive systems tract, M F S - maximum flooding surface, FS -flooding surface, 2 n d\/3 r c l S B - second\/third order sequence boundaries. 9 2.4. - LITHOSTRATIGRAPHY AND SAND BODY GEOMETRY The Doig Formation within the study area (Fig. 2) comprises one 3 order sequence and the lower portion of another 3 r d order sequence. The lower sequence is bounded by unconformities at the base the Doig Formation (Edwards et al., 1994) and at the base of the Doig sand unit (Evoy and Moslow, 1995). The remainder of the Doig is made up of a lowstand systems tract representing reservoir sandstones and a transgressive systems tract bound at its upper extent by a flooding surface and the onset of highstand and progradation of Halfway sands. The Doig Formation comprises mudstones, siltstone and very fine-grained sandstones enclosing the fine-grained sands and bioclasts of the Doig sand bodies. Generally there is a single sandstone unit within the Doig Formation, however vertically stacked sand units separated by mudstone intervals do occur. The finer grained clastic units are interpreted as marine shelf and offshore deposits. A regression of the Doig shoreline onto the Doig shelf is interpreted to have been responsible for deposition of the sand unit. Doig sandstones are sharply overlain by siltstone, mudstone and sandstone interpreted to represent a flooding surface and a transgressive systems tract. Sediments of the Doig Formation are divided into ten lithofacies that are grouped into two facies associations (Table 1), representing shelf and offshore, and deltaic and shoreface deposits. In the following section the lithology and stratigraphy of the Doig formation is described and illustrated in sections A-A', B-B', and C-C (Figs 4,5 and 6). A summary of facies and facies associations identified in this study are provided in Table 1. Other detailed 10 Facies Assoc. Facies Description a Laminated Mudstone dark grey to black mudstone and siltstone, planar laminated, organic-rich, calcareous, rare vfg sandstone laminae, abundant fractures and pyrite, absence of body and trace fossils i b Bioclastic Mudstone dark grey to black brachiopod packstone, massive, calcareous, matrix dominantly muddy, rare silty to vfg sandstone, bioclasts are typically delicate non-abraded brachiopod plus minor pelecypod and echinoderm debris I c Laminated Siltstone dark to medium grey siltstone and vfg sandstone, planar to wavy laminated, cm scale convolute inter-bedded vfg sandstone, calcareous, abundant cut-and-fill structures, rare Hz traces, scattered echinoderm and brachiopod debris a Muddy Sandstone light grey vfg quartz sandstone and mudstone, ripple laminated to x-bedded, abundant cut-and-fill structures, load casts, mudstone rip-ups, calcareous, moderately abundant horizontal traces, synaeresis cracks, rare bivalve fossils b Massive Sandstone brown to light grey vfg-fg quartz sandstone, massive, moderately sorted, sub-angular, calcareous, abundant mudstone rip-ups, calcite cements visible as concretions, traces absent, rare abraded bioclastic debris c Laminated Sandstone brown to light grey vfg-fg quartz sandstone, low to high angle laminated to x-laminated, H C S , moderately sorted, subangular, calcareous, abundant mudstone rip-ups, calcite cements visible as concretions or in zones following primary structure, rare bioclastic debris and traces. 2I,II d Bioclastic Sandstone light grey vfg-fg quartz sandstone as above with 20-30% coarse sand to pebble sized abraded bioclastic debris, massive to planar laminated, abundant visible intergranular calcite, rare vuggy porosity, traces absent e Interbedded Sandstone\/Coquina brown to light grey vfg-fg quartz sandstone as in 2c interbedded with pelecypod coquina, abraded bioclasts, abundant lithic clasts and mudstone rip-ups, abundant visible calcite appears related to bioclastic material, coquina can appear as isolated lenses or breccia clasts in a sandstone matrix, rare traces f Coquina light grey coquina, 60-90% abraded bivalve bioclasts in a fg quartz sandstone matrix, x-bedded (normal and inverse), moderately to poorly sorted, bioclasts moderately imbricate, abundant mudstone rip-ups, visible intergranular calcite, traces absent g Mudstone Breccia Granule to pebble breccia, mudstone clasts in a vfg -fg quartz sandstone matrix, imbricate, rounded to angular clasts, poorly sorted, mudstone, semi-lithified deformation structures, rare bioclastic debris, traces absent Table 2.1 - Facies Descriptions stratigraphic sections and facies descriptions for the Doig Formation can be found in Wittenberg (1992), Evoy and Moslow (1995) and Evoy, (1997). 2.4.1. - FACIES AND FACIES ASSOCIATIONS Sediments of association 1 are composed of fine-grained mudstone, siltstone and very fine-grained sandstone that act as both seals and source rocks to the reservoirs of association 2. Facies association 2 consists of very fine-grained to fine-grained quartz sandstone, coquina and mudstone. Facies association 2 can be further sub-divided into associations 2i and 2ii based on vertical lithofacies stacking. Facies association 2i (Fig. 3b) is a coarsening upward package of fine-grained sandstone and mudstone facies which erosively overlie and underlie the sediments of association 1. Facies association 2ii (Fig. 3a) is a massive to fining upward package of fine-grained sandstone, coquina and bioclastic sandstone facies erosively overlying association 1. At Buick Creek, associations 2i and 2ii are laterally equivalent. Previous interpretations by Evoy and Moslow (1995) placed deposition of association 1 in a distal to proximal shelf environment and association 2 in an offshore to upper shoreface environment. Interpretations from this study are in agreement but expand association 2 to include deltaic deposits. 12 a ) WEST STODDART - 14-31 -87-21W6 Depth(m) G R LOG 1615 1625 LITHOLOGY 1635 1645 1655 1665 not cored A A A A A A * \u2022 \u2022. \u2022\u2022) \u2022 & ' ' . . e> \u2022 ' .CP\/ \u2022J . c? . \u2022 \u2022 i> '?' \u2022 \\
l Facies 2f fc