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Investigations of NMR T1 relaxation mechanisms in oil- and water-wet sand packs Caputi, Michael Burns 1997

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INVESTIGATIONS O F N M R T1 R E L A X A T I O N M E C H A N I S M S IN OIL-A N D W A T E R - W E T SAND P A C K S by MICHAEL BURNS CAPUTI B.Sc. Geology, California State University Northridge, 1995 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREEE OF MASTER OF SCIENCE in THE F A C U L T Y OF GRADUATE STUDIES DEPARTMENT OF E A R T H AND OCEAN SCIENCES - GEOPHYSICS We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA DECEMBER, 1997 © Michael Burns Caputi, 1997 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 of the University of British Columbia Vancouver, Canada Date DE-6 (2/88) Abstract The proton N M R relaxation parameter T , is affected by both relaxation in the bulk pore f lu id and relaxation associated wi th the surface o f the pore space. A n understanding o f the relative importance o f these two relaxation mechanisms is a critical part o f interpreting the N M R response of f lu id saturated porous rocks. The first part o f the thesis was an experimental study o f the relaxation o f protons in a sand pack f i l led wi th pyrite. B o t h o i l - and water-wet sand packs exhibited a decrease in relaxation times of the pore f lu id as the amount o f pyrite in the sand was increased. I believe that the oxidation product o f pyri te , F e 3 + , is the critical component in governing the relaxation mechanism in these sand packs. The F e 3 + is go ing into solution and f i l l i n g the pore f l u id , decreasing the bulk solution relaxation time o f the pore f lu id . The F e 3 + is also believed to be adsorbing to the oil-water and water-sand interfaces, enhancing the surface-induced relaxation mechanisms in the o i l - and water-wet sand packs. The second part o f the thesis concentrated on understanding relaxation mechanisms in o i l -and water-wet sand packs with pore fluids o f differing p H and salinity. Changes in salinity of the pore f lu id proved to have no effect on either the bulk solution or surface-induced relaxation mechanisms. L o w p H pore f lu id in the o i l - and water-wet sands appears to br ing paramagnetic species f rom the oil-water and water-sand interfaces into solution, decreasing bulk solution relaxation times o f the pore fluids. The magnitude o f the surface-induced relaxation mechanisms, quantified by determining the surface relaxivi ty , also increases i n strength wi th the decrease in pore f l u id p H . ii Table of Contents Abstract ii Table of Contents iii Acknowledgments iv Investigations of T t relaxation mechanisms on water-saturated oil- and water-wet sand packs mixed with pyrite 1. Introduction 1 2. Experimental Procedure 4 3. Experimental Results 7 4. Discussion 11 5. Conclusions 16 Investigations of T } relaxation mechanisms on oil- and water-wet sand packs saturated with acidic, alkaline, and saline water 7. Introduction 18 8. Experimental Procedure 22 9. Experimental Results 31 10. Discussion 39 10.1 Water-wet sands 39 10.2 Oil-wet sands 43 11. Conclusions 44 12. References 47 Appendix A - Sample number listing for figures in pyrite section 49 Appendix B - NNLS results for each sample in pyrite section 5 3 Appendix C - Sample number listing for figures in pH/saline section 68 Appendix D - NNLS results for each sample in pH/saline section 74 Appendix E - Scanning electron photomicrographs of Ottawa sand 144 iii Acknowledgments This research was supported primarily through funding to Rosemary Knight from an Imperial Oil University Research Grant; from Esso Resources Canada, Conoco, Petro-Canada; and from an NSERC Industrially Oriented Research Grant. Additional funding was provided through a grant from the U.S. Department of Energy. The NMR lab was also supported by an Individual Research Grant to Alex MacKay from NSERC. iv Investigations of Tj relaxation mechanisms on water-saturated oil- and water-wet sand packs mixed with pyrite 1. Introduction Proton nuclear magnetic resonance (NMR) relaxation utilizes the interaction between the magnetic moments of protons and a magnetic field. At equilibrium, the moments from the net magnetization will almost align with an external magnetic field H 0 . The moments precess about H 0 at an angular frequency co, represented by the following equation co = Y * H 0 (1), where y is the gyromagnetic ratio of hydrogen. Viewing the system in the rotating frame allows the collection of moments rotating at CO to be simplified to a single net magnetization vector in the +z'-direction. Relaxation experiments begin by using M in this equilibrium state. There are two types of relaxation used in NMR: T,, or longitudinal relaxation, and T 2, or transverse relaxation. M is rotated from the equilibrium state to the -z'-direction to begin our modified inversion-recovery T, measurement. M is then measured as it returns to the +z'-direction. The rate of return of the magnetization to the +z'-direction is 1/T,. Other researchers use 1/T2, the dephasing rate of the signal M from the +y'-direction. My research uses T, relaxation only, leaving the collected T 2 data to be reviewed at a later time. Relaxation of protons in the bulk solution is a result of the influence of all the other protons and aqueous constituents in the solution. When a proton travels about the bulk solution, it passes through magnetic fields of the other protons and constituents in the solution. This magnetic influence from the surroundings increases the likelihood that the unrelaxed proton will relax and 1 align again with H 0 . If the bulk solution contains paramagnetic ions, the relaxation time of the paramagnetic ion-filled solution will be relatively short. When water protons are confined in a small space, such as in a rock's pore, the confining space's walls become important in the relaxation process. If the walls are coated with oil, as with an oil-wet rock, the solid surface contributes significantly less to relaxation processes. As a result, the relaxation time of water protons in most oil-wet rocks will be close to bulk solution relaxation times, about 3 s or more. However, recent research shows that the oil-wet surface may be more important in the relaxation process. Kanters (1996) showed that the T, of oil-wet sand was a function of pore size; a trend that suggests surface relaxation may be a factor in oil-wet sands. On the other hand, if the walls are water-wet, the pore walls are definitely a factor in the relaxation process. During a relaxation experiment, unrelaxed protons will travel throughout the pore space, colliding many times with the pore wall. Every collision with the wall increases the probability of relaxation of the unrelaxed proton. The time for proton relaxation is inversely proportional to the surface area to volume ratio (S/V) of the pore space. The measurement of N M R relaxation is a useful way to obtain pore-size distributions (Straley et al., 1995). The magnetization decay rate from a modified inversion recovery experiment follows M(t) = M(0) * exp -(t/T,) (2), where M(t) is the net magnetization of the protons in a pore, M(0) is the net magnetization at time zero, and T,, the relaxation time constant, is 1/T,= p * (S/V) + 1/Tlb (3), 2 where p is the surface relaxivity of the pore wall and T l b is the relaxation time of the pore fluid in bulk. This equation is only valid if the sand pack under question is in the fast-diffusion regime (Kleinberg, 1994). This means that the relaxation process is controlled by the surfaces of the pores and not by the time for diffusion of protons to the pore walls. Work done by Kanters (1996) showed that relaxation processes with sand packs of this type were in the fast-diffusion regime. Studies of p have contributed much to the rock relaxation theories. Korringa, Seevers and Torrey (1962) calculated that paramagnetic ions adsorbed to pore walls are the primary relaxation site for pore fluid protons. Later, with a study on synthetic silicates, Foley et al. (1996) showed that the presence of broken-bond sites on the mineral surface of the pore wall was also an effective rock relaxation site. These broken-bond sites in the pore wall, with their unpaired electrons, have a paramagnetic character that makes them very similar to paramagnetic ions adsorbed to the surface of the pore walls. Both the adsorbed and broken bond paramagnetic sites contribute to relaxation of protons in a rock's pore. One could conclude from the above discussion that the more paramagnetic sites available for proton relaxation in a rock the shorter rock relaxation time for pore fluid in a rock; and hence the greater the surface relaxivity. However, surface relaxivity studies have shown that as surface paramagnetic content increases, p changes little and ultimately reaches an upper-limiting value (Kenyon and Kolleeny, 1995; Foley et al., 1996) From the above discussion, paramagnetic ions appear to be an important factor in rock relaxation. Common sedimentary rocks contain 1% heavy minerals. These minerals are loaded with metal atoms that, once extricated from the heavy mineral, oxidize to a paramagnetic ion. Let us consider, for example, the oxidation of pyrite, a common heavy mineral: 150 2 ( a q ) + 4FeS 2 ( s ) + 2H 2 0 <z> 4Fe 3 + ( a q ) + 8 S 0 4 2 U q ) + 4 H + ( a q (4). When the pyrite is exposed to water and oxygen, iron is leached from the mineral. The iron, as are most metals, is very unstable with a full-electron-outer-shell. The metal then becomes a metal ion 3 Fe 3 + ( a q ) because the metal loses its excess electrons to the surroundings. The Fe 3 + ( a q ) is now free to interact with either the pore water or the pore walls. My approach in this research was to document any changes in NMR T, as pyrite concentration increased from 0 to 5% by volume in both water- and oil-wet sand packs. My goal was to determine if estimated surface relaxivities from water-wet sands remain relatively constant over a wide range of included Fe 3 + ( a q ) , a common paramagnetic ion. This research, in combination with a host of other NMR studies on adsorbed paramagnetics (Kenyon and Kolleeny, 1995; Foley, 1996), will hopefully show that p changes little with significant increases in paramagnetic ions. 2. Experimental Procedure All sand packs in this study consisted of Ottawa sand; chosen because the sand has 99.8% Si0 2, spherical grains, and 0.01% impurities. The 120-140 U.S. mesh sized sand (115 urn average diameter) was magnetically cleaned with an electromagnet: a Frantz Isodynamic Separator. Dark-colored and opaque sand grains 0.5% by weight were removed with the Frantz Separator. The cleaned sand was then boiled in 10% nitric acid, rinsed in distilled water, and oven-dried. This was to ensure that any surface contamination of adsorbed paramagnetic ions was removed from the sand. We consider this resulting sand to be water-wet. Oil-wet sand was prepared as part of the study by Kanters (1996). Cold Lake crude oil, a viscous and petroporphyrin-rich oil from Alberta, Canada, was used as the oil phase. V 0 2 + and organic free radicals make up most of the petroporphyrin content of the oil (Semple et al., 1990; Khulbe et al. 1996). The oil-wetting procedure for the sand is as follows. The unseparated Ottawa sand was first washed with 0.1 M HC1, rinsed with distilled water, and soaked in a 0.02 M NaCl / pH 2.5 solution. After drying in an oven, the sand was added to the crude oil and cooked for 14 days at 80° C. The sand was then rinsed with n-Heptane and dried. 4 Two sets of experiments were conducted to determine the effect of pyrite on N M R relaxation times. In the first set, oil- or water-wet sand grains and pyrite grains were packed into Teflon™ sample holders. Pyrite was mixed with water-wet sand at steps of 0.5% by volume from 0 to 2%. Pyrite was also mixed at 3, 4, and 5% with water-wet sand. Oil-wet sand was mixed with 0, 2, and 5% pyrite. The packs were then evacuated to 60 mm of Hg and saturated with degassed distilled water. The second set of experiments were conducted on bulk degassed solutions that were mixed with, and extracted from, water-wet sand and pyrite. These two solutions, one from 100% water-wet sand and the other from 5% pyrite and water-wet sand, were then analyzed to obtain relaxation times and total dissolved iron content. I consider these two solutions to represent the pore water from water-wet sand packs mixed with 0 and 5% pyrite. Both sets of N M R relaxation experiments were conducted within 48 h of degassing. T, relaxation times for both sets of experiments were collected using a pulsed proton NMR spectrometer. The spectrometer is a Bruker iron-core electromagnet with an SXP™ probe of 10 [is deadtime. The spectrometer's 2.12 Tesla magnetic field strength generates a 90 MHz precessional frequency for hydrogen. A modified inversion-recovery pulse program was used for measuring T, relaxation. Water loss from the samples was considered because the experimental temperature ranged from room temperature to slightly above room temperature. After measuring the amplitude of the net magnetization both before and after each sample run, and noticing negligible differences in the net magnetization, it was concluded that no water was lost. In N M R relaxation studies, M is rotated by H, , a radio frequency electromagnetic field using a sample coil. The length of time electricity is switched on to create H , is referred to as the pulse length. Rotating M 90° and 180° in these experiments, needed for a T, relaxation time inversion-recovery collection, required 2.2 and 4.4 [is pulse lengths, respectively. 5 The decay of net magnetization in our sand packs was collected using a modified inversion-recovery pulse sequence that is represented by the following: 90° and 180°-T-90°. Part one, or 90°, is a measure of M in the +y'-direction after M is allowed to achieve equilibrium with the H 0 or +z'-direction. The 90° signifies the rotation angle of M from the +z'-direction to the +y'-direction. Part two, or 180° - % - 90°, is slightly more complicated than part one. The second part of the pulse sequence is performed with 15 separate T values. Each pulse sequence with each T goes as follows: M is initially in the equilibrium state before being rotated to the -z'-direction (180°), then time t is waited before the remaining M is rotated to the y'-direction (90°) where M is measured. Each of the 15 M values from part two is then subtracted from the M of part one to obtain a net magnetization decay curve that represents the sand pack's relaxation of the pore fluid. Using the rock's decay curve for pore space information is straight-forward if we assume all the pores of size i in the equation M(x) = Z i [P^expC-T/T.i)] (5) relax independently of other-sized pores; % is the time between the 180° and 90° pulses in the above inversion recovery pulse sequence, and P{ are the associative amplitudes. P ; is proportional to the amount of water with T, time T H . This means that each pore size relates directly to a specific T,. 6 Equation 5 was solved by the nonnegative least squares methods outlined in Whittall and MacKay (1989). T, ranged from 1 ms to 10 s, a range comparable to that used in Kenyon (1992) for sandstones. The recovered T n and Pj values were averaged for a logarithmic mean T, (Fordham et al., 1995), according to the following equation Logarithmic mean T, = exp { £ s [Pi * loge(Th)] / £=_ Pj } (6). 3. Experimental Results Figure 1 shows the decreasing trend of T, values for the oil-wet sands saturated with water and mixed with increasing pyrite. The largest decrease in T, occured for the pyrite increase from 0 to 2%. Figure 2 shows the T, results for the water-wet sand mixed with pyrite. Relaxation time decreased as pyrite increased from 0 to 5%. The water-wet sand T, values tended to reach a lower limit at about 0.4 s when pyrite content was increased past 1%. The largest decrease in the water-wet sand pack T, values occured between 0 and 1 % added pyrite. Figure 3a shows the T, values recorded for the two bulk solutions from the second set of experiments. These pore water representations had T, relaxation times that are inversely proportional to the amount of pyrite in the sample. The bulk water solution that was only in contact with water-wet sand had a T, value of 3 s. The bulk water solution from the 5% pyrite/water-wet sand mixture exhibited a 33% decrease in T,. The accompanying figure 3b shows the results for the chemical analysis done on the two water solutions just described. The 5% pyrite/water-wet sand-related bulk water contained 6 times the dissolved iron found in the bulk water from the water-wet sand. The 0.6 PPM of dissolved iron value for the pyrite/water-wet sand water sample was considerably less than the solubility limit of pyrite (5 PPM of dissolved iron) in water. Appendices A and B describe the data from figures 1, 2, and 3a in greater detail. 7 2 3 4 percent pyrite added Figure 1. T, of pore water in oil-wet sand and pyrite. 8 1 2 3 4 percent added pyrite Figure 2. T , of pore water in water-wet sand and pyrite. 9 3.50E+00 3 .00E + 00 2.50E+00 + -5T 2 .00E+00 J— 1.50E+00 1 .OOE+00 5 .00E-01 0.OOE+00 0 1 2 3 4 percent added pyrite o 1 .00E-01 °- 0.OOE + 00 1 2 3 4 percent added pyrite Figure 3. A) Bulk solution Tj of pore water from water-wet sand and pyrite Total dissolved iron of pore water in figure 3a. 10 To see if the paramagnetics related to the oil petroporphyrins become pore water soluble, I mixed water, pH 5, with oil-wet sand. This water was extracted and measured for its T l b , exactly as described above for the second set of experiments. T l b was found to be exactly the same as bulk water, about 3 s. To use equation 3 for an accurate calculation of surface relaxivity, I must first relate the surface to volume ratio of the grains to the pore surface-to-volume. This reconfiguration of the S/V is detailed in the thesis done by Kanters. The Kanters reconfiguration sets the S/V of the pore space equal to [6*(l-()>)]/ (0 *d) where <j) is the porosity of the sand pack (0.375) and d is the diameter of the unimodal sand grains. T, b as a function of pyrite is obtained from figure 3a by linearly interpolating T, values between T, values for 0 and 5% pyrite added. Figure 4 presents the calculated surface relaxivity as a function of pyrite. p increased as pyrite content increases from 0 to 1%, ranging from 1.2 x 10 3 cm/s to about 2.0 x 10"3 cm/s. p then reached an upper limit, leveling off after 1% added pyrite at about 2.4 x 10 3 cm/s. Error estimates of T[ are difficult to obtain for individual sand packs because only one T, was measured for most of the samples. However, based on 15 T, measurements of a clean sand saturated with distilled de-aired water (pH about 5.1), estimated errors are +/- 0.1 s. 4. Discussion As has been shown in the preceding figures, T, decreases as the amount of pyrite increases. Water-saturated T, values for the oil-wet sand decreased by 40% with as little as 2% added pyrite, while T, decreased by 41% when only 1% pyrite was added to water-wet sand packs. Bulk water solutions from the pyrite/water-wet sand of the second set of experiments decreased by 33% as the pyrite content increased from 0 to 5%. 11 3 o i 2 1.5 0.5 2 3 percent pyrite added Figure 4. Calculated surface relaxivity for water-wet sand and added pyrite 12 First, pore water bulk solutions taken from the pyrite/water-wet sand packs will be discussed. Figures 3a and 3b show that the bulk solutions are decreased in T, relaxation time and increased in dissolved iron as the amount of added pyrite increased. Other researchers have shown that increasing the soluble paramagnetic ion content of a water solution decreases relaxation time. Therefore, with the increase in dissolved iron through the oxidation of pyrite, I believe the pore water bulk solutions for both water- and oil-wet sands packs are increasing in Fe 3 + ( a q ) and subsequently decreasing in T,. As described in the preceding paragraph, I believe that increased Fe 3 + ( a q ) concentrations in the pore water are the primary NMR relaxation process of T l b . However, the high content of paramagnetic petroporphyrins in Cold Lake crude (V0 2 + and organic free radicals) could also affect NMR relaxation processes if they become water soluble. Also, since T l b of the pore water from the oil-wet sand is exactly the same as the T l b of bulk water; about 3 s, I conclude that the sole contributor to the bulk relaxation properties of the pore water mixed with oil-wet sand and pyrite must be the increased Fe 3 + { a q ) concentration. The preceding paragraphs in this section outline the bulk solution relaxation in our samples. However, relaxation of pore water by a rock is controlled by both bulk solution and surface relaxation mechanisms. Before discussing the processes by which the sand surfaces are contributing to the relaxation of pore water, a brief review of surface chemistry and physics with respect to sand and water is needed. Schindler et al. (1976) performed adsorption experiments to better understand the silica-water interface. Their results show that Fe 3 + completely adsorbs to the silica-water interface by about pH 3.5 (Fig 5). This is significant for our studies presented here for two reasons; 1) quartz and silica are substances that are used interchangeably, therefore results from Schinder et al. researchers can be used for our quartz sand, and 2) it shows that if ferric iron is present in the pore water of our sand packs, it will completely adsorb to the sand-water interface. 13 Figure 5. Percent adsorption of Fe3+, Pb2+, Cu 2 + , and Cd 2 + onto silica gel as a function of -log[H+] (Schindler et al.,1976). 14 Another N M R study, a study that focuses on the surface concentration of Fe in synthetic silicates, can help explain the results presented here. Foley et al. (1996) calculated surface relaxivity values for their silicates doped with known amounts of surface Fe. Two trends in their surface relaxivity data help explain the conclusions we made earlier about adsorbed Fe 3 + becoming a site of enhanced relaxation. Foley et al. (1996) showed that N M R T, surface relaxivity is a function of surface Fe concentration. Their studies showed that surface relaxivity both reached an early maximum (trend 1) and only changed by a factor of 2 (trend 2) over the surface Fe range of 0 to 10,000 PPM. Since we have similar results for our calculated surface relaxivity data with pyrite, and we surmise that our sand also contains surface iron. For instance, in figure 4, surface relaxivity is shown to reach a maximum value after 1% added pyrite (trend 1). Also in figure 4, surface relaxivity changes by only a factor of 2 over the 0 to 5% added pyrite range (trend 2). I can therefore conclude from the similar surface relaxivity trends between my data and the data from Foley et al. (1996), who studied silicates with surface Fe, that my sample's T, p values are being dictated by surface adsorbed Fe 3 +. The principles of negative surface charge attracting and adsorbing positive metal ions can be applied to our oil-wet sand and pyrite T, results. Consider the formation of the oil-wet layer on the surface of the sand. The positive members of the oil layer will preferentially associate with the negative charge on the surface of the sand. The oil-water interface should therefore appear to have a negative surface charge. The negative surface charge at the water-oil interface is a likely adsorption area for the positively charged Fe 3 + from the pyrite oxidation. Assuming the Fe 3 + is adsorbing at the oil-water interface, Fe 3 + can act as a site of enhanced relaxation. The adsorbed Fe 3 + cation's increased strength in surface relaxation is overriding the weak surface relaxation from the oil layer alone. The decrease in N M R T, can be assumed to be from the adsorption of Fe 3 + at the oil-water interface. Arguably, the decrease in T, of the pore water in the oil-wet sand packs could be explained another way. Were the oil layer on the sand to return to a water-wet state, the sand surface would 15 provide the required enhanced surface relaxivity to reduce N M R T,. But many researchers have evidence to suggest that this is not true. Cooke et al. (1974), Jennings (1958), Hancock (1955), and Michaels (1963) have all shown that metal ions in the water system promote oil-wetness of the rock surface. Johnson and Dettre (1969) even show that ferric iron (Fe3 + ) in solution will increase oil-wetness. The metal ions are believed to either become the intermediary bridge between the rock surface and the surface-active oil members or reduce the oil surfactant solubility in the pore fluid. We therefore do not believe that, in the presence of Fe 3 +, a wettability reversal from oil- to water-wet can be used to explain the decrease in N M R T, of oil-wet sands as pyrite is added. In conclusion, I believe Fe 3 + is being adsorbed to both the water- and oil-wet surfaces of the sand. This adsorbed paramagnetic (Fe3 + ) is becoming a site of enhanced relaxation for the unrelaxed water protons. No anomalous trends in the calculated surface relaxivities were found. Al l trends in surface relaxivity have been found in other similar N M R T t studies. Surface relaxivity has been shown to reach a maximum value after only 1% pyrite was added to the water-wet sand. Also, the surface relaxivity only increased by a factor of 2 over the entire 0 to 5% range of added pyrite. Overall, surface relaxivity is relatively constant over the same range of pyrite. 5. Conclusions N M R T, values for both oil- and water-wet sand packs that are saturated with water are dependent on the amount of added pyrite. I believe that the oxidation product of pyrite, Fe3*, is responsible for relaxation time decreases in both types of sand wettability. Fe 3 + is not only reducing the N M R T, rock relaxation time by decreasing the bulk water solution relaxation time but is also most likely reducing N M R T, by adsorbing to the water- and oil-wet surfaces of the sands by the following scenario. The adsorbed Fe 3 + is becoming a site of enhanced relaxation that has greater relaxation strength than either the water- or oil-wet surfaces alone. Foley et al.'s (1996) specific study on the effect of surface Fe in synthetic silicates on surface relaxivity showed that surface relaxivity reaches a maximum at low amounts of surface Fe 16 and changed only by a factor of 2 over the wide range of surface Fe. M y T, results from the water-wet sand packs show the same two trends for my calculated surface relaxivities as a function of added pyrite. F e 3 + from the oxidation of pyrite is most likely becoming adsorbed to the water-wet surface and enhancing the relaxation strength of the water-wet surface. 17 Investigations of T, relaxation mechanisms on oil- and water-wet sand packs saturated with acidic, alkaline, and saline water 7. Introduction The first part of this thesis titled "Investigations of T, relaxation mechanisms on water-saturated oil- and water-wet sand packs mixed with pyrite" gives a detailed description of N M R in rocks filled with a hydrogen-based fluid. In summary, rock interstices are usually filled with water or oil. Once the fluid-filled rock is placed in a magnetic field (H0), the protons in the fluid will align in the direction of H 0 . N M R T, relaxation techniques are based on moving the aligned protons from H 0 and observing how long it takes for them to return to their original aligned state. The relaxation time T, of a proton-based fluid in the pore space of a rock is given by the following equation (Straley et al., 1995) T,= [p * (S/V) + l /T . J - 1 (1), where p is the surface relaxivity of the pore wall, S/V is the surface-to-volume ratio of the pore space, and T l b is the relaxation time of the pore fluid in bulk. This equation has two components: a surface relaxation component, represented by p * (S/V), and a bulk relaxation component, T l b . As a consequence, the physical and chemical state of the pore surface is a critical parameter in determining T, of pore fluid in a rock. Of particular interest in this thesis is the role of wettability of the solid, and the effect of the pH and salinity of the adjacent pore fluid. Wettability is defined as the tendency of one fluid to spread or adhere to a solid surface in the presence of other immiscible liquids. N M R relaxation studies that have focused on different types of wettability have shown contradictory results. Most oil-wet rocks and sands, fully 18 saturated with water, exhibit relatively long relaxation times that are close to bulk solution relaxation times (Kanters, 1996). Williams and Fung (1982) and Hsu (1994) have shown that organosilane-treated sands, also fully saturated with water, have shorter relaxation times characteristic of water-wet sands. This result is puzzling and has shown that little is actually known about N M R surface relaxation mechanisms. The behavior of the pore surface is affected by the pH of the pore fluid. The surface properties of the quartz adjacent to water are very dependent upon the pH of the water, as shown in figure 1. At pH below 2, the quartz surface adsorbs hydrogen (Parks, 1984), and becomes positively charged at this very low pH. Once the pH increases past 2, the number of positive sites created by the adsorbed hydrogen equals the number of negative quartz surface sites. This is called the isoelectric point, and it represents the point at which the quartz surface is neutral. Increasing the pH past 2 increases the negative surface charge on the quartz. The charge on oil-wet surfaces also exhibits a dependence on pH. Crude oil surfaces have been shown to be positively charged at low water pH values and negatively charged at high values (Dubey and Doe, 1993; Buckley, 1994). Oils contain surface-active components such as carboxylic acids and bases (amines) which are sensitive to changes in the pH of the adjacent pore water (Fig. 2). The oil-water interface is positively charged when the adjacent pore water is low in pH. The oil surface becomes negatively charged when the pH of the water is raised. The positive charge is from the protonation of the amines in the oil and the negative charge is from the deprotonation of the carboxylic acid (Buckley, 1994; Dubey and Doe, 1993). Crude oils also have a point at which pH of the adjacent water renders the oil-water interface neutral; the isoelectric point of the oil. Changing the pH of the pore fluid can therefore be expected to change the surface of quartz and crude oil. Kanters (1996) measured N M R T, on oil- and water- wet sand packs filled with acidic water. His results showed that both water- and oil-wet sand T, gradually increased as the pH of the water increased from 2 to 7. This thesis is an extension of Kanters' research in which I record 19 0 net surface charge is posit ive © . H H \ H H \ f \ negative , posit ive s i te neutral s j t e s i te pore water pore water pH less than 2 surface of quartz at RZC (pH of adjacent water is about 2): net surface charge is zero/ neutr al ©+ O = o pore water pH about 2 S i ,o o net surface charge is negative 0 pore water pH greater than 2 Figure 1. Schematic of quartz surface charge as a function of pore water pH: A) positive surface charge at pH below 2; B) point-of-zero surface charge at pH around 2; C) negative surface charge at pH above 2. 20 A c i d i c w a t e r C a r b o x y l i c A c i d Oil ,0 OH W a t e r S u r f a c e - a c t i v e ^ i o n i z a b l e O o u p s OH O H A m i n e N. OH Figure 2. Schematic of oil surface charge as a function of water pH: A ) surface-active groups fully protonated with acidic water; B & C) less acidic water deprotonates the lower pKa-valued amine rendering it neutral, carboxylic acid stays protonated and positively charged; D & E) carboxylic acids deprotonate with slightly more basic water, surface charge changes to negative. 21 the N M R T, response in water- and oil-wet sands when the water pH is greater than 7. I also measured T, as a function of salinity. 8. Experimental Procedure Ottawa sand between 120 and 140 U.S. mesh size (115 um mean grain diameter) was used in the T, relaxation experiments. This sand was used for four reasons. The first reason is related to Table 1, a copy of a specification sheet from the Ottawa sand distributor, Wedron Inc. In addition to the 99.9% S i 0 2 found in the Ottawa sand, we also see that there are trace amounts of other minerals. Since the sand is primarily Si0 2 , any experiments done on glass and other quartz rocks easily can be related to the Ottawa sand I used. Also, I believe, based on the chemical analysis in table 1, that there is a distinct possibility of calcite being present in or on the sand. Although most geologic convention states the Ca concentration in terms of calcium oxide (CaO), this mineral form is not expected in the geologic environment for the Ottawa sand; since the sand is mature and any other Ca-bearing minerals such as epidote or Ca-feldspars are not expected to be present in such a mature sand. It is therefore assumed that the CaO present in the sand analysis is most likely calcite (CaC0 3). Second, the unimodal grains of sand are highly spherical. This will allow me to assume a simple grain-packing geometry. Thirdly, as Tan (1993) states, S i0 2 (quartz) is relatively insoluble in all waters at the times scales used in these experiments. This ensures that our sand surfaces are not physically changing during any of our experiments. Insolubility of the sand allows me to compare samples without worrying about any S/V changes from sample to sample. The fourth reason I used Ottawa sand for these experiments was because of the low Fe,0 3 content. I understood that paramagnetic ions in a pore could affect relaxation time (Korringa et al., 1962, Kenyon and Kolleeny, 1995; Foley et al., 1996). The low initial Fe 2 0 3 content reduced the possibility of contamination by paramagnetic ions. Since the paramagnetic ions in a rock's pore system affect relaxation time, I cleaned the sand with an additional step; sand was filtered through a Frantz Isodynamic Separator. The Frantz separator is primarily composed of a large, adjustable magnet. The magnet was turned on to 22 Table 1. Typical chemical analysis of Ottawa sand as copied from the sand's distributor U.S. Silica (percent reported as oxide). Si0 2 Fe 20 3 A1203 Ti0 2 CaO MgO Loss-on-ignition 99.752 0.032 0.060 0.036 <0.01 <0.01 0.10 23 magnetize both ferromagnetic and moderately paramagnetic sand grains in the Ottawa sand. As the ferromagnetic and paramagnetic sand grains passed through the separator, they were deflected out and away from the diamagnetic sand. Some of the types of grains of sand that were extracted from the sand were tourmaline, illmenite, pyrite- and ferric oxide-coated quartz; identified by energy dispersive spectrometry. Appendix E shows photomicrographs of some of these minerals. The resulting cleaned sand is believed to be dominantly quartz, based macroscopically on the light white-beige color, conchoidal fracture patterns on the surfaces of the grains, and energy dispersive spectrometry of the sand. Back-scattered electron radiation images were produced of the separated sand to estimate the amount of possible trace minerals present. The greatest amount of trace minerals found in the sand was 0.07%. Both Semple (1990) and Khulbe (1996) describe Cold Lake crude, the oil used in this study, as a viscous asphaltene-rich oil. Most of the surface-active groups and paramagnetic materials are associated with the neutral and/or the acidic fractions of the oil (Khulbe, 1996; Semple , 1990). Cold Lake crude was used to coat separated, Ottawa sand to create oil-wet sand grains. Naturally water-wet sand must be modified to become an oil-wet sand. I first prepared the sand for optimum oil wetting by silanizing the surface with octadecyltrichlorosilane (C 1 8SiCl 3). The silanization process involves first dissolving C l g SiC l 3 i n toluene which is then mixed with 15 g of sand and refluxed in a round-bottomed reflux apparatus for 48 hours. The sand is then drained of the organic solution, washed with four 100-mL aliquots of toluene, drained of the washing toluene, and left in a fumehood until the residual solvent completely evaporates. Silane covalently bonds to the surface of the quartz, leaving the organic hydrocarbon tails projecting into the pore (Fig. 3). The silanization creates hydrophobic surfaces on the sand. Hydrophobicity is confirmed by two tests; 1) water beads when placed on a thin layer of silanated sand, and 2) the silanated sand floats at the water-heptane interface when placed in a water-heptane mixture and shaken. Consequently, the sand is considered silanated and ready for the oil-wetting procedure. 24 quartz surface H S i S i of \ ( q u a r t z ) / o o H © octadecy l t r ichlorosi lane approaches quartz surface H H H © Cl Cl \ / S i ^18 oct adecyIt r ichlorosi lane B quartz surface Silane bonds to quartz surface, as chlorine atom kicks off silane and hydrogen kicks off quartz surface to form HCI by-product Figure 3. Schematic showing the silanization process: A) octadecyltrichlorosilane approaches quartz surface; B ) silane attaches to surface. 25 Asphaltenes are long-chain, high-molecular-weight hydrocarbons that are responsible for wetting rocks with oil (de Pedroza, 1993). By using a long carbon-chained silane (C l 8 SiCl 3 ) , the oil-wetting asphaltenes of the Cold Lake crude should associate with and adsorb to the prepared silanated surface (Fig. 4). The oil wetting procedure begins by dissolving 5 g of crude oil in 100 mL of 50:50 heptane:toluene solution. The silanized sand is mixed with the dissolved oil and allowed to sit. After approximately 12 hours the organic solvent mixture has evaporated leaving behind a tar and sand mixture. The tar is washed from the sand using a heptane-toluene solvent. The sand is filtered again using the oil-saturated heptane/toluene solution mixed with ethanol. The sand now is a chocolate-brown color, indicating the presence of an oil layer on the quartz sand surfaces. Solutions of varying pH and salinity were created to use as pore fluids in our sand packs. These solutions are presented in Table 2. A l l chemicals used were reagent grade; pH was controlled using HCI and NaOH. Each of the 18 water solutions were degassed and measured for bulk solution relaxation times. These 18 solutions were also degassed prior to saturating 100% water-wet and 100% oil-wet sand packs. The sand was packed into a Teflon™ holder and evacuated to 60 mm of Hg. Evacuated sand packs were then saturated with water. The T, values of both the bulk solutions and the sand packs were measured within 48 hours of degassing. To check for interaction between sand packs and solutions, additional experiments were conducted on extracted pore fluids. Solutions of 0.01 M NaCl at pH values of 1.85, 3, 5, 7, 9, and 11 were mixed with both oil- or water- wet sand in a syringe. The water was extracted after 48 hours and measured for T, relaxation times. These experiments were conducted in order to determine whether there were any changes in the relaxation time of the pore water. Unfortunately we were unable to check for any change in pH due to the small volume of fluid. It is important to note that all pH values referred to are those measured on the solution before saturating the samples. In future experiments the pH of the fluid should be measured after equilibration with the solid. 26 quartz surface Figure 4. Schematic of the oil-wet layer formation with a silanated quartz surface 27 Table 2. List of the different types of pore fluid as a function of pH and salinity used in our study. 1.85 3 5 7 9 11 0.01 M water 1 water 2 water 3 water 4 water 5 water 6 NaCl 0.1 M water 7 water 8 water 9 water 10 water 11 water 12 1.0 M water 13 water 14 water 15 water 16 water 17 water 18 28 T, relaxation times for the bulk solutions and sand packs filled with water were determined using a pulsed proton N M R spectrometer. The components of the spectrometer are a Bruker iron-core electromagnet with an SXP™ probe with 10 JLLS of deadtime. The 2.12 Tesla electromagnet (90 MHz precessional frequency for protons), operating at or just above room temperature (-22° C), is run by a computer program that controls the radio frequency transmitter. Water loss from the samples was considered because the experimental temperature ranged from room temperature to slightly above room temperature. After measuring the amplitude of the net magnetization both before and after the sample run, and noticing negligible differences in the net magnetization, water loss was not considered to be present in our experiments. In N M R relaxation studies, M is rotated by H p a radio frequency electromagnetic field using a sample coil. The length of time electricity is switched on to create H, is referred to as the pulse length. Rotating M 90° and 180° in these experiments, needed for a T, relaxation time inversion-recovery collection, required 2.2 and 4.4 JU.S pulse lengths, respectively. The decay of net magnetization in our sand packs was collected using a modified inversion-recovery pulse sequence that is represented by the following: 90° and 180° - x - 90°. Part one, or 90°, is a measure of M in the -i-y'-direction after M is allowed to achieve equilibrium with the H 0 or -i-z'-direction. The 90° signifies the rotation angle M from the -i-z'-direction to the -i-y'-direction. Part two, or 180° - x - 90°, is slightly more complicated than part one. The second 29 part of the pulse sequence is performed with 15 separate x values. Each pulse sequence with each x is as follows: M is initially in the equilibrium state before being rotated to the -z'-direction (180°), then time x is waited before the remaining M is rotated to the y'-direction (90°) where M is measured. Each of the 15 M values from part two is then subtracted from the M of part one to obtain a net magnetization decay curve that represents the sand pack's relaxation of the pore fluid. Inversion is possible if we treat N M R in rocks as a collection of pores that relax independently of each other. Therefore each pore size is represented by a single T, relaxation time. Pores in rocks can range in size from microporosity to large vugs. Accordingly, relaxation times for micropores and large vugs are on the order of 1 to 10 ms and 100's of ms, respectively (Kenyon, 1992). One ms and 10 s were used as limit boundaries for T, when setting up the inversion of: where M(x) is the collected data, P; are the amplitudes associated with T n , x is the time between the 180° and 90° pulses in the above inversion recovery pulse sequence, and T u ranges from 1 ms to 10 s at 160 evenly spaced values. P ; is proportional to the amount of water with T, time T u . Equation 2 is inverted for Pj. Equation 2 was solved by the nonnegative least squares methods outlined in Whittall and MacKay (1989). The recovered T H and P ; values were amplitude weight-averaged for a logarithmic mean T, (Fordham et al., 1995), according to the following equation M(x) = Z. * exp(-x / T J ] (2) Logarithmic mean T, = exp { Z; [Pt * log e(Tu)] / Pj } (3). 30 9. Experimental Results Table 3 shows the bulk solution relaxation times for the solutions described in Table 2. The T, values for these bulk solutions were relatively constant at about 3 seconds despite changes in pH and/or salinity. Shown in figure 5 is a plot of T, for water-wet sand versus the pH of the pore water used to saturate the sand. Open squares represent 0.01 M NaCl. Open triangles and open circles represent 0.1 and 1.0 M NaCl, respectively. Relaxation time did not change significantly with changes in pore fluid salinity. However, low pH water did affect the relaxation time in the water-wet sand. T, decreased by 45% (from about 1.1 to 0.6 s) in water-wet sand packs when the pore water pH lowered from 3 to 1.85. T, values for the water-wet sand packs with pore water pH values at and above 3 remained unchanged at approximately 1.1s. Shown in figure 6 are the results of T, measurements on bulk solutions that had been extracted after equilibration with water-wet sand for 48 h. Shown are the data for a solution of 0.01 M NaCl with variable pH. T, for the bulk solutions from the water-wet sand show a similar trend as the water-wet sand T, values presented in figure 5: T, values for solutions of pH 3 and higher were constant at 3 s, while T, decreased to 2 s when the pH was less than 3. A subsequent chemical analysis of the pore water at pH 1.85 after mixing with water-wet sand for 48 hours showed that the dissolved iron content increased to 1.0 mg/L from <0.03 mg/L (Fig. 7). Only trace amounts of iron (<0.03 mg/L) were present in similar pore waters with higher pH values. The T, values for the oil-wet sand are shown in figure 8. Symbols representing each salinity are the same as in figure 5, but are now filled instead of open. T, was constant at about 2.5 s at higher pH values. Starting at pH 5, however, T, values decreased with decreasing pH. Ultimately, T, decreased to 1.5 s at pH 1.85. Relaxation time does not change with changes in pore fluid salinity. 31 Table 3. T i values (in seconds) for pore fluids before sand pack saturation as a function of pH and salinity. PH salinity 1.85 3 5 7 9 11 0.01 M 3.1 2.8 3.2 3.1 2.9 3.0 0.1 M 3.2 3.0 3.2 3.1 2.8 3.1 1.0 M 2.9 3.0 3.1 3.1 3.1 2.9 32 Figure 5. T, relaxation times of water-wet sand packs saturated with fluids of varying p H and salinity. 33 Figure 6. Tj values for pore fluids from water-wet sands as a function of pH. 34 3 2.5 0* C 1.5 fa 1 I 0.5 X +x- -X- X 6 pH —x-10 Figure 7. Dissolved iron in pore fluid from water-wet sands as a function of pH. 35 Figure 8. T , relaxation times of oil-wet sand packs saturated with fluids of varying p H and salinity. 36 Three points were repeated in Figure 8. These points, at pore water pH 1.85, 7, and 11 and salinity concentration of 0.01 M NaCl, were repeated to see if oil-wet preparations in the beginning and end of the overall experiments produced roughly similar T, values. I did this because I questioned the qualitative nature of the filtration step in the oil-wetting procedure. Although the starting ingredients for oil-wetting were fixed, the question about oil-wetting arose after creating multiple batches of oil-wet sand. Once the residual oil was removed from the sand/oil mixture by way of the heptane-toluene-ethanol mixture, the color of the sand was visually assessed. If the sand color was not dark brown, the sand was refiltrated with the mixture until the dark brown color on the surface of the sand was visually the same as earlier oil-wet sand batches. This refiltration step was sometimes repeated and sometimes not when making oil-wet sand, depending on the dark browness of the oil-wet sand. Therefore, I wanted to test the response of T, with differently prepared oil-wet sand packs, each preparation of oil-wet sand having different numbers of filtration steps. The similar T, values for these repeat points for the oil-wet sands proved to me that the oil-wetting procedure is robust and reproducible. Shown in figure 9 are the results of T, measurements on bulk solutions that had been extracted after equilibration with oil-wet sand for 48 h. The data for a solution of 0.01 M NaCl with variable pH are shown. Measurements of T, for the bulk solutions from the oil-wet sand showed a similar trend to that of the oil-wet sand T, values presented in figure 8: T, values for solutions of pH 5 and higher were constant (~3 s), while T, decreased to 2.2 s once the solutions dropped to pH 1.85. An in-depth view of the data from figures 5, 6, 8, and 9 are presented in appendices C and D. Error estimates of T, are difficult to obtain for individual sand packs because only one T, was measured for most of the samples. However, based on 15 T, measurements of a clean sand saturated with distilled degassed water (pH about 5.1), estimated errors are +/- 0.1 s. 37 Figure 9. T , values for pore fluids from oil-wet sands as a function of pH. 38 10. Discussion 10.1 Water-wet sands The results of the experimental measurements show that relaxation of pore water protons by water-wet sand is pH dependent. As described in equation 1, rock relaxation is composed of both a surface and bulk solution relaxation component, represented by the p (S/V) and T l b terms, respectively. First, the bulk solution component is discussed. Figure 6 shows the bulk solution T, values as a function of pH for the pore fluid from the water-wet sand packs. T, is 3 s for every bulk solution except at pH 1.85, where T, drops to 2 s. The bulk solution relaxation is enhanced at pH 1.85. It is possible that the surface properties of the water-wet Ottawa sand at such low pH values can help understand what is contributing to the decrease in T, of the bulk solutions. First, it is very unlikely that the water-wet sand was completely cleaned of all minerals and mineral surfaces that could contain metal atoms or adsorbed paramagnetic metal ions. Energy dispersive spectrometry showed that even separated Ottawa sand has small amounts of surface minerals that are iron-rich (Appendix E). An analysis of the pore water at pH 1.85 after mixing with water-wet sand showed that the dissolved iron content increased to 1.0 mg/L from <0.03 mg/L (Fig. 7). Only trace amounts of iron (<0.03 mg/L) were present in similar pore waters with higher pH values. At low pH values, metals such as Fe are leachable from the minerals and mineral surfaces that were not excluded during the magentic separation process of the sand (Klein and Hurlbut, 1985). These metal-containing minerals or mineral surfaces could contribute metal ions to the pore water, increasing the paramagnetic concentration of the water. The increase of paramagnetic ions to the bulk water solutions at low pH would consequently lower T,, as described in the introduction on bulk solution relaxation. Moreover, given the positive surface charge of the quartz at low pH values, any positive ions such as Fe 3 + going into solution will remain in solution. It is highly unlikely that they will adsorb to a surface with a net positive charge. 39 To use equation 1 for an accurate calculation of surface relaxivity, I must first relate the surface to volume ratio of the grains to the pore surface-to-volume, as done in Kanters (1996). His basic premise lies in relating the surface area and volume of the grains to the surface area and volume of the pore space. First, the surface area of the grains is essentially equal to that of the pore space. Second, the volume of the pore space is equal to the total volume less the grain volume. Dividing the total volume less the grain volume term and the pore space volume term by the total volume relates both of these values to porosity. The Kanters' reconfiguration sets the S/V of the pore space equal to 6( 1 -<b)/<j>*d where (j) is the porosity of the sand pack and d is the diameter of the unimodal sand grains. T l b as a function of pH is obtained from figures 6 and 9. Figures 10 and 11 present the calculated surface relaxivity as a function of pH for the oil- and water-wet sand packs, respectively. Figure 10 shows that p varied from 6 to 14 um/s for water-wet sand packs. This is in good agreement with reported values of p from T, in the literature. For example, Foley et al. (1996) varied surface iron concentration and p ranged from 3 to 12 pm/s. Also, Kenyon et al. (1989) calculated p at about 10 pm/s for scores of sandstones. Low pH pore water affects the surface relaxation properties of water-wet sands. The greatest change in water-wet T, values occurs when the pH of the pore water is less than 3 (Fig. 5). Calculated p doubles from about 6 to 14 pm/s (Fig. 10) when pH of the pore water decreases from 3 to 1.85. We believe this decrease in T,, and increase in p, as pH decreases is related to the change in surface charge of the quartz. Quartz is positively charged when pH is less than 2 (Parks, 1984). The overpopulation of hydrogen on the surface at the low pH (Fig. la) must create an environment more conducive to proton relaxation. 40 Figure 10. Calculated surface relaxivities for water-wet sands as a function of pore water pH. 41 fl 0.5 6 p H 10 12 Figure 11. Calculated surface relaxivities for oil-wet sands as a function of pore water p H . 42 10.2 Oil-wet sands N M R relaxation of pore water protons in oil-wet sands also has a surface and a bulk solution relaxation component. First, let's look at the bulk solution relaxation mechanisms for the oil-wet sand. Figure 9 shows that T l b decreased from 3 s at pH values 5 and above to 2.7 and 2.3 s at pH 3 and 1.85, respectively. This T l b decrease at the lower pH values of pore water leads me to think that paramagnetic ions must be present to reduce the relaxation time of the bulk solutions. However, in this case I believe the paramagnetic ions are coming from the oil layer on the sand surface instead of the sand surface. As described earlier, Cold Lake crude has a high concentration of both V 0 2 + and organic free radicals that are associated with the acidic fraction of the asphaltenes of the crude. Both of these oil constituents are paramagnetic. When acidic pore water comes in contact with the acidic oil fraction, the paramagnetic V 0 2 + and radicals should become water soluble and transfer from the oil to the pore water. It is very likely that dissolved V 0 2 + and organic free radicals in pore water are reducing the T l b in the oil-wet sands. Oil-wet sand surface relaxivities, calculated using the same procedure as used for the water-wet sands, are presented in figure 11. As with water-wet sands, p is also relatively constant at the higher pH values of pore water. From pH 5 to 11, the average for p is 1 um/s. Once the pH drops from 5 to 3, p increases to 2.25 um/s. p remains at about 2.25 um/s as pH drops from 3 to 1.85. The surface relaxivity results show a definite pattern in the oil-wet sand packs: when the water pH is above 5, p is small, and when the water pH is below 5, p is high. To be consistent with these experimental observations, I suggest that the physical characteristics for the oil-water interface during the pH changes are important. As discussed earlier, Buckley (1994) and Dubey and Doe (1993) state that the oil surface is positively charged at low pH values and negatively charged at higher values. This surface charging is believed to be directly related to the ionization of 43 the surface-active carboxylic acids and basic components, such as amines, in the crude oil. Buckley (1994) presents a table of acids and bases that are believed to be surface-active (Table 4). The most striking trend that this table shows is the commonality of the ionization constants for both the acids and bases. Notice that four of five bases and three of four acids have ionization constants between 3 and about 5. Similarly, p changes for the oil-wet sands between pH 3 and 5; leading us to believe that ionization of the acids and/or bases could affect surface relaxation properities. Although a much more detailed analysis of our crude oil surface is needed to make any definite conclusions, I propose that the surface-active bases and acids could have a direct effect on the relaxivity of the crude oil surface. The low pH of the pore water must create sites of enhanced surface relaxation on the oil-water interface. However, the mechanism by which this takes place is not understood. 11. Conclusions In this work are presented the results of T, measurements on oil- and water-wet sands as a function of pore fluid chemistry. This work has shown that surface and bulk solution chemistry is an important factor to consider when interpreting relaxation data from oil- and water-wet pore surfaces. Although pH of the pore fluid proves to be an important consideration when dealing with N M R T p salinity is not a factor. In water-wet systems, as pH decreases below 3, the measured T, decreases. This decrease can be attributed to two relaxation mechanisms which are activated by low pH pore fluids: a positive surface charge on the quartz grains and an increased aqueous paramagnetic ions content due to increased solubility of unseparated minerals on the surfaces of the sand. From the relatively constant T, throughout the pH range 3-11, negative surface charge on the sand surfaces appears not to affect T s surface relaxation mechanisms. However, it is important to note that the pH of the pore fluid, in equlibrium with the solid, was not measured. It is possible that the buffering action 44 Table 4. List of dissociation constants for acids and bases that are believed to represent the acidic and basic characteristics of crude oil (Buckley, 1994). Compound P K a Acids: acetic acid 4.75 n-nonanic acid 4.96 benzoic acid 4.20 naphthenic acid a) 3.70 P) 4.17 phenol 9.89 Bases: laurel amine 10.63 an i l ine 4.63 pyr id ine 5.25 quinol ine 4.90 4 5 of trace calcium carbonate in the sand caused all the solutions with initial pH values greater than 3 to reach the same high pH value in the pore space. This issue requires further study. Relaxation mechanisms of pore water for oil-wet sands appear to be quite different than those for water-wet sands. Acidic-related V 0 2 + and organic free radicals in the oil layer may become soluble in pore water at low pH. These constituents, with their unpaired electrons, act like dissolved paramagnetic ions and decrease T l b relaxation time. For the surface relaxation component, I also propose that a positively or neutrally charged water-oil interface decreases T,. 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M . , 1982, The Determination of Wettability by Hydrocarbons of Small Particles by Deuteron Tip Measurement: Journal of Magnetic Resonance, 50, 71-80. 48 APPENDIX A This appendix gives the sample numbers and reference page numbers for figures 1, 2 and 3a from the first part of the text titled: "Investigations of T l relaxation mechanisms on water-saturated oil- and water-wet sand packs mixed with pyrite" 49 Sample numbers for oil-wet sand and variable added pyrite saturated with water. 1 2 3 percent pyrite added sample number Tl(sec) 0 46 1.7 Percent pyrite 2 45 1.0 added 5 44 0.8 Page number in appendix B for specific Tj data. sample number 0 B -2 Percent added pyrite 2 B -3 5 B -4 50 Sample numbers for water-wet sand and variable added pyrite saturated with water. 2 3 percent added pyrite sample number Tl(sec) Percent pyrite added 0 0 0.5 1 1.5 2 3 4 5 51 53 52 54 55 57 58 59 60 0.68 0.68 0.55 0.40 0.44 0.42 0.38 0.36 0.38 Page number in appendix B for specific T l data. page number 0 B-5 0 B-6 0.5 B-7 1 B-8 Percent added pyrite 1.5 B-9 2 B-10 3 B - l l 4 B-12 5 B-13 51 Sample numbers for pore water from water-wet sand and variable added pyrite. j : 1 1 1 1 2 3 4 5 percent pyrite added sample number Tl(sec) 0 86 3.1 Percent pyrite added 5 49 1.7 Page number in appendix B for specific T l data. sample number 0 B-14 Percent added pyrite 5 B-15 3.50E+03 T • 3.00E+03 -2.50E+03 -2.00E+03 -H 1.50E+03 -1.00E+03 -5.00E+02 0.00E+00 -0 52 APPENDIX B This appendix gives T, and amplitude results for sample numbers listed in appendix A from the first part of the text titled: "Investigations of T, relaxation mechanisms on water-saturated oil- and water-wet sand packs mixed with pyrite" 53 Series 46 - oil-wet sand with 0% pyrite added saturated with distilled de-aired water. 8.00E+02 T 7.00E+02 -« 6.00E+02 -3 £ 5.00E+02 -a. E < 4.00E+02 -a> •2 3.00E+02 J-J5 "a! « 2.00E+02 j 1.00E+02 --0.00E+00 I 1 M 1 1 1 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) 1.8 752 98.9 T l (s) Amplitude Percent 1.2e-l 8.0 1.1 (1/T1) ave 6.5e-l T l ave 1.8 T l lgmn 1.7 54 Series 45 - oil-wet sand with 2% pyrite added saturated with distilled de-aired water. 8.00E+02 j 7.00E+02 -« 6.00E+02 T 3 5 5.00E+02 -I-tx B < 4.00E+02 + •2 3.00E+02 a w 2.00E+02 1.00E+02 --0.00E+00 J 1—• " >—i J » 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) 1.1 738 99.5 T l (s) Amplitude Percent 3.2e-2 3.4 0.5 (1/T1) ave 1.1 T l ave 1.1 T l lgmn 1.0 55 Series 44 - oil-wet sand with 5% pyrite added saturated with distilled de-aired water. 8.00E+02 7.00E+02 « 6.00E+02 3 1.00E+01 T l (s) Amplitude Percent 2.6e-l 46.3 6.1 (1/TI) ave 1.4 8.1e-l 713 93.9 T l ave 7.8e-l T l lgmn 7.6e-l 56 Series 51 - acid-washed water-wet sand with 0% pyrite added saturated with distilled de-aired water. 5.00E+02 T 4.50E+02 --4.00E+02 -3.50E+02 3.00E+02 -2.50E+02 -2.00E+02 -1.50E+02 -1.00E+02 -5.00E+01 -0.OOE+00 1 * 1 i : 1 1.00E-03 1.00E-02 1.00E-01 1 .OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.5e-3 2.8 0.5 (1/TI) ave 3.8 5.4e-2 10.2 1.9 T l ave 5.0e-l 42.5 7.9 7.0e-l 7.4e-l 484 89.7 T l lgmn 6.8e-l 57 cu 3 a. S < Series 53 - acid-washed water-wet sand with 0% pyrite added saturated with distilled de-aired water. T l (s) 3.6e-3 2.4e-2 2.5e-l 7.8e-l Amplitude 7.3 2.4 17.5 453 Percent 1.5 0.5 3.6 94.3 (1/T1) ave 5.8 T l ave 7.5e-l T l lgmn 6.8e-l 58 Series 52 - acid-washed water-wet sand with 0.5% pyrite added saturated with distilled de-aired water. 5.00E+02 4.50E+02 4.00E+02 "5 3.50E+02 "H. 3.00E+02 a < 2.50E+02 | > 2.00E+02 "3 1.50E+02 ai 1.00E+02 5.00E+01 0.00E+00 1.00E-03 1.00E-02 1.00E-01 T l (s) 1.OOE+00 .00E+01 T l (s) 1.8e-3 1.7e-l 7.5e-l Amplitude 19.7 30.6 476 Percent 3.7 5.8 90.4 (1/TI) ave 22.5 T l ave 6.9e-l T l lgmn 5.5e-l 59 Series 54 - acid-washed water-wet sand with 1% pyrite added saturated with distilled de-aired water. 6.00E+02 5.00E+02 T3 2 4.00E+02 "5. S < 3.00E+02 CU > « 2.00E+02 CU 1.00E+02 O.OOE+00 4 l.OOE-03 JL 1.00E-02 l.OOE-01 T l (s) l.OOE+00 .OOE+01 T l (s) 2.3e-3 l.Oe-1 4.5e-l Amplitude 10.0 15.3 560 Percent 1.7 2.6 95.7 (1/T1) ave 10.0 T l ave 4.4e-l T l lgmn 4.0e-l 60 Series 55 - acid-washed water-wet sand with 1.5% pyrite added saturated with distilled de-aired water. 6.00E+02 j 5.00E+02 •a 2 4.00E+02 -"5. E < 3.00E+02 --01 > 2 2.00E+02 -<L> 1.00E+02 -0.OOE+00 -I » 1 • M 1 : f 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.8e-3 10.5 1.7 (1/TI) ave 11.8 7.8e-2 9.6 1.6 T l ave 5.0e-l 591 96.7 4.9e-l T l lgmn 4.4e-l 61 Series 57 - acid-washed water-wet sand with 2% pyrite added saturated with distilled de-aired water. 6.00E+02 5.00E+02 2 4.00E+02 "a. E < 3.00E+02 | ca > 2 2.00E+02 } 1.00E+02 O.OOE+00 l.OOE-03 .00E-02 l.OOE-01 T l (s) .00E+00 l.OOE+01 T l (s) Amplitude Percent 2.8e-3 7.5 1.3 (1/T1) ave 7.2 1.6e-2 5.3 0.9 T l ave 1.4e-l 22.2 3.7 4.6e-l 4.8e-l 559 94.1 T l lgmn 4.2e-l 62 Series 58 - acid-washed water-wet sand with 3% pyrite added saturated with distilled de-aired water. 7.00E+02 T 6.00E+02 -•o 5.00E+02 -9 g 4.00E+02 -< « 3.00E+02 --a * 2.00E+02 --1.00E+02 -0.00E+00 -1 ' 1 ^ II : 1 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 4.6e-3 6.8 1.0 (1/TI) ave 4.7 1.2e-l 18.7 2.7 T l ave 4.1e-l 654 96.2 4.0e-l T l lgmn 3.8e-l 63 Series 59 - acid-washed water-wet sand with 4% pyrite added saturated with distilled de-aired water. 8.00E+02 -7.00E+02 -« 6.00E+02 -3 = 5.00E+02 -E < 4.00E+02 j CD •S 3.00E+02 -ca 0 5 2.00E+02 T 1.00E+02 -0.OOE+00 -I " 1 L II 1 > 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 3.6e-3 5.6 0.7 (1/TI) ave 4.9 8.3e-2 24.8 3.2 T l ave 3.9e-l 753 96.1 3.8e-l T l lgmn 3.6e-l 64 Series 60 - acid-washed water-wet sand with 5% pyrite added saturated with distilled de-aired water. 9.00E+02 8.00E+02 7.00E+02 | CU "O 2 6.00E+02 S 5.00E+02 } cu 4.00E+02 > 1 3.00E+02 cu Pi 2.00E+02 1.00E+02 0.00E+00 1.00E-03 .00E-02 1.00E-01 T l (s) .00E+00 .00E+01 T l (s) 1.2e-l 3.8e-l Amplitude 6.6 856 Percent 0.8 99.2 (1/T1) ave 2.7 T l ave 3.8e-l T l lgmn 3.8e-l 65 Series 86 - distilled de-aired water from acid-washed water-wet sand with 0% pyrite added. 3.50E+02 T 3.00E+02 •3 2.50E+02 -a g 2.00E+02 --< « 1.50E+02 -^ 1.00E+02 j 5.00E+01 -0.00E+00 1 1 1 1 1 1 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l ( S ) 3.0 Amplitude 1.9e-8 Percent 0 (1/T1) ave 3 .3e- l 3.1 340 100 T l ave 3.1 T l lgmn 3.1 66 Series 49 - distilled de-aired water from acid-washed water-wet sand with 5% pyrite added. 6.00E+02 5.00E+02 -a 2 4.00E+02 < 3.00E+02 _> JS 2.00E+02 OS 1.00E+02 0.OOE+00 -i 1.00E-03 1.00E-02 1.00E-01 T l (s) 1.OOE+00 1.00E+01 T l (s) 6.0e-3 2.0 2.0 Amplitude 18.1 l . l e - 9 599 Percent 2.9 0 97.1 (1/TI) ave 5.4 T l ave 1.9 T l lgmn 1.7 67 A P P E N D I X C This appendix gives the sample numbers and reference page numbers for figures 5, 6, 8 and 9 in the second part of the text titled: "Investigations of T, relaxation mechanisms on oil- and water-wet sand packs saturated with acidic, alkaline and saline water." 68 Sample numbers for bulk water. pH NaCl 1.85 3 5 7 9 11 0.01 109 141 152 103 118 134 0.1 113c 146 158 106 121 137 1.0 125 149 155 115 124 140 Relaxation times for bulk waters. pH NaCl 1.85 3 5 7 9 11 0.01 3.1 2.8 3.2 3.1 2.9 3.0 0.1 3.2 3.0 3.2 3.1 2.8 3.1 1.0 2.9 3.0 3.1 3.1 3.1 2.9 A more detailed Tj description is found in Appendix D for each bulk water sample. Page numbers in Appendix D for each sample are listed below. pH NaCl 1.85 3 5 7 9 11 0.01 D - 2 D-5 D-8 D - l l D - 1 4 D-17 0.1 D-3 D - 6 D-9 D - 1 2 D-15 D-18 1.0 D - 4 D-7 D - 1 0 D-13 D-16 D-19 69 Sample numbers for 100% water-wet sand saturated with water. 1 .4 1 .2 1 £ 0 8 f- 0.6 0.4 0.2 0 • Q A0.01 M NaCl O0.1 M NaCl • 1.0 M NaCl 6 P H 10 11 12 Relaxation times in seconds. p H 1.85 3 5 7 9 11 0.01 0.6 1.1 1.2 1.0 1.2 1.1 N a C l 0.1 0.6 1.0 1.2 1.0 1.2 1.2 1.0 0.7 1.0 1.1 1.1 1.1 1.2 Sample numbers. 1.85 3 5 7 9 11 0.01 110 145 154 104 119 135 N a C l 0.1 111 148 160 105 122 138 1.0 128 151 157 116 126 142 Page number in appendix D. 1.85 3 5 7 9 11 0.01 D-20 D-23 D-26 D-29 D-32 D-35 N a C l 0.1 D-21 D-24 D-27 D-30 D-33 D-36 1.0 D-22 D-25 D-28 D-31 D-34 D-37 70 Sample numbers for 100% water-wet sand extracted water. N a C l Relaxation times in p H seconds. 1.85 3 5 7 9 11 0.01 2.0 3.0 3.1 3.1 3.1 3.1 Sample numbers. N a C l 1.85 3 5 7 9 11 0.01 187 188 192 191 194 196 Page number in appendix D for specific Tl data. N a C l 1.85 3 5 7 9 11 0.01 D-38 D-39 D-40 D-41 D-42 D-43 71 Sample numbers for 100% oil-wet sand saturated with water. (0 3 T 2 . 5 2 1 .5 1 0 . 5 + 0 0 A 1 A 0 . 0 1 M NaCl • 0.1 M NaCl • 1 M NaCl 6 P H 1 0 1 2 Relaxation times in seconds. pH 1.85 3 5 7 9 11 0.01 1.7,1.3 1.8 2.5 2.7,2.4 2.4 2.9,2.7 NaCl 0.1 1.6 1.9 2.5 2.3 2.4 2.6 1.0 1.5 1.7 2.6 2.4 2.5 2.7 Sample numbers. 1.85 3 5 7 9 11 0.01 183, 131 144 153 184, 132 120 136, 185 NaCl 0.1 130 147 159 133 123 139 1.0 129 150 156 117 127 143 Page number in appendix D for specific Tj data. 1.85 3 5 7 9 11 0.01 D-44,45 D-48 D-51 D-54,55 D-58 D-61,62 NaCl 0.1 D-46 D-49 D-52 D-56 D-59 D-63 1.0 D-47 D-50 D-53 D-57 D-60 D-64 72 Sample numbers for 100% oil-wet sand extracted water. 3.5 3 2.5 + £ 2 i— 1.5 1 0.5 0 0.01 M NaCl 0 1 2 3 4 5 6 7 PH -I 1 1 ! 1 8 9 10 1 1 1 2 N a C l N a C l Relaxation times in seconds. pH 1.85 3 5 7 9 11 0.01 2.2 2.8 3.1 3.1 3.1 3.2 1.85 Sample 3 numbers. 5 7 9 11 0.01 186 189 193 190 195 197 Page number in appendix D for specific Tl data. N a C l 1.85 3 5 7 9 11 0.01 D-65 D-66 D-67 D-68 D-69 D-70 73 A P P E N D I X D This appendix gives T, and amplitude results for sample numbers listed in appendix C from the second part of the text titled: "Investigations of T, relaxation mechanisms on oil- and water-wet sand packs saturated with acidic, alkaline and saline water." 74 Series 109 - bulk water of pH 1.85/0.01 M NaCl. 9.00E+02 j 8.00E+02 | 7.00E+02 -•o 3 6.00E+02 •• E 5.00E+02 -OJ 4.00E+02 --> 1 3.00E+02 -W 2.00E+02 -1.00E+02 -r 0.OOE+00 -I 1 1 -— 1 1. 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) 3.1 848 100 T l (s) Amplitude Percent 3.0 1.5e-8 0 (1/TI) ave 3.3e-l T l ave 3.1 T l Igmn 3.1 75 Series 113c - bulk water of pH 1.85/0.1 M NaCl. 9.00E+02 8.00E+02 7.00E+02 3 6.00E+02 5 5.00E+02 „ 4.00E+02 > 1 3.00E+02 } * 2.00E+02 1.00E+02 0.00E+00 .00E-03 .OOE-02 1.00E-01 T l (s) 1.OOE+00 1.00E+01 3.2 875 100 T l (s) Amplitude Percent 6.8e-3 4.4e-l 0 (1/TI) ave 3.9e-l T l ave 3.2 T l lgmn 3.2 76 Series 125 bulk water of pH 1.85/1.0 M NaCl. 5.00E+02 4.50E+02 4.00E+02 | 3.50E+02 ii. 3.00E+02 E < 2.50E+02 | 2.00E+02 "3 1.50E+02 OS 1.00E+02 -f 5.00E+0: 0.OOE+00 .00E-03 .00E-02 1.00E-01 T l (s) 1.OOE+00 .00E+01 T l (s) Amplitude Percent 2.2e-2 4.8 1 (1/TI) ave 7.8e-l 3.0 5.2e-9 0 T l ave 3.1 473 99 3.0 T l lgmn 2.9 77 Series 141 - bulk water of pH 3/0.01 M NaCl. 3.00E+02 T 2.50E+02 -5 2.00E+02 --"5. E < 1.50E+02 --cu « 1.00E+02 -CU OS 5.00E+01 •• 0.00E+00 ' - i 1 1 1 * 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 8.1e-3 1.8 0.6 (1/T1) ave 1.1 2.8 3.9e-8 0 T l ave 2.9 283 99.4 2.9 T l lgmn 2.8 78 Series 146 - bulk water of p H 3/0.1 M NaCl. 4.00E+02 3.50E+02 « 3.00E+02 s = 2.50E+02 ^ 2.00E+02 cu ••S 1.50E+02 0 4 1.00E+02 5.00E+01 0.00E+00 .00E-03 .OOE-02 1.00E-01 T l (s) 1.00E+00 1.00E+01 T l (s) Amplitude Percent l . l e - 2 2.3 0.6 (1/T1) ave 8.5e-l 3.0 7.9e-9 0 T l ave 3.1 373 99.4 3.1 T l lgmn 3.0 79 Series 149 - bulk water of pH 3/1.0 M NaCl. 7.00E+02 -6.00E+02 •a 5.00E+02 •L s g 4.00E+02 --g 3.00E+02 -cs « 2.00E+02 -1.00E+02 --0.00E+00 J 1 1 1. 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.9e-2 3.7 0.7 (1/TI) ave 6.9e-l 3.0 1.3e-8 0 T l ave 3.1 512 99.3 3.1 T l lgmn 3.0 8 0 Series 152 - bulk water of pH 5/0.01 M NaCl. 7.00E+02 T 6.00E+02 + -o 5.00E+02 g 4.00E+02 < « 3.00E+02 " 2.00E+02 OS .00E+02 0.00E+00 .00E-03 1.00E-02 1.00E-01 T l (s) 1.OOE+00 .O0E+O1 T l (s) 1.3e-2 3.1 3.2 Amplitude 2.4 1.8e-9 674 Percent 0.4 0 99.6 (1/TI) ave 5.9e-l T l ave 3.2 T l lgmn 3.2 81 Series 158 - bulk water of p H 5/0.1 M NaCl. 3.50E+02 T 3.00E+02 -2.50E+02 --2.00E+02 -1.50E+02 -1.00E+02 -5.00E+01 -0.00E+00 1 1 1 1 > 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T 3 3 O. E < T l (s) Amplitude Percent 3.2 333 100 (1/T1) ave 3 .2e- l T l ave 3.2 T l lgmn 3.2 82 Series 155 - bulk water of pH 5/1.0 M NaCl. 5.00E+02 4.50E+02 4.00E+02 3.50E+02 a 3.00E+02 E 2.50E+02 | 2.00E+02 "I 1.50E+02 1.00E+02 5.00E+01 0.00E+00 1.00E-03 .00E-02 1.00E-01 T l (s) .OOE+00 1.00E+01 3.2 473 99.5 T l (s) Amplitude Percent 1.6e-2 2.3 0.5 (1/TI) ave 6.1e-l T l ave 3.1 T l lgmn 3.1 83 Series 103 - bulk water of pH 7/0.01 M NaCl. 1.00E+03 -9.00E+02 -8.00E+02 -"I 7.00E+02 --l l 6.00E+02 • E < 5.00E+02 -> 4.00E+02 -« 3.00E+02 -L OS 2.00E+02 -1.00E+02 -0.00E+00 -« • 1 ' 1 ' > 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) 3.1 946 100 T l (s) Amplitude Percent 3.0 2.2e-8 0 (1/T1) ave 3.2e-l T l ave 3.1 T l lgmn 3.1 84 Series 106 - bulk water of p H 7/0.1 M NaCl. 1.20E+03 j 1.00E+03 -CU •a 3 8.00E+02 --"a £ < 6.00E+02 -cu > « 4.00E+02 --2.00E+02 -0.00E+00 -! 1 1 1 1' 1. 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) 3.1 1030 100 T l (s) Amplitude Percent 3.0 3.0e-8 0 (1/TI) ave 3 .2e- l T l ave 3.1 T l Igmn 3.1 85 Series 115 - bulk water of pH 7/1.0 M NaCl. 4.00E+02 3.50E+02 + <-> 3.00E+02 T3 3 = 2.50E+02 < 2.00E+02 at •2 1.50E+02 a "3 0 5 1.00E+02 5.00E+01 0.00E+00 1.00E-03 1.00E-02 1.00E-01 T l (s) 1.OOE+00 1.00E+01 3.2 371 99.4 T l (s) Amplitude Percent 9.0e-3 2.3 0.6 (1/TI) ave 1 T l ave 3.1 T l lgmn 3.1 86 Series 118 - bulk water of pH 9/0.01 M NaCl. 5.00E+02 4.50E+02 4.00E+02 "f 3.50E+02 Ti 3.00E+02 | S < 2.50E+02 > 2.00E+02 "3 1.50E+02 1.00E+02 5.00E+01 I 0.00E+00 .00E-03 .00E-02 1.00E-01 T l (s) 1.00E+00 1.00E+01 3.2 463 98.5 T l (s) Amplitude Percent 1.7e-2 7.3 1.5 (1/T1) ave 1.2 T l ave 3.1 T l lgmn 2.9 8 7 Series 121 - bulk water of p H 9/0.1 M NaCl. 3.50E+02 T 3.00E+02 + cu •V 3 2.50E+02 } a 2.00E+02 T E cu > 1.50E+02 -£ 1.00E+02 --5.00E+01 -0.00E+00 » 1 1 1 1 > 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l ( S ) 5.1e-3 Amplitude 6.3 Percent 1.8 (1/T1) ave 3.9 3.2 337 98.2 T l ave 3.1 T l lgmn 2.8 88 Series 124 - bulk water of pH 9/1.0 M NaCl. 3.50E+02 j 3.00E+02 CJ •a 3 2.50E+02 j a 2.00E+02 < cu > 1.50E+02 + « 1.00E+02 5.00E+01 -0.OOE+00 1 1 • II 1 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) 3.0 Amplitude 1.2e-8 Percent 0 (1/TI) ave 3.2e-l 3.1 329 100 T l ave 3.1 T l lgmn 3.1 89 Series 134 - bulk water of pH 11/0.01 M NaCl. 3.00E+02 j 2.50E+02 -• 3 2.00E+02 --"a E < 1.50E+02 --> i l.OOE+02 -5.00E+01 -0.00E+00 -! 1 i : II 1. 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.0e-2 1.7 0.6 (1/T1) ave 6.0e-l 3.0 1.3e-8 0 T l ave 3.1 291 99.4 3.1 T l lgmn 3.0 90 Series 137 - bulk water of pH 11/0.1 M NaCl. 4.00E+02 3.50E+02 « 3.00E+02 •a ••= 2.50E+02 fi. < 2.00E+02 at •Z 1.50E+02 a 0 5 1.00E+02 5.00E+01 0.00E+00 1.00E-03 .00E-02 1.00E-01 T l (s) 1.OOE+00 .00E+01 T l (s) 1.6e-2 3.0 3.1 Amplitude 1.9 1.3e-8 394 Percent 0.5 0 99.5 (1/TI) ave 6.1e-l T l ave 3.1 T l lgmn 3.1 91 Series 140 - bulk water of pH 11/1.0 M NaCl. 4.00E+02 T 3.50E+02 -« 3.00E+02 -3 = 2.50E+02 --CU E 2.00E+02 --CU •Z 1.50E+02 --J2 cu M 1.00E+02 -5.00E+01 -0.00E+00 -i » - i 1 1 ' > 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) 3.2 367 98.7 T l (s) Amplitude Percent 7.2e-3 4.7 1.3 (1/T1) ave 2.1 T l ave 3.1 T l lgmn 2.9 9 2 Series 110 - 100% water-wet sand saturated with pore water of pH 1.85/0.01 M NaCl. series 110 3.50E+02 T 3.00E+02 -1 2.50E+02 --| 2.00E+02 T < « 1.50E+02 --- 1.00E+02T as 5.00E+01 -0.OOE+00 & 1 1 L f [ 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 \ T l (s) j i T l (s) Amplitude 1.59e-3 16.8 3.2e-2 1.15 0.8 1.8e-7 0.8 331 Percent (1/TI) ave 4.8 31.5 0.3 T l ave 0.8 0 T l lgmn 94.9 0.6 93 Series 111 - 100% water-wet sand saturated with pore water of p H 1.85/0.1 M NaCl . 4.00E+02 3.50E+02 « 3.00E+02 | •a s = 2.50E+02 2.00E+02 2 1.50E+02 a "3 K 1.00E+02 I 5.00E+01 0.00E+00 1.00E-03 -I 1.00E-02 1.00E-01 T l (s) 1.OOE+00 1.00E+01 T l (s) Amplitude Percent 3.2e-3 14.9 3.9 (1/TI) ave 13.4 7.4e- l 3.5e-9 0 T l ave 7.7e- l 370 96.1 7.4e-l T l lgmn 6.2e-l 94 Series 128 - 100% water-wet sand saturated with pore water of pH 1.85/1.0 M NaCl. 3.00E+02 T 2.50E+02 --CU 2 2.00E+02 -"n. E < 1.50E+02 --cu > « 1.00E+02-cu Pi 5.00E+01 --O.OOE+00 • 1 1 . , 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 3.2e-2 2.5 0.9 (1/T1) ave 1.7 7.0e-l 276 99.1 T l ave 6.9e-l T l lgmn 6.8e-l 95 Series 145 - 100% water-wet sand saturated with pore water of pH 3/0.01 M NaCl. 3.00E+02 2.50E+02 0> -a 5 2.00E+02 E < 1.50E+02 « 1.00E+02 eg Pi 5.00E+01 0.00E+00 .00E-03 .00E-02 1.00E-01 T l (s) .00E+00 .00E+01 T l (s) Amplitude Percent 6.9e-2 3.1 1.1 (1/T1) ave 1.1 1.0 3.8e-8 0 T l ave 1.1 274 98.9 1.1 T l lgmn 1.1 96 Series 148 - 100% water-wet sand saturated with pore water of pH 3/0.1 M NaCl. i I 3.00E+02 T 2.50E+02 --O) •a 2 2.00E+02 --"a E < 1.50E+02 -> 2 1.00E+02 -01 as 5.00E+01 -0.00E+00 -I i H Jl , \ 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.3e-3 2.0 0.7 (1/TI) ave 1.4 8.5e-2 5.3 1.8 T l ave 1.1 286 97.5 1.1 T l lgmn 1.0 97 Series 151 - 100% water-wet sand saturated with pore water of pH 3/1.0 M NaCl. 4.00E+02 -3.50E+02 --« 3.00E+02 -9 = 2.50E+02 -Cu E < 2.00E+02 -•5 1.50E+02 -ca ~Z * 1.00E+02 r 5.00E+01 -0.00E+00 1 1 • Jl 1 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.7e-2 3.4 0.9 (1/T1) ave 1.28 0.2 3.5 1.0 T l ave 1.1 355 98.1 1.1 T l lgmn 1.0 98 Series 154 - 100% water-wet sand saturated with pore water of pH 5/0.01 M NaCl. 3.50E+02 T 3.00E+02 -•S 2.50E+02 -s | 2.00E+02 -< « 1.50E+02 -CO £ 1.00E+02-05 5.00E+01 -0.00E+00 * « 1 1 Jl , 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.7e-2 3.3 1 (1/T1) ave 1.2 1.9e-l 3.7 1.1 T l ave 1.3 314 97.8 1.3 T l lgmn 1.2 99 Series 160 - 100% water-wet sand saturated with pore water of pH 5/0.1 M NaCl. 3.00E+02 2.50E+02 •a 3 2.00E+02 < 1.50E+02 « 1.00E+02 ca 5.00E+01 -f 0.00E+00 1.00E-03 .00E-02 1 . 0 0 E - 0 1 T l (s) .OOE+00 .00E+01 T l (s) 5.7e-2 1.2 1.2 Amplitude 1.2 4.2e-8 2268 Percent 0.4 0 99.6 (1/TI) ave 8.9e-l T l ave 1.2 T l lgmn 1.2 100 Series 157 - 100% water-wet sand saturated with pore water of pH 5/1.0 M NaCl. 3.00E+02 T 2.50E+02 -•a 2 2.00E+02 -"S. E < 1.50E+02 --4> > « 1.00E+02 OS 5.00E+01 -0. OOE+00 -I 1 • 1 J 1 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent l.le-2 6.4e-l 0.2 (1/TI) ave 1.2 3.4e-2 1.1 0.4 T l ave 1.1 9.4e-8 0 1.2 1.2 263 99.4 T l lgmn 1.1 101 Series 104 - 100% water-wet sand saturated with pore water of pH 7/0.01 M NaCl. •o 3 4.50E+02 T 4.00E+02 3.50E+02 3.00E+02 2.50E+02 2.00E+02 | 1.50E+02 1.00E+02 + 5.00E+0: 0.00E+00 1.00E-03 4 1.00E-02 1.00E-01 T l (s) 1.00E+00 1.00E+01 T l (s) Amplitude Percent 3.0e-3 14.3 3.3 (1/T1) ave 14.8 1.5e-l 2.1 0.5 T l ave 1.3 411 96.2 1.2 T l lgmn 1.0 102 Series 105 - 100% water-wet sand saturated with pore water of p H 7/0.1 M NaCl. 4.00E+02 T 3.50E+02 --<u 3.00E+02 -3 = 2.50E+02 T E < 2.00E+02 -L o •S 1.50E+02 -a * 1.00E+02 y 5.00E+01 -0.00E+00 * 1 i •** ' 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.7e-3 12.2 3 (1/T1) ave 12.1 1.2 8.1e-7 0 T l ave 1.2 392 97 1.2 T l lgmn 1.0 103 Series 116 - 100% water-wet sand saturated with pore water of pH 7/1.0 M NaCl. 3.00E+02 2.50E+02 B 2.00E+02 ^ 1.50E+02-T CJ > « 1.00E+02 CJ 05 5.00E+01 0.00E+00 1.00E-03 1.00E-02 1.00E-01 T l (s) 1.OOE+00 -I .00E+01 T l (s) 1.4e-2 1.2 Amplitude 4.4 274 Percent 1.6 98.4 (1/TI) ave 1.9 T l ave 1.2 T l lgmn 1.1 104 Series 119 - 100% water-wet sand saturated with pore water of pH 9/0.01 M NaCl. 3.00E+02 2.50E+02 •a 2 2.00E+02 | < 1.50E+02 cu « 1.00E+02 cu 5.00E+01 + 0.00E+00 1.00E-03 -> 1.00E-02 1.00E-01 T l (s) 1.00E+00 .00E+01 T l (s) Amplitude Percent 2.9e-2 5.9 2.1 (1/T1) ave 1.5 1.2 6.3e-ll 0 T l ave 1.3 269 97.9 1.2 T l lgmn 1.2 105 Series 122 - 100% water-wet sand saturated with pore water of p H 9/0.1 M NaCl. 3.00E+02 j 2.50E+02 3 2.00E+02 "S. E ^ 1.50E+02 « 1.00E+02 | PS 5.00E+01 0.00E+00 I.00E-03 .00E-02 1.00E-01 T l (s) .OOE+00 -I 1.00E+01 T l (s) 1.5e-2 1.2 1.2 Amplitude 3.0 2.5e-7 283 Percent 1 0 99 (1/TI) ave 1.5 T l ave 1.2 T l lgmn 1.2 106 Series 126 - 100% water-wet sand saturated with pore water of pH 9/1.0 M NaCl. 3.00E+02 2.50E+02 - 2.00E+02 "a, c < 1.50E+02 2 1.00E+02 cu 5.00E+01 0.00E+00 1.00E-03 .00E-02 1.00E-01 T l (s) 1.00E+00 1.00E+01 T l (s) Amplitude Percent 1.6e-2 3.6 1.3 (1/T1) ave 1.7 1.1 1.0e-7 0 T l ave 1.2 272 98.7 1.2 T l lgmn 1.1 107 Series 135 - 100% water-wet sand saturated with pore water of pH 11/0.01 M NaCl. 3.00E+02 2.50E+02 -a | 2.00E+02 "o. E < 1.50E+02 cu > J5 1.00E+02 cu Pi 5.00E+01 0.00E+00 .00E-03 .00E-02 1.00E-01 T l (s) .00E+00 .00E+01 T l (s) Amplitude Percent 2.2e-2 1.7 1.6 (1/T1) ave 1.6 1.2 2.2e-7 0 T l ave 1.2 270 98.4 1.2 T l lgmn 1.1 108 Series 138 - 100% water-wet sand saturated with pore water of pH 11/0.1 M NaCl. 3.00E+02 T 2.50E+02 4> 3 2.00E+02 -"5, E < 1.50E+02 --CU > J* 1.00E+02 -cu 05 5.00E+01 -0.00E+00 -i 1 « -i \ 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.2e-2 2.0 0.7 (1/TI) ave 1.5 1.0e-l 2.6 0.9 T l ave 1.2 1.0e-9 0 1.2 1.2 282 98.4 T l lgmn 1.2 109 Series 142 - 100% water-wet sand saturated with pore water of pH 11/1.0 M NaCl. 3.00E+02 2.50E+02 T 3 2 2.00E+02 "5. B < 1.50E+02 « 1.00E+02 5.00E+01 0.00E+00 1.00E-03 1.00E-02 1.00E-01 T l (s) .00E+00 1.00E+01 1.2 264 99.1 T l (s) Amplitude Percent 3.2e-2 2.5 0.9 (1/T1) ave 1.1 T l ave 1.2 T l lgmn 1.2 110 Series 187 - pH 1.85/0.01 M NaCl pore water extracted from 100% water-wet sand. 2.50E+02 T 2.00E+02 o. 1.50E+02 E < | 1.00E+02 OS 5.00E+01 0.00E+00 1.00E-03 1.00E-02 1.00E-01 T l (s) 1.OOE+00 -J .00E+01 T l (s) 2.0 2.0 Amplitude 4.5e-7 240 Percent 0 100 (1/TI) ave 4.9e-l T l ave 2.0 T l lgmn 2.0 111 Series 188 - pH 3/0.01 M NaCl pore water extracted from 100% water-wet sand. 2.50E+02 j 2.00E+02 a. 1.50E+02 S < > 1.00E+02 ~Z OS 5.00E+01 0.00E+00 -! 1 : : 1 i 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) 3.0 208 99.9 T l (s) Amplitude Percent 9.2e-2 1.2e-l 0.1 (1/T1) ave 3.4e-l T l ave 3.0 T l lgmn 3.0 112 Series 192 - pH 5/0.01 M NaCl pore water extracted from 100% water-wet sand. 1.80E+02 j 1.60E+02 I 1.40E+02 -at •a | 1.20E+02 -"a. B 1.00E+02 -< <u 8.00E+01 -jjj 6.00E+01 -* 4.00E+01 --2.00E+01 -0.00E+00 -I 1 •—i 1 1 > 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 3.9e-2 3 .5e- l 0.2 (1/T1) ave 3.8e- l 3.0 3.8e-9 0 T l ave 3.1 163 99.8 3.1 T l lgmn 3.1 113 Series 191 - pH 7/0.01 M NaCl pore water extracted from 100% water-wet sand. 2.50E+02 2.00E+02 CU 3 l i 1.50E+02 c < | 1.00E+02 cu 5.00E+01 0.OOE+00 -i 1 1 •• II > 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) 3.1 232 100 T l (s) Amplitude Percent 3.0 3.8e-9 0 (1/TI) ave 3.2e-l T l ave 3.1 T l Igmn 3.1 114 Series 194- pH 9/0.01 M NaCl pore water extracted from 100% water-wet sand. 3.00E+02 T 2.50E+02 3 2.00E+02 E < 1.50E+02 « 1.00E+02 5.00E+01 0.00E+00 1.00E-03 1.00E-02 1.00E-01 T l (s) .OOE+00 .00E+01 T l (s) Amplitude Percent 3.3e-2 1.1 0.4 (1/TI) ave 4.4e-l 3.0 9.1e-10 0 T l ave 3.1 282 99.6 3.1 T l lgmn 3.1 115 Series 196 - p H 11/0.01 M NaCl pore water extracted from 100% water-wet sand. 4.00E+02 T 3.50E+02 -<u 3.00E+02 -•v 3 = 2.50E+02 -E < 2.00E+02 J-eu •S 1.50E+02 J-cu 0 5 1.00E+02 -5.00E+01 -0.00E+00 1 • ' 'I > 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) 3.1 367 100 T l (s) Amplitude Percent 3.0 7.2e-8 0 (1/T1) ave 3.2e- l T l ave 3.1 T l lgmn 3.1 116 Series 183 - 100% oil-wet sand saturated with pore water of pH 1.85/0.01 M NaCl. 2.50E+02 2.00E+02 3 a 1.50E+02 E < .00E+02 5.00E+01 0.00E+00 1.00E-03 1.00E-02 1.00E-01 T l (s) 1.00E+00 1.00E+01 T l (s) Amplitude Percent l.le-1 4.5 1.9 (1/T1) ave 7.3e-l 1.8 233 98.1 T l ave 1.7 T l lgmn 1.7 117 Series 131 - 100% oil-wet sand saturated with pore water of pH 1.85/0.01 M NaCl. 3.00E+02 2.50E+02 T 3 2 2.00E+02 "3. c < 1.50E+02 J3 1.00E+02 06 5.00E+01 0.00E+00 .00E-03 .OOE-02 1.00E-01 T l (s) .OOE+00 -i .00E+01 T l (s) l.le-2 1.3 1.4 Amplitude 2.6 7.4e-8 268 Percent 1 0 99 (1/TI) ave 1.6 T l ave 1.4 T l lgmn 1.3 118 Series 130 - 100% oil-wet sand saturated with pore water of pH 1.85/0.1 M NaCl. 3.00E+02 2.50E+02 cu •a 3 2.00E+02 "5. E < 1.50E+02 cu « 1.00E+02 cu 5.00E+01 + 0.00E+00 1.00E-03 J 1.00E-02 1.00E-01 T l (s) 1.00E+00 1.00E+01 T l (s) Amplitude Percent 1.5e-2 3.2 1.2 (1/T1) ave 1.4 1.6 8.2e-7 0 T l ave 1.7 266 98.8 1.6 T l Igmn 1.6 119 Series 129 - 100% oil-wet sand saturated with pore water of pH 1.85/1.0 M NaCl. 3.00E+02 2.50E+02 T 3 5 2.00E+02 < 1.50E+02 1 1.00E+02 + as 5.00E+01 0.00E+00 .00E-03 1.00E-02 1.00E-01 T l (s) 1.00E+00 -I 1.00E+01 T l (s) 9.0e-3 1.5 1.6 Amplitude 2.2 2.6e-7 256 Percent 0.8 0 99.2 (1/T1) ave 1.6 T l ave 1.6 T l lgmn 1.5 120 Series 144 - 100% oil-wet sand saturated with pore water of pH 3/0.01 M NaCl. 3.00E+02 2.50E+02 | cu 2 2.00E+02 "5, E < 1.50E+02 cu > 1 1.00E+02 cu 05 5.00E+01 0.00E+00 -! 1 « 1 1 1 » 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.0e-2 3.3 1.2 (1/T1) ave 1.1 1.8 1.6e-6 0 T l ave 1.9 272 98.8 1.8 T l lgmn 1.8 121 Series 147 - 100% oil-wet sand saturated with pore water of pH 3/0.1 M NaCl. 3.00E+02 2.50E+02 5 2.00E+02 "5, E < 1.50E+02 « 1.00E+02 CU OS 5.00E+01 0.00E+00 .00E-03 1.00E-02 1.00E-01 T l (s) .00E+00 1.00E+01 2.0 288 99 T l (s) Amplitude Percent 2.6e-2 3.0 1 (1/T1) ave 8.8e-l T l ave 2.0 T l Igmn 1.9 122 Series 150 - 100% oil-wet sand saturated with pore water of pH 3/1.0 M NaCl. 3.50E+02 T 3.00E+02 -3 2.50E+02 3 g 2.00E+02 -< « 1.50E+02-£ 1.00E+02-1-5.00E+01 -0.00E+00 -I \-> 1 i 1 i 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.3e-2 4 1.3 (1/T1) ave 1.5 1.8 1.0e-7 0 T l ave 1.8 312 98.7 1.8 T l lgmn 1.7 123 Series 153 - 100% oil-wet sand saturated with pore water of pH 5/0.01 M NaCl. 3.50E+02 T 3.00E+02 •o 2.50E+02 3 2.00E+02 « 1.50E+02 4J 1.00E+02 PS 5.00E+01 t 0.00E+00 i 1.00E-03 .00E-02 1.00E-01 T l (s) .OOE+00 1.00E+01 T l (s) Amplitude Percent 2.2e-2 3.9 1.2 (1/TI) ave 9.2e-l 2.5 1.4e-4 0 T l ave 2.6 318 97 2.6 5.6 5.9 1.8 T l lgmn 2.5 124 Series 159 - 100% oil-wet sand saturated with pore water of pH 5/0.1 M NaCl. 3.00E+02 -2.50E+02 -itude 2.00E+02 -Ampl 1.50E+02 cu > Relat 1.00E+02 -5.00E+01 -0.00E+00 -1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 3.4e-2 2.8 1 (1/T1) ave 6.8e-l 2.5 7.1e-6 0 T l ave 2.6 263 99 2.6 T l lgmn 2.5 125 Series 156 - 100% oil-wet sand saturated with pore water of pH 5/1.0 M NaCl. 2.50E+02 2.00E+02 •o 3 lL 1.50E+02 E < | 1.00E+02 cs tu 5.00E+01 0.OOE+00 .00E-03 .00E-02 1.00E-01 T l (s) 1.OOE+00 .00E+01 T l (s) Amplitude Percent l.le-2 8.2e-l 0.3 (1/TI) ave 6.9e-l 2.5 1.6e-5 0 T l ave 2.6 243 99.7 2.6 T l lgmn 2.6 126 Series 184 - 100% oil-wet sand saturated with pore water of pH 7/0.01 M NaCl. 2.50E+02 j 2.00E+02 -eu 3 ^ 1.50E+02 --E < | 1.00E+02 -S3 "3 a 5.00E+01 -0.00E+00 -! ••*—« 1 1 -A-I 4 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.7e-2 3.6 1.6 (1/T1) ave 1.3 8.3e-l 4.2e-3 0 T l ave 2.1 3.8 1.7 2.9 3.0 220 96.8 T l lgmn 2.7 127 Series 132 - 100% oil-wet sand saturated with pore water of pH 7/0.01 M NaCl. 3.00E+02 T 2.50E+02 5 2.00E+02 "a, B ^ 1.50E+02 « 1.00E+02 cu 5.00E+01 0.00E+00 1.00E-03 .OOE-02 1.00E-01 T l (s) 1.00E+00 1.00E+01 2.5 252 99.1 T l (s) Amplitude Percent 2.0e-2 2.3 0.9 (1/T1) ave 8.4e-l T l ave 2.5 T l lgmn 2.4 128 Series 133 - 100% oil-wet sand saturated with pore water of pH 7/0.1 M NaCl. 3.00E+02 2.50E+02 2 2.00E+02 < 1.50E+02 > 2 1.00E+02 cu as 5.00E+01 0.00E+00 1.00E-03 .00E-02 1 . 0 0 E - 0 1 T l (s) 1.OOE+00 1.00E+01 2.4 260 99.1 T l (s) Amplitude Percent 1.9e-2 2.4 0.9 (1/TI) ave 8.9e-l T l ave 2.4 T l lgmn 2.3 129 Series 117 - 100% oil-wet sand saturated with pore water of pH 7.0/1.0 M NaCl. 3.00E+02 T 2.50E+02 --cu •a 3 2.00E+02 -"S. E < 1.50E+02 cu > 1 1.00E+02 -cu B6 5.00E+01 -0.00E+00 ' 1 — —< : J' 1 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.6e-2 9.5e-l 0.4 (1/TI) ave 6.7e-l 7.7e-2 9.1e-l 0.3 T l ave 2.5 261 99.3 2.5 T l lgmn 2.4 130 Series 120 - 100% oil-wet sand saturated with pore water of pH 9/0.01 M NaCl. 3.00E+02 T 2.50E+02 -cu •a 3 2.00E+02 -"5. E 1.50E+02 -cu 1 1.00E+02 -cu 05 5.00E+01 -0.OOE+00 -1 1—* 1 — i 1 1 > 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.4e-2 5.2 1.9 (1/TI) ave 1.8 1.6e-l 2.8 1 T l ave 2.7 262 97.1 2.6 T l lgmn 2.4 131 Series 123 - 100% oil-wet sand saturated with pore water of pH 9/0.1 M NaCl. 3.00E+02 j 2.50E+02 2 2.00E+02 "3. E < 1.50E+02 « 1.00E+02 OS 5.00E+01 0.00E+00 J 1 • 1 1 1 f 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.1e-2 3.5 1.4 (1/T1) ave 1.1 2.5 1.7e-6 0 T l ave 2.6 252 98.6 2.5 T l lgmn 2.4 132 Series 127 - 100% oil-wet sand saturated with pore water of pH 9/1.0 M NaCl. 1 3.00E+02 T I 2.50E+02 -CP 5 2.00E+02 -"o. E < 1.50E+02--CP > 1 1.00E+02 -CP PS 5.00E+01 -0.00E+00 -! 1 1 1 1 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 2.0e-2 1.9 0.7 (1/T1) ave 8.0e-l 9.7e-2 1.5 0.6 T l ave 2.5 5.8e-6 0 2.6 2.6 257 98.7 T l lgmn 2.5 133 Series 136 - 100% oil-wet sand saturated with pore water of pH 11/0.01 M NaCl. 3.00E+02 2.50E+02 3 2.00E+02 H E < 1.50E+02 > « 1.00E+02 cu 2 . 5.00E+01 + 0.00E+00 .00E-03 1.00E-02 1.00E-01 T l (s) 1.OOE+00 1.00E+01 T l (s) Amplitude Percent 9.0e-3 2.6 1 (1/TI) ave 1.4 2.8 4.8e-ll 0 T l ave 2.9 260 99 2.8 T l lgmn 2.7 134 Series 185 - 100% oil-wet sand saturated with pore water of pH 11/0.01 M NaCl. 2.50E+02 T 2.00E+02 •o 3 % 1.50E+02 E < | 1.00E+02 ja <u 5.00E+01 0.00E+00 i 1 1 : 1 ^ 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.2e-2 1.7 0.7 (1/T1) ave 9.4e-l 3.0 5.8e-9 0 T l ave 3.1 229 99.3 3.0 T l lgmn 2.9 135 Series 139 - 100% oil-wet sand saturated with pore water of p H 11/0.1 M NaCl. 3.00E+02 T 2.50E+02 -cu 2 2.00E+02 --"5. E < 1.50E+02--cu > 2 1.00E+02 -cu PS 5.00E+01 -0.00E+00 -! 1—« : i 1 r 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.5e-2 3.7 1.4 (1/T1) ave 1.3 2.6 7.3e-6 0 T l ave 2.7 271 98.6 2.7 T l Igmn 2.6 136 Series 143 - 100% oil-wet sand saturated with pore water of pH 11/1.0 M NaCl. 3.00E+02 j 2.50E+02 -O) 5 2.00E+02 -"a. E < 1.50E+02 ->• « 1.00E+02 --03 5.00E+01 -0.00E+00 -I 1 1 1 J k 1.00E-03 1.00E-02 1.00E-01 1 .OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 1.4e-2 1.6 0.6 (1/TI) ave 8.3e-l 2.8 254 99.4 T l ave 2.8 T l lgmn 2.7 137 Series 186 - pH 1.85/0.01 M NaCl pore water extracted from 100% oil-wet sand. 2.50E+02 T 2.00E+02 -0> T3 3 -4-) L 1.50E+02 --E < | 1.00E+02 --a "3 os 5.00E+01 --0.OOE+00 1.00E-03 1.00E-02 1.00E-01 T l (s) .OOE+00 .00E+01 T l (s) Amplitude Percent 2.2 211 100 (1/TI) ave 4.5e-l T l ave 2.2 T l lgmn 2.2 138 Series 189 - pH 3/0.01 M NaCl pore water extracted from 100% oil-wet sand. 1.80E+02 T 1.60E+02 -1.40E+02 T cu "O 5 1.20E+02--E 1.00E+02 -« 8.00E+01 -> « 6.00E+01 T cu 4.00E+01 -• 2.00E+01 -0.00E+00 J 1 • 1 1 1 1. 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) 2.8 175 100 T l (s) Amplitude Percent 2.6 3.2e-8 0 (1/T1) ave 3.6e-l T l ave 2.8 T l lgmn 2.8 139 Series 193 - pH 5/0.01 M NaCl pore water extracted from 100% oil-wet sand. 2.00E+02 T 1.80E+02 1.60E+02 | 1.40E+02 ^ 1.20E+02 a < 1.00E+02 > 8.00E+01 ea « 6.00E+01 os 4.00E+01 2.00E+01 0.00E+00 + 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 T l (s) I.00E+01 T l (s) 3.0 3.1 Amplitude 1.9e-8 182 Percent 0 100 (1/TI) ave 3.3e-l T l ave 3.1 T l lgmn 3.1 140 Series 190 - pH 7/0.01 M NaCl pore water extracted from 100% oil-wet sand. 2.50E+02 2.00E+02 .50E+02 + > 1.00E+02 5.00E+01 0.00E+00 .00E-03 .00E-02 1.00E-01 T l (s) .OOE+00 1.00E+01 T l (s) 3.0 3.1 Amplitude 1.9e-8 231 Percent 0 100 (1/TI) ave 3.3e-l T l ave 3.1 T l lgmn 3.1 141 Series 195 - pH 9/0.01 M NaCl pore water extracted from 100% oil-wet sand. 3.50E+02 T 3.00E+02 -•S 2.50E+02 --s g 2.00E+02 -< « 1.50E+02 -es £ 1.00E+02 •• 5.00E+01 -0.00E+00 1 i : li i 1 .00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 T l (s) T l (s) Amplitude Percent 3.1 347 100 (1/T1) ave 3.2e-l T l ave 3.1 T l lgmn 3.1 142 Series 197 - pH 11/0.01 M NaCl pore water extracted from 100% oil-wet sand. 5.00E+02 T 4.50E+02 -4.00E+02 -| 3.50E+02 ± ^ 3.00E+02 -E < 2.50E+02 T | 2.00E+02 --"3 1.50E+02 -05 1.00E+02 T 5.00E+01 -0.OOE+00 J 1 — 1 1 -I • 1.00E-03 1.00E-02 1.00E-01 1.OOE+00 1.00E+01 T l (s) T l (s) Amplitude Percent 3.2 455 100 (1/TI) ave 3.2e-l T l ave 3.2 T l lgmn 3.2 143 A P P E N D I X E This appendix is a collection of S E M photomicrographs from the second part of the text titled: "Investigations of T, relaxation mechanisms on oil- and water-wet sand packs saturated with acidic, alkaline and saline water." 144 These photomicrographs were taken with the Scanning Electron Microscope. The first figure is a picture of Ottawa sand used in these N M R studies. The white spots on the grains are primarily pyrite (FeS2). The second figure is a close-up of the circled grain in the first photomicrograph. The bright spots, or pyrite areas, are clearer in this close-up view. 145 - a y D i s p l a y 1 _ l 1674 FS — • / r g p _ 2 0 td S i F e L A : i ~ — • — i — — • — * , — • • , I.I 2 . 0 4 . 0 6 . 0 8 . 0 1 0 . 0 k e V The upper photomicrograph is of iron-stained quartz grains from separated Ottawa sand. It is intended to show that the separator does not remove all of the iron from the sands. The bright coating on the gray quartz grain is ferric oxide. The lower figure is an electron microprobe chemical analysis showing its composition is confirmed as ferric oxide. 146 The upper photomicrograph is o f another iron-stained quartz sand grain from the separated Ottawa sand. The bright spots are again ferric. In the crevices on the quartz bright-spot coatings we conf i rm that the smal l round balls are pyrite (bottom micrograph). 147 

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