A Mechanistic Model for Wettability Alteration by Chemically Tuned Waterflooding in Carbonate Reservoirs
- Changhe Qiao (Pennsylvania State University) | Li Li (Pennsylvania State University) | Russell T. Johns (Pennsylvania State University) | Jinchao Xu (Pennsylvania State University)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- August 2015
- Document Type
- Journal Paper
- 767 - 783
- 2015.Society of Petroleum Engineers
- enhanced oil recovery, PennSim, reactive transport, low salinity
- 11 in the last 30 days
- 761 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
Injection of chemically tuned brines into carbonate reservoirs has been reported to enhance oil recovery by 5–30% original oil in place (OOIP) in coreflooding experiments and field tests. One proposed mechanism for this improved oil recovery (IOR) is wettability alteration of rock from oil-wet or mixed-wet to more-water-wet conditions. Modeling of wettability-alteration experiments, however, is challenging because of the complex interactions among ions in the brine and crude oil on the solid surface. In this research, we developed a multiphase and multicomponent reactive transport model that explicitly takes into account wettability alteration from these geochemical interactions in carbonate reservoirs.
Published experimental data suggest that desorption of acidic-oil components from rock surfaces make carbonate rocks more water-wet. One widely accepted mechanism is that sulfate (SO42–) replaces the adsorbed carboxylic group from the rock surface, whereas cations (Ca2+, Mg2+) decrease the oil-surface potential. In the proposed mechanistic model, we used a reaction network that captures the competitive surface reactions among carboxylic groups, cations, and sulfate. These reactions control the wetting fractions and contact angles, which subsequently determine the capillary pressure, relative permeabilities, and residual oil saturations.
The developed model was first tuned with experimental data from the Stevns Klint chalk and then used to predict oil recovery for additional untuned experiments under a variety of conditions where IOR increased by as much as 30% OOIP, depending on salinity and oil acidity. The numerical results showed that an increase in sulfate concentration can lead to an IOR of more than 40% OOIP, whereas cations such as Ca2+ have a relatively minor effect on recovery (approximately 5% OOIP). Physical parameters, including the total surface area of the rock and the diffusion coefficients, control the rate of recovery, but not the final oil recovery. The simulation results further demonstrate that the optimum brine formulations for chalk are those with relatively abundant SO42– (0.096 mol/kg water), moderate concentrations of cations, and low salinity (total ionic strength of less than 0.2 mol/kg water). These findings are consistent with the experimental data reported in the literature. The new model provides a powerful tool to predict the IOR potential of chemically tuned waterflooding in carbonate reservoirs under different scenarios. To the best of our knowledge, this is the first model that explicitly and mechanistically couples multiphase flow and multicomponent surface complexation with wettability alteration and oil recovery for carbonate rocks specifically.
|File Size||2 MB||Number of Pages||17|
Alotaibi, M., Azmy, R. and Nasr-El-Din, H. 2010. Wettability Challenges in Carbonate Reservoirs. Presented at the SPE Improved Oil Recovery Symposium, Tulsa, Oklahoma, 24–28 April. SPE-129972-MS. http://dx.doi.org/10.2118/129972-MS.
Andersen, P., Evje, S., Madland, M. V., et al. 2012. A Geochemical Model for Interpretation of Chalk Core Flooding Experiments. Chem. Eng. Sci. 84 (24 December): 218–241. http://dx.doi.org/10.1016/j.ces.2012.08.038.
Anderson, W. G. 1987. Wettability Literature Survey Part 5: The Effects of Wettability on Relative Permeability. J Pet Technol 39 (11): 1453–1468. SPE-16323-PA. http://dx.doi.org/10.2118/16323-PA.
Austad, T., Shariatpanahi, S. F., Strand, S., et al. 2012. Conditions for a Low-Salinity Enhanced Oil Recovery (EOR) Effect in Carbonate Oil Reservoirs. Energ. Fuel. 26 (1): 569–575. http://dx.doi.org/10.1021/ef201435g.
Austad, T., Strand, S., Madland, M. V., et al. 2008. Seawater in Chalk: An EOR and Compaction Fluid. SPE Res Eval & Eng 11 (4): 648–654. SPE-118431-PA. http://dx.doi.org/10.2118/118431-PA.
Brady, P. V. and Krumhansl, J. L. 2012. A Surface Complexation Model of Oil–Brine–Sandstone Interfaces at 100°C: Low Salinity Waterflooding. J. Pet. Sci. Eng. 81 (January): 171–176. http://dx.doi.org/10.1016/j.petrol.2011.12.020.
Brady, P. V., Krumhansl, J. L. and Mariner, P. E. 2012. Surface Complexation Modeling for Improved Oil Recovery. Presented at the SPE Improved Oil Recovery Symposium, Tulsa, Oklahoma, 14–18. SPE-153744-MS. http://dx.doi.org/10.2118/153744-MS.
Borgwardt, R. H. and Bruce, K. R. 1986. Effect of Specific Surface Area on the Reactivity of CaO with SO2. AIChE J. 32 (2): 239–246. http://dx.doi.org/10.1002/aic.690320210.
Bruemmer, G. W., Gerth, J. and Tiller, K. G. 1988. Reaction Kinetics of the Adsorption and Desorption of Nickel, Zinc and Cadmium by Goethite. I. Adsorption and Diffusion of Metals. J. Soil Sci. 39 (1): 37–52. http://dx.doi.org/10.1111/j.1365-2389.1988.tb01192.x.
Buckley, J. 1994. Chemistry of the Crude Oil/Brine Interface. Proc., 3rd International Symposium on Evaluation of Reservoir Wettability and Its Effect on Oil Recovery, Laramie, Wyoming, 21–23 September, 33–38.
Buckley, J. S. and Liu, Y. 1998. Some Mechanisms of Crude Oil/Brine/Solid Interactions. J. Pet. Sci. Eng. 20 (3–4): 155–160. http://dx.doi.org/10.1016/S0920-4105(98)00015-1.
Buckley, J. S., Bousseau, C. and Liu, Y. 1996. Wetting Alteration by Brine and Crude Oil: From Contact Angles to Cores. SPE J. 1 (3): 341–350. SPE-30765-PA. http://dx.doi.org/10.2118/30765-PA.
Cassie, A. B. D. 1948. Permeability to Water and Water Vapour of Textiles and Other Fibrous Materials. Introductory Paper. Discuss. Faraday Soc. 3: 239–243. http://dx.doi.org/10.1039/DF9480300239.
Chapman, D. 1913. A Contribution to the Theory of Electrocapillarity. Philos. Mag. 25 (148): 475–481. http://dx.doi.org/10.1080/14786440408634187.
Coats, K. H. 2000. A Note on IMPES and Some IMPES-Based Simulation Models. SPE J. 5 (3): 245–251. SPE-65092-PA. http://dx.doi.org/10.2118/65092-PA.
Dang, C. T. Q., Nghiem, L. X., Chen, Z. J., et al. 2013. Modeling Low Salinity Waterflooding: Ion Exchange Geochemistry and Wettability Alteration. Presented at SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, 30 September–2 October. SPE-166447-MS. http://dx.doi.org/10.2118/166447-MS.
Davis, J. A., James, R. O. and Leckie, J. O. 1978. Surface Ionization and Complexation at the Oxide/Water Interface: I. Computation of Electrical Double Layer Properties in Simple Electrolytes. J. Colloid Interf. Sci. 63 (3): 480–499. http://dx.doi.org/10.1016/S0021-9797(78)80009-5.
Davis, J. A., Meece, D. E., Kohler, M., et al. 2004. Approaches to Surface Complexation Modeling of Uranium (VI) Adsorption on Aquifer Sediments. Geochim. Cosmochim. Ac. 68 (18): 3621–3641. http://dx.doi.org/10.1016/j.gca.2004.03.003.
Delshad, M., Lenhard, R. J., Oostrom, M., et al. 2003. A Mixed-Wet Hysteretic Relative Permeability and Capillary Pressure Model for Reservoir Simulations. SPE Res Eval & Eng 6 (5): 328–334. SPE-86916-PA. http://dx.doi.org/10.2118/86916-PA.
Delshad, M., Najafabadi, N. F., Anderson, et al. 2009. Modeling Wettability Alteration by Surfactants in Naturally Fractured Reservoirs. SPE Res Eval & Eng 12 (3): 361–370. SPE-100081-PA. http://dx.doi.org/10.2118/100081-PA.
Drummond, C. and Israelachvili, J. 2004. Fundamental Studies of Crude Oil–Surface Water Interactions and its Relationship to Reservoir Wettability. J. Pet. Sci. Eng. 45 (1–2): 61–81. http://dx.doi.org/10.1016/j.petrol.2004.04.007.
Dzombak, D. and Morel, F. 1990. Surface Complexation Modeling: Hydrous Ferric Oxide. Hoboken, New Jersey: John Wiley & Sons.
Evje, S. and Hiorth, A. 2011. A Model for Interpretation of Brine-Dependent Spontaneous Imbibition Experiments. Adv. Water Resour. 34 (12): 1627–1642. http://dx.doi.org/10.1016/j.advwatres.2011.09.003.
Fathi, S. J., Austad, T. and Strand, S. 2010. “Smart Water” as a Wettability Modifier in Chalk: The Effect of Salinity and Ionic Composition. Energ. Fuel. 24 (4): 2514–2519. http://dx.doi.org/10.1021/ef901304m.
Fathi, S. J., Austad, T. and Strand, S. 2011. Water-Based Enhanced Oil Recovery (EOR) by “Smart Water”: Optimal Ionic Composition for EOR in Carbonatese. Energ. Fuel. 25 (11): 5173–5179. http://dx.doi.org/10.1021/ef201019k.
Fung, L. S.-K., Hiebert, A. D. and Nghiem, L. X. 1992. Reservoir Simulation with a Control-Volume Finite-element Method. SPE Res Eval & Eng 7 (3): 349–357. SPE-21224-PA. http://dx.doi.org/10.2118/21224-PA.
Fuller, C. C., Davis, J. A. and Waychunas, G. A. 1993. Surface Chemistry of Ferrihydrite: Part 2. Kinetics of Arsenate Adsorption and Coprecipitation. Geochim. Cosmochim. Ac. 57 (10): 2271–2282. http://dx.doi.org/10.1016/0016-7037(93)90568-H.
Gibbs, J. 1948. The Collected Works of J. Willard Gibbs, Vol. 1. New Haven, Connecticut: Yale University Press.
Gouy, G. 1910. On the Formation of Electrical Charges at the Surface of an Electrolyte. J. Physique 9: 457– 469. http://dx.doi.org/10.1051/jphystap:019100090045700.
Gupta, R. and Mohanty, K.K. 2011. Wettability Alteration Mechanism for Oil Recovery from Fractured Carbonate Rocks. Transport Porous Med. 87 (2): 635–652. http://dx.doi.org/10.1007/s11242-010-9706-5.
Hallenbeck, L. D., Sylte, J. E., Ebbs, D. J., et al. 1991. Implementation of the Ekofisk Field Waterflood. SPE Form Eval 6 (3): 284–290. SPE-19838-PA. http://dx.doi.org/10.2118/19838-PA.
Helgeson, H. C., Brown, T. H., Nigrini, A., et al. 1970). Calculation of Mass Transfer in Geochemical Processes Involving Aqueous Solutions. Geochim. Cosmochim. Ac. 34 (5): 569–592. http://dx.doi.org/10.1016/0016-7037(70)90017-7.
Helland, J. O. and Skjaeveland, S. M. 2006. Physically Based Capillary Pressure Correlation for Mixed-Wet Reservoirs From a Bundle-of-Tubes Model. SPE J. 11 (2): 171–180. SPE-89428-PA. http://dx.doi.org/10.2118/89428-PA.
Hill, D. 1984. Diffusion Coefficients of Nitrate, Chloride, Sulphate, and Water in Cracked and Uncracked Chalk. Journal of Soil Science 35 (1): 27–33. http://dx.doi.org/10.1111/j.1365-2389.1984.tb00256.x.
Hiorth, A., Cathles, L. M. and Madland, M. V. 2010. The Impact of Pore Water Chemistry on Carbonate Surface Charge and Oil Wettability. Transport Porous Med. 85 (1):1–21. http://dx.doi.org/10.1007/s11242-010-9543-6.
Hirasaki, G. and Zhang, D. L. 2004. Surface Chemistry of Oil Recovery From Fractured, Oil-Wet Carbonate Formations. SPE J. 9 (2): 151–162. SPE-88365-PA. http://dx.doi.org/10.2118/88365-PA.
Hjelmeland, O. S. and Larrondo, L. E. 1986. Experimental Investigation of the Effects of Temperature Pressure and Crude Oil Composition on Interfacial Properties. SPE Res Eval & Eng 1 (4): 321–328. SPE-12124-PA. http://dx.doi.org/10.2118/12124-PA.
Høgnesen, E. J., Standnes, D. C. and Austad, T. 2006. Experimental and Numerical Investigation of High Temperature Imbibition into Preferential Oil-Wet Chalk. J. Pet. Sci. Eng. 53 (1): 100–112. http://dx.doi.org/10.1016/j.petrol.2006.04.002.
Jerauld, G. R., Webb, K. J., Lin, C.-Y., et al. 2008. Modeling Low-Salinity Waterflooding. SPE Res Eval & Eng 11 (6): 1000–1012. http://dx.doi.org/10.2118/102239-PA.
Lager, A., Webb, K. J., Black, C. J. J., et al. 2006. Low Salinity Oil Recovery–An Experimental Investigation. Oral presentation given at the International Symposium of the Society of Core Analysts, Trondheim, Norway, 12–16 September.
Langmuir, D. 1997. Aqueaous Environmental Geochemistry. Upper Saddle River, New Jersey: Prentice Hall.
Li, L., Gawande, N., Kowalsky, M. B., et al. 2011. Physicochemical Heterogeneity Controls on Uranium Bioreduction Rates at the Field Scale. Environ. Sci. Technol. 45 (23): 9959–9966. http://dx.doi.org/10.1021/es201111y.
Li, L., Steefel, C. I., Kowalsky, M. B., et al. 2010. Effects of Physical and Geochemical Heterogeneities on Mineral Transformation and Biomass Accumulation During Biostimulation Experiments at Rifle, Colorado. J. Contam. Hydrol. 112 (1): 45–63. http://dx.doi.org/10.1016/j.jconhyd.2009.10.006.
Lichtner, P. C. 1985. Continuum Model for Simultaneous Chemical Reactions and Mass Transport in Hydrothermal Systems. Geochim. Cosmochim. Ac. 49 (3): 779–800. http://dx.doi.org/10.1016/0016-7037(85)90172-3.
Lichtner, P. C. 1996. Continuum formulation of multicomponent-multiphase reactive transport. In Reactive Transport in Porous Media, Reviews in Mineralogy, 34, 1–81.
McGuire, P. L., Chatham, J. R., Paskvan, F. K., et al. 2005. Low Salinity Oil Recovery: an Exciting New EOR Opportunity for Alaska’s North Slope. Presented at the SPE Western Regional Meeting, Irvine, California, 30 March–1 April. SPE-93903-MS. http://dx.doi.org/10.2118/93903-MS.
Megawati, M., Hiorth, A., and Madland, M. V. 2013. The Impact of Surface Charge on the Mechanical Behavior of High-Porosity Chalk. Rock Mechanics and Rock Engineering 46 (5): 1,073–1,090.
Morrow, N. R. 1990. Wettability and its Effect on Oil Recovery. J Pet Technol 42 (12): 1476–1484. SPE-21621-PA. http://dx.doi.org/10.2118/21621-PA.
Nasralla, R. A. and Nasr-El-Din, H. A. 2012. Double-Layer Expansion : Is It A Primary Mechanism of Improved Oil Recovery by Low-Salinity Waterflooding. Presented at the SPE Improved Oil Recovery Symposium, Tulsa, Oklahoma, 14–18 April. SPE-154334-MS. http://dx.doi.org/10.2118/154334-MS.
O'Carroll, D. M., Abriola, L. M., Polityka, C. A. et al. 2005. Prediction of two-phase capillary pressure–saturation relationships in fractional wettability systems. Journal of Contaminant Hydrology 77 (4): 247–270. http://dx.doi.org/10.1016/j.jconhyd.2005.01.004.
Owens, W. W. and Archer, D. L. 1971.The Effect of Rock Wettability on Oil-Water Relative Permeability Relationships. J Pet Technol 23 (7): 873–878. SPE-3034-PA. http://dx.doi.org/10.2118/3034-PA.
PennSim Toolkit. 2013. Gas Flooding Joint Industry Project, EMS Energy Institute, Pennsylvania State University, University Park, Pennsylvania.
Peters, E. J. 2012. Advanced Petrophysics: Solutions, Vol. 3. Austin, Texas: Live Oak Book Company.
Puntervold, T. and Austad, T. 2008. Injection of Seawater and Mixtures with Produced Water into North Sea Chalk Formation: Impact of Fluid–Rock Interactions on Wettability and Scale Formation. J. Pet. Sci. Eng. 63 (1–4): 23–33. http://dx.doi.org/10.1016/j.petrol.2008.07.010.
Puntervold, T., Strand, S. and Austad, T. 2009. Coinjection of Seawater and Produced Water to Improve Oil Recovery From Fractured North Sea Chalk Oil Reservoirs. Energ. Fuel. 23 (5): 2527–2536. http://dx.doi.org/10.1021/ef801023u.
Puntervold, T., Strand, S. and Austad, T. 2007. Waterflooding of Carbonate Reservoirs: Effects of a Model Base and Natural Crude Oil Bases on Chalk Wettability. Energ. Fuel. 28 (5): 1606–1616. http://dx.doi.org/10.1021/ef060624b.
RezaeiDoust, A., Puntervold, T., Strand, S., et al. 2009. Smart Water as Wettability Modifier in Carbonate and Sandstone: A Discussion of Similarities/Differences in the Chemical Mechanisms. Energ. Fuel. 23 (9): 4479–4485. http://dx.doi.org/10.1021/ef900185q.
Robertson, E. P. 2007. Low-Salinity Waterflooding to Improve Oil Recovery-Historical Field Evidence. Presented at the SPE Annual Technical Conference and Exhibition, Anaheim, California, 11–14 November. SPE-109965-MS. http://dx.doi.org/10.2118/109965-MS.
Rosen, M. J. and Kunjappu, J. T. 2012. Surfactants and Interfacial Phenomena. Hoboken, New Jersey: John Wiley & Sons.
Steefel, C. I. and Lasaga, A. C. 1994. A Coupled Model for Transport of Multiple Chemical Species and Kinetic Precipitation/Dissolution Reactions with Application to Reactive Flow in Single Phase Hydrothermal Systems. Am. J. Sci. 294 (5): 529–592. http://dx.doi.org/10.2475/ajs.294.5.529.
Steefel, C. I., DePaolo, D. J. and Lichtner, P. C. 2005. Reactive Transport Modeling: An Essential Tool and a New Research Approach for the Earth Sciences. Earth Planet Sc. Lett. 240 (3): 539–558. http://dx.doi.org/10.1016/j.epsl.2005.09.017.
Strand, S., Høgnesen, E. J. and Austad, T. 2006a. Wettability Alteration of Carbonates—Effects of Potential Determining Ions (Ca2+ and SO42–) and Temperature. Colloid. Surface. A 275 (1): 1–10. http://dx.doi.org/10.1016/j.colsurfa.2005.10.061.
Strand, S., Puntervold, T. and Austad, T. 2008. Effect of Temperature on Enhanced Oil Recovery From Mixed-Wet Chalk Cores by Spontaneous Imbibition and Forced Displacement Using Seawater. Energ. Fuel. 22 (5): 3222–3225. http://dx.doi.org/10.1021/ef800244v.
Strand, S., Standnes, D. C. and Austad, T. 2006b. New Wettability Test for Chalk Based on Chromatographic Separation of SCN– and SO42–. J. Pet. Sci. Eng. 52 (1): 187–197. http://dx.doi.org/10.1016/j.petrol.2006.03.021.
Strand, S., Standnes, D. C. and Austad, T. 2003. Spontaneous Imbibition of Aqueous Surfactant Solutions Into Neutral to Oil-Wet Carbonate Cores: Effects of Brine Salinity and Composition. Energ. Fuel. 17 (5): 1133–1144. http://dx.doi.org/10.1021/ef030051s.
Tang, G.-Q. and Morrow, N. R. 1999. Influence of Brine Composition and Fines Migration on Crude Oil/Brine/Rock Interactions and Oil Recovery. J. Pet. Sci. Eng. 24 (2–4): 99–111. http://dx.doi.org/10.1016/S0920-4105(99)00034-0.
Ustohal, P., Stauffer, F. and Dracos, T. 1998. Measurement and Modeling of Hydraulic Characteristics of Unsaturated Porous Media with Mixed Wettability. J. Contam. Hydrol. 33 (1–2): 5–37. http://dx.doi.org/10.1016/S0169-7722(98)00063-1.
Villalobos, M., Trotz, M. A. and Leckie, J. O. 2001. Surface Complexation Modeling of Carbonate Effects on the Adsorption of Cr(VI), Pb(II), and U(VI) on Goethite. Environ. Sci. Technol. 35 (19): 3849–3856. http://dx.doi.org/10.1021/ES001748K.
Walter, A. L., Frind, E. O., Blowes, D. W., et al. 1994. Modeling of Multicomponent Reactive Transport in Groundwater: 1. Model Development and Evaluation. Water Resour. Res. 30 (11): 3137–3148. http://dx.doi.org/10.1029/94WR00955.
Webb, K. J., Black, C. J. J. and Al-Ajeel, H. 2004. Low Salinity Oil Recovery–Log-Inject-Log. Presented at the SPE/DOE Symposium on Improved Oil Recovery, Tulsa, Oklahoma, 17–21 April. SPE-89379-MS. http://dx.doi.org/10.2118/89379-MS.
Webb, K. J., Black, C. J. J. and Tjetland, G. 2005. A Laboratory Study Investigating Methods for Improving Oil Recovery in Carbonates. Presented at the International Petroleum Technology Conference, Doha, Qatar, 21–23 November. IPTC-10506-MS. http://dx.doi.org/10.2523/10506-MS.
Wolery, T. J., Jackson, K. J., Bourcier, W.L., et al. 1990. Current Status of the EQ3/6 Software Package for Geochemical Modeling. In Chemical Modeling of Aqueous Systems II, Vol. 146, ed. D. C. Melchior and R. L. Bassett, Chapter 8, 104–116. Washington, DC: American Chemical Society. http://dx.doi.org/10.1021/bk-1990-0416.ch008.
Yeh, G.-T. and Tripathi, V. S. 1991. A Model for Simulating Transport of Reactive Multispecies Components: Model Development and Demonstration. Water Resour. Res. 27 (12): 3075–3094. http://dx.doi.org/10.1029/91WR02028.
Yildiz, H. O. and Morrow, N. R. 1996. Effect of Brine Composition on Recovery of Moutray Crude Oil by Waterflooding. J. Pet. Sci. Eng. 14 (3): 159–168. http://dx.doi.org/10.1016/0920-4105(95)00041-0.
Yousef, A. A., Al-Saleh, S., Al-Kaabi, A. U., et al. 2010. Laboratory Investigation of Novel Oil Recovery Method For Carbonate Reservoirs. Presented at the Canadian Unconventional Resources and International Petroleum Conference, Calgary, Alberta, Canada, 19–21 October. SPE-137634-MS. http://dx.doi.org/10.2118/137634-MS.
Yousef, A., Al-Saleh, S. and Al-Jawfi, M. S. 2011. Smart WaterFlooding for Carbonate Reservoirs: Salinity and Role of Ions. Presented at the SPE Middle East Oil and Gas Show and Conference, Manama, Bahrain, 25–28 September. SPE-141082-MS. http://dx.doi.org/10.2118/141082-MS.
Yousef, A. A., Al-Saleh, S. and Al-Jawfi, M. S. 2012a. Improved/Enhanced Oil Recovery from Carbonate Reservoirs by Tuning Injection Water Salinity and Ionic Content. Presented at the SPE Improved Oil Recovery Symposium, Tulsa, Oklahoma, 14–18 April. SPE-154076-MS. http://dx.doi.org/10.2118/154076-MS.
Yousef, A., Al-Saleh, S. and Al-Jawfi, M. S. 2012b. The Impact of the Injection Water Chemistry on Oil Recovery from Carbonate Reservoirs. Presented at the SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman, 16–18 April. SPE-154077-MS. http://dx.doi.org/10.2118/154077-MS.
Yousef, A.A., Liu, J. S., Blanchard, G. W., et al. 2012c. SmartWaterflooding: Industry’s First Field Test in Carbonate Reservoirs. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 8–10 October. SPE-159526-MS. http://dx.doi.org/10.2118/159526-MS.
Yu, L., Evje, S., Kleppe, H., et al. 2009. Spontaneous Imbibition of Seawater Into Preferentially Oil-Wet Chalk Cores—Experiments And Simulations. J. Pet. Sci. Eng. 66 (3): 171–179. http://dx.doi.org/10.1016/j.petrol.2009.02.008.
Zhang, P. and Austad, T. 2005a. Waterflooding in Chalk: Relationship Between Oil Recovery, New Wettability Index, Brine Composition And Cationic Wettability Modifier. Presented at the SPE Europec/EAGE Annual Conference, Madrid, Spain, 13–16 June. SPE-94209-MS. http://dx.doi.org/10.2118/94209-MS.
Zhang, P. and Austad, T. 2005b. The Relative Effects of Acid Number and Temperature on Chalk Wettability. Presented at SPE International Symposium on Oilfield Chemistry, The Woodlands, Texas, 2–4 February. SPE-92999-MS. http://dx.doi.org/10.2118/92999-MS.
Zhang, P. and Sparks, D. L. 1990. Kinetics and Mechanisms of Sulfate Adsorption/Desorption on Goethite Using Pressure-Jump Relaxation. Soil Science Society of America Journal 54 (5): 1,266–1,273. http://dx.doi.org/10.2136/sssaj1990.036159950054000500011x.
Zhang, P., Tweheyo, M. T. and Austad, T. 2006. Wettability Alteration and Improved Oil Recovery In Chalk: The Effect Of Calcium in The Presence Of Sulfate. Energ. Fuel. 20 (5): 2056–2062. http://dx.doi.org/10.1021/ef0600816.
Zhang, P., Tweheyo, M. T. and Austad, T. 2007. Wettability Alteration And Improved Oil Recovery By Spontaneous Imbibition of Seawater Into Chalk: Impact of The Potential Determining Ions Ca2+, Mg2+, and SO42–. Colloid. Surface. A 301 (1–3): 199–208. http://dx.doi.org/10.1016/j.colsurfa.2006.12.058.
Zysset, A., Stauffer, F. and Dracos, T. 1994. Modeling of Reactive Groundwater Transport Governed by Biodegradation. Water Resour. Res. 30 (8): 2423–2434. http://dx.doi.org/10.1029/94WR01045.