Core restoration: A guide for improved wettability assessments


Ivan Dario Pinerez Torrijos ; Tina Puntervold; Skule Strand; Panagiotis Aslanidis; Ingebret Fjelde; Aleksandr Mamonov


The National IOR Centre of Norway, EOR, smart water injections, reservoir systems, wettability, core restoration


The initial wetting of a reservoir sets a limit for the EOR potential during water-based recovery operations and “Smart Water” injection. For this reason, an improved understanding of the factors influencing the wetting can help to control and better forecast oil production during water-based floods. To preserve and reproduce the original reservoir wettability is a challenging task and wrong cleaning and core restoration procedures can lead to incorrect wettability estimations and thus induce serious errors when evaluating the initial wettability of a reservoir system or its EOR potential by water-based methods.

Thereby, there is a need to improve the chemical knowledge on interactions among the rock, brine and fluids present in reservoir systems. This will help to understanding the influence of the parameters affecting wettability during cleaning and core restoration processes. Understanding which are the main parameters influencing oil recovery processes is of great relevance.

The objective of this document is to provide suggestions for added-value experiments, complementing and challenging the standard RCA and SCAL procedures, prior to performing experimental research in which wettability and wettability alteration processes are important. Lessons learned will be highlighted and new ideas to optimize core restoration protocols to preserve and closely reproduce wettability are put forward. These recommended practices target core restoration procedures after the core material has been received in the laboratory.

The target audience for this document is engineers and scientists with an interest in core preparation for wettability studies.

Author Biographies

Ivan Dario Pinerez Torrijos

Faculty of Science and Technology
Department of Energy Resources
University of Stavanger

Tina Puntervold

Associate professor
Faculty of Science and Technology
Department of Energy Resources
University of Stavanger

Skule Strand

Associate professor
Faculty of Science and Technology
Department of Energy Resources
University of Stavanger

Panagiotis Aslanidis

Faculty of Science and Technology
Department of Energy Resources
University of Stavanger

Ingebret Fjelde

Faculty of Science and Technology
Department of Chemistry, Bioscience and Environmental Engineering
University of Stavanger

Aleksandr Mamonov

Faculty of Science and Technology
Department of Energy Resources


Abeysinghe, K. P., Fjelde, I. and Lohne, A. 2012. Dependency of remaining oil saturation on wettability and capillary number Paper SPE-160883 presented at the 2012 SPE Technical symposium and Exhibition, Al-Khobar, Saudi Arabia, 8-11 April.

Aghaeifar, Z., Puntervold, T., Strand, S., Austad, T., Maghsoudi, B. and Ferreira, J. d. C. 2018. Low Salinity EOR Effects After Seawater Flooding in a High Temperature and High Salinity Offshore Sandstone Reservoir. SPE Norway One Day Seminar, Bergen, Norway, 2018/4/18/.

Aghaeifar, Z., Strand, S., Austad, T., Puntervold, T., Aksulu, H., Navratil, K., Storås, S. and Håmsø, D. 2015. Influence of Formation Water Salinity/Composition on the Low-Salinity Enhanced Oil Recovery Effect in High-Temperature Sandstone Reservoirs. Energy & Fuels 29(8): 4747-4754.

Anderson, W. G. 1986. Wettability Literature Survey - Part 1: Rock/Oil/Brine interactions and the effects of core handling on wettability. Journal of Petroleum Technology October: 1125-1144.

API. 1998. Recommended Practices for Core Analysis, API Publishing Services.

Aslanidis, P., Strand, S., Pinerez Torrijos, I. D. and Puntervold, T. 2022. Reproducing wettability in sandstone reservoir core material in laboratory core restorations. Journal of Petroleum Science and Engineering 208: 109531.

Austad, T., RezaeiDoust, A. and Puntervold, T. 2010. Chemical mechanism of low salinity water flooding in sandstone reservoirs. Paper SPE 129767 prepared for presentation at the 2010 SPE Improved Oil Recovery Symposium, Tulsa, Oklahoma, USA, 24-28 April.

Austad, T., Shariatpanahi, S. F., Strand, S., Aksulu, H. and Puntervold, T. 2015. Low salinity EOR effects in limestone reservoir cores containing anhydrite: a discussion of the chemical mechanism. Energy & Fuels 29(11): 6903-6911.

Bobek, J. E., Mattax, C. C. and Denekas, M. O. 1958. Reservoir Rock Wettability - Its Significance and Evaluation. Transactions of the AIME 213(01): 155-160.

Buckley, J. S. (1994). Chemistry of the crude oil/brine interface. Proceedings of the 3rd International Symposium on Evaluation of Reservoir Wettability and Its Effect on Oil Recovery, Laramie, WY, USA.

Buckley, J. S. and Fan, T. 2007. Crude oil/brine interfacial tensions. Petrophysics (Houston, Tex.) 48(3): 175-185.

Buckley, J. S. and Liu, Y. 1998. Some mechanisms of crude oil/brine/solid interactions. Journal of Petroleum Science and Engineering 20: 155-160.

Buckley, J. S., Liu, Y. and Monsterleet, S. 1998. Mechanisms of wetting alteration by crude oils. SPE Journal March: 54-61.

Buckley, J. S. and Morrow, N. R. 1990. Characterization of crude oil wetting behavior by adhesion tests. Paper SPE/DOE 20263 presented at the SPE/DOE Seventh Symposium on Enhanced Oil Recovery, Tulsa, Oklahoma, April 22-25.

Cuiec, L. E. 1975. Restoration of the natural state of core samples - SPE 5634. The 50th annual fall meeting of the Society of Petroleum Engineers of AIME, Dallas, TX, USA, Sep 28 - Oct 1.

ESSO. 1966. Reservoir Engineering Manual. United States of America.

Fathi, S. J., Austad, T. and Strand, S. 2010. "Smart Water" as wettability modifier in chalk: The effect of salinity and ionic composition. Energy & Fuels 24: 2514-2519.

Fjelde, I. 2017. Effect of Mud Invasion on the Determined Low Salinity Water Flooding Potential. 2017(1): 1-14.

Fjelde, I. (2021). Effects of mud exposure on established wettability conditions. IOR NORWAY 2021-14th International sympoisum on reservoir wettability and its effects on oil recovery, Stavanger, Norway.

Fjelde, I., Voke, O. A. and Wetrhus Minde, M. 2015. Removal of mud components from reservoir sandstone rocks. International Symposium of the Society of Core Analysts held in St. John's Newfoundland and Labrador, Canada, 16-21 August, 2015 St. John's Newfoundland and Labrador, Canada.

Fulcher, R. A., Jr., Ertekin, T. and Stahl, C. D. 1985. Effect of capillary number and its constituents on two-phase relative permeability curves. Journal of Petroleum Technology 37(2): 249-260.

Gant, P. L. and Anderson, W. G. 1988. Core Cleaning for Restoration of Native Wettability. SPE Formation Evaluation 3(01): 131-138.

Grist, D. M., Langley, G. O. and Neustadter, F. L. 1975. The Dependence of Water Permeability On Core Cleaning Methods In the Case of Some Sandstone Samples. Journal of Canadian Petroleum Technology 14(02).

Guo, H., Dou, M., Hanqing, W., Wang, F., Yuanyuan, G., Yu, Z., Yansheng, W. and Li, Y. 2015. Review of capillary number in chemical enhanced oil Recovery. Paper SPE 175172 presented at the 2015 Oil and Gas Show and Conference, Mishref, Kuwait, 2015/10/11/.

Hopkins, Walrond, K., Strand, S., Puntervold, T., Austad, T. and Wakwaya, A. 2016a. Adsoprtion of acidic crude oil components onto outcrop chalk at different wetting conditions during both dynamic adsorption and aging processes. Energy & Fuels 30(9): 7229-7235.

Hopkins, P. A. (2016). Water-Based EOR and Initial Wettability in Carbonates, University of Stavanger.

Hopkins, P. A., Omland, I., Layti, F., Strand, S., Puntervold, T. and Austad, T. 2017. Crude Oil Quantity and Its Effect on Chalk Surface Wetting. Energy & Fuels 31(5): 4663-4669.

Hopkins, P. A., Strand, S., Puntervold, T., Austad, T., Dizaj, S. R., Waldeland, J. O. and Simonsen, J. C. 2016b. The adsorption of polar components onto carbonate surfaces and the effect on wetting. Journal of Petroleum Science and Engineering 147: 381-387.

Jadhunandan, P. P. and Morrow, N. R. 1995. Effect of wettability on waterflood recovery for crude-oil/brine/rock systems. SPE Reservoir Engineering February: 40-46.

Jennings, H. Y., Jr. 1957. Effect of Laboratory Core Cleaning on Water-Oil Relative Permeability.

Klewiah, I., Piñerez Torrijos, I. D., Strand, S., Puntervold, T. and Konstantinopoulos, M. 2019. Adsorption of Crude Oil Polar Components onto Silica-Rich Chalk and its Impact on Wetting. SPE Norway One Day Seminar, Bergen, Norway, 2019/5/13/.

Konstantinopoulos, M., Piñerez Torrijos, I. D., Klewiah, I., Strand, S. and Puntervold, T. 2019. Effect of Mineralogy on Initial Wettability and Oil Recovery from Silica-containing Chalk. 2019(1): 1-5.

Lopez-Salinas, J. L., Hirasaki, G. and Millar, C. A. 2011. Determination of anhydrite in reservoirs for EOR. Paper SPE 141420 presented at the SPE International Symposium on Oilfield Chemistry, The Woodlands, Texas, 11-13 April.

Mamonov, A., Kvandal, O. A., Strand, S. and Puntervold, T. 2019. Adsorption of Polar Organic Components onto Sandstone Rock Minerals and Its Effect on Wettability and Enhanced Oil Recovery Potential by Smart Water. Energy & Fuels 33(7): 5954-5960.

McPhee, C., Reed, J. and Zubizarreta, I. 2015. Core analysis: a best practice guide. Amsterdam, Netherlands, Elsevier.

Mjos, J. E. S., Strand, S., Puntervold, T. and Gaybaliyev, H. 2018. Effect of Initial Wetting on Smart Water Potential in Carbonates. Paper presented at the 2018 SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman, 2018/3/26/.

Piñerez, I., Puntervold, T., Strand, S., Hopkins, P., Aslanidis, P., Yang, H. S. and Kinn, M. S. 2020. Core wettability reproduction: A new solvent cleaning and core restoration strategy for chalk cores. Journal of Petroleum Science and Engineering 195: 107654.

Piñerez Torrijos, I. D., Mamonov, A., Strand, S. and Puntervold, T. 2020. The role of polar organic components in dynamic crude oil adsorption on sandstones and carbonates. CT&F - Ciencia, Tecnología y Futuro 10(2): 5-16.

Pinerez Torrijos, I. D., Puntervold, T., Strand, S., Austad, T., Abdullah, H. I. and Olsen, K. 2016. An experimental study of the response time of the low salinity EOR effect during secondary and tertiary low salinity waterflooding. IEA-EOR - 37th Annual Workshop & Symposium, Rueil Malmaison, 2016-09-18 - 2016-09-22.

Pinerez Torrijos, I. D., Risanger, M., Puntervold, T., Strand, S. and Austad, T. 2017. Impact of anhydrite on the low salinity EOR effect in sandstone material with high clay content. IOR NORWAY 2017 - 19th European Symposium on Improved Oil Recovery, Stavanger, 2017-04-24 - 2017-04-27.

Puntervold, T. 2008. Waterflooding of carbonate reservoirs - EOR by wettability alteration, University of Stavanger, Norway. ISBN 978-82-7644-347-9.

Puntervold, T., Mamonov, A., Piñerez Torrijos, I. D. and Strand, S. 2021. Adsorption of Crude Oil Components onto Carbonate and Sandstone Outcrop Rocks and Its Effect on Wettability. Energy & Fuels.

Puntervold, T., Strand, S. and Austad, T. 2007a. New method to prepare outcrop chalk cores for wettability and oil recovery studies at low initial water saturation. Energy & Fuels 21(6): 3425-3430.

Puntervold, T., Strand, S. and Austad, T. 2007b. Water Flooding of Carbonate Reservoirs: Effects of a Model Base and Natural Crude Oil Bases on Chalk Wettability. Energy & Fuels 21(3): 1606-1616.

Puntervold, T., Strand, S., Ellouz, R. and Austad, T. 2015. Modified seawater as a smart EOR fluid in chalk. Journal of Petroleum Science and Engineering 133: 440-443.

RezaeiDoust, A., Puntervold, T. and Austad, T. 2011. Chemical verification of the EOR mechanism by using low saline/smart water in sandstone. Energy & Fuels 25(5): 2151-2162.

Richardson, J. G., Holstein, E. D., Rathmell, J. J. and Warner, H. R., Jr. 1997. Validation of As-Received Oil-Based-Core Water Saturations From Prudhoe Bay. SPE Reservoir Engineering 12(01): 31-36.

Ringen, J. H., C; Lehne, K.A; Rueslaatten, H; Holand, H. 2001. Reservoir Water Saturations Measured on Cores; Case Histories and Recommendations. 6th Nordic Symposium on Petrophysics, 15-16 May.

Shariatpanahi, S. F., Strand, S., Austad, T. and Aksulu, H. 2012. Wettability restoration of limestone cores using core material from the aqueous zone. Petroleum Science and Technology 30(1-9).

Shimoyama, A. and Johns, W. D. 1971. Catalytic Conversion of Fatty Acids to Petroleum-like Paraffins and their Maturation. Nature Physical Science 232(33): 140-144.

Shimoyama, A. and Johns, W. D. 1972. Formation of alkanes from fatty acids in the presence of CaCO3. Geochimica et Cosmochimica Acta 36(1): 87-91.

Springer, N., Korsbech, U. and Aage, H. K. 2003. Resistivity index measurement without the porous plate: A desaturation technique based on evaporation produces uniform water saturation profiles and more reliable results for tight North Sea chalk. Paper presented at the International Symposium of the Society of Core Analysts Pau, France, 21-24 Sept.

Standnes, D. C. and Austad, T. 2000. Wettability alteration in chalk: 1. Preparation of core material and oil properties. Journal of Petroleum Science and Engineering 28(3): 111-121.

Treiber, L. E. and Owens, W. W. 1972. A laboratory evaluation of the wettability of fifty oil producing reservoirs. SPE Journal 12(6): 531-540.

Wendell, D. J., Anderson, W. G. and Meyers, J. D. 1987. Restored-State Core Analysis for the Hutton Reservoir. SPE Formation Evaluation 2(04): 509-517
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