Вестник нефтегазовой отрасли КазахстанаВестник нефтегазовой отрасли Казахстана2707-42262957-806XKMG Engineering10898510.54859/kjogi108985Research ArticleDevelopment of a laboratory methodology for core flooding experiments to evaluate gravity segregation in oil–water saturated porous mediaSagyndikovMarat<p>PhD</p>sagyndikov.marat.s@gmail.comhttps://orcid.org/0000-0003-0086-723XGussenovIskander<p>PhD</p>iskander.gussenov@gmail.comhttps://orcid.org/0000-0002-9820-7952MelisYerzhanyerzhan.melis@gmail.comhttps://orcid.org/0009-0003-7212-4993MatkirZhanabayzhanabaymatker@gmail.comhttps://orcid.org/0009-0007-7772-6466Institute of Polymer Materials and TechnologyResearching and DevelopmentSatbayev University3006202682941040805202603062026Copyright © 2026, Sagyndikov M., Gussenov I., Melis Y., Matkir Z.2026<p><strong>Background:</strong> High water cut increases operating costs and reduces oil recovery. Gravity-driven redistribution of oil and water during well shut-in periods has been proposed for reducing water cut; however, laboratory methodologies for investigating this phenomenon in core samples remain limited.</p> <p><strong>Aim: </strong>To develop a laboratory methodology for evaluating gravity segregation in oil–water saturated cores under controlled conditions.</p> <p><strong>Materials and methods:</strong> The methodology is based on epoxy-sealed cores fixed inside a sleeve, providing a practical and cost-effective core holder capable of accommodating pressure ports. Two experimental scenarios are considered: early water breakthrough caused by an unfavorable mobility ratio, and breakthrough induced by a high-permeability channel. After water breakthrough, flooding is suspended, the core is aged in a vertical position, and water injection is subsequently resumed. Effluent analysis is performed using a gravimetric oil–water separation technique based on the adhesion of oil to polyethylene. The methodology enables qualitative and quantitative assessment of fluid redistribution caused by gravity.</p> <p><strong>Results:</strong> Fractional flow analysis demonstrates that, when viscous oils are used, a significant fraction of mobile oil remains in the core after water breakthrough, whereas artificial high-permeability channels can be used to preserve low-viscosity mobile oil within the matrix for subsequent redistribution by gravity segregation.</p> <p><strong>Conclusion: </strong>The developed methodology provides a reliable and inexpensive platform for investigating gravity segregation in cores and may support the development of field technologies aimed at reducing water cut and improving oil recovery.</p>gravity segregationwater cutflow ratecore samplecore holderгравитациялық сегрегациясуланусүзу шығыныкерн үлгісікернұстағышгравитационная сегрегацияобводнённостьрасход фильтрацииобразец кернакернодержатель1.Kushekov R.M., Sagyndikov M.S., Ispanbetov T.K., et al. Full-Field Polymer Flooding Project – Principles and Challenges at the Kalamkas Oilfield // SPE Improved Oil Recovery Conference; April 22–25, 2024; Tulsa, Oklahoma, USA. Available from: onepetro.org/SPEIOR/proceedings-abstract/24IOR/24IOR/D021S007R003/544328.2.Al Ruqaishi A.S., Al Wahaybi M.H., Al Harthi N., et al. Enhancing Sweep Efficiency in Mature Waterflooded Carbonate Reservoirs in North Oman Through Advanced Chemical Water Shutoff Treatments // SPE Conference at Oman Petroleum & Energy Show; May 12–14, 2025; Muscat, Oman. Available from: onepetro.org/SPEOGWA/proceedings-abstract/25OPES/25OPES/D021S014R003/673829.3.Belkhir S., Alblooshi Y., Hashmet M.R. Integration of AI for Predicting Water Production and Enhancing Reservoir Management in Naturally Fractured Reservoirs // SPE Advances in Integrated Reservoir Modelling and Field Development Conference and Exhibition; June 2–4, 2025; Abu Dhabi, UAE. Available from: onepetro.org/SPERCSC/proceedings-abstract/25RCSC/25RCSC/D031S017R005/687171.4.Sivrikoz A., Jimenez Chavez M., Buwaiqi S. Tackling High Water Production in Oman South Fields with New Technology // SPE International Heavy Oil Conference and Exhibition; December 10–12, 2018; Kuwait City, Kuwait. Available from: onepetro.org/SPEHOCE/proceedings-abstract/18HOCE/18HOCE/D021S007R004/214693.5.Zhao M., Xin X., Yu G., et al. Mechanistic Study and Optimization of High Water Cut Phase Management Strategies in Fracture-Vuggy Carbonate Reservoirs with Bottom Water // Processes. 2023. Vol. 11, Issue 11. doi: 10.3390/pr11113135.6.Wu W., Hou J., Qu M., et al. Application of Phenolic Resin Crosslinked Polymer Gel in Fractured-Vuggy Carbonate Reservoir with High Temperature and High Salinity // International Petroleum Technology Conference; February 21–23, 2022; Riyadh, Saudi Arabia. Available from: onepetro.org/IPTCONF/proceedings-abstract/22IPTC/22IPTC/D012S110R001/480026.7.Sydansk R.D., Al-Dhafeeri A.M., Xiong Y., Seright R.S. Polymer Gels Formulated with a Combination of High and Low Molecular-Weight Polymers Provide Improved Performance for Water-Shutoff Treatments of Fractured Production Wells // SPE/DOE Symposium on Improved Oil Recovery; April 17–21, 2004; Tulsa, Oklahoma. Available from: onepetro.org/SPEIOR/proceedings-abstract/04IOR/04IOR/SPE-89402-MS/71367.8.Gussenov I., Berzhanova R.Zh., Mukasheva T.D., et al. Exploring Potential of Gellan Gum for Enhanced Oil Recovery // Gels. 2023. Vol. 9, Issue 11. doi: 10.3390/gels9110858.9.Wu Q-H., Ge J-J., Ding L., Zhang G-C. Unlocking the potentials of gel conformance for water shutoff in fractured reservoirs: Favorable attributes of the double network gel for enhancing oil recovery // Petroleum Science. 2023. Vol. 20, Issue 2. P. 1005–1017. doi: 10.1016/j.petsci.2022.10.018.10.Varshney M., Goyal A., Goyal I., et al. Improving Conformance in an Injector Well Using Delayed Crosslink Polymer Gel : A Case Study // SPE Asia Pacific Oil and Gas Conference and Exhibition; October 23–25, 2018; Brisbane, Australia. Available from: onepetro.org/SPEAPOG/proceedings-abstract/18APOG/18APOG/D031S020R004/214057.11.Scaramuzza J.L., Fischetti H., Strappa L., Figliuolo S. Downhole Oil/Water Separation System – Field Pilot – Secondary Recovery Application Project // SPE Latin American and Caribbean Petroleum Engineering Conference; March 25–28, 2001; Buenos Aires, Argentina. Available from: onepetro.org/SPELACP/proceedings-abstract/01LACPEC/01LACPEC/SPE-69408-MS/135334.12.SPE Reservoir Advisory Committee. Reservoir Commentary: Potential Implications of Long-Term Shut-Ins on Reservoir // Journal of Petroleum Technology. 2020. Vol. 72, Issue 07. P. 31–33. doi: 10.2118/0720-0031-JPT.13.Yegane M.M., van Wieren T., Fadili A., et al. Polymer-Assisted-Water-Alternating-Gas for Improving the CO2 Flow Properties in Porous Media // SPE Annual Technical Conference and Exhibition; October 16–18, 2023; San Antonio, Texas, USA. Available from: onepetro.org/SPEATCE/proceedings-abstract/23ATCE/23ATCE/D011S009R003/535551.14.Hu J., Li A. Experimental Investigation of Factors Influencing Remaining Oil Distribution under Water Flooding in a 2-D Visualized Cross-Section Model // ACS Omega. 2021. Vol. 6, Issue 24. P. 15572–15579. doi: 10.1021/acsomega.0c05534.15.Sagyndikov M., Gussenov I., Shakhvorostov A., et al. Downhole Oil-Water Segregation in Production Wells: Review, Design, Simulation and Field Trials // Engineered Science. 2025. Vol. 38. doi: 10.30919/es1866.