Polymer efficiency and sulfate concentration for hybrid EOR application to an acidic carbonate reservoir

作     者：Yeonkyeong Lee Wonmo Sung Jihoon Wang 

作者机构：Korea Institute of Geoscience and Mineral Resources124 Gwahak-roYuseong-guDaejeon34132Republic of Korea Department of Earth Resources and Environmental EngineeringHanyang University222 Wangsimni-roSeongdong-guSeoul04763Republic of Korea 

出 版 物：《Petroleum Science》 (石油科学（英文版）)

年 卷 期：2023年第20卷第2期

页      面：993-1004页

核心收录：

学科分类：0820[工学-石油与天然气工程] 08[工学] 082002[工学-油气田开发工程] 

基　　金：supported by the Energy Efficiency&Resources(No.20212010200010) the“Development of Intelligential Diagnosis,Abandonment Process and Management Technology for Decrepit Oil and Gas Wells”(No.20216110100010)of the Korea Institute of Energy Technology Evaluation Planning(KETEP)grant funded by the Korean Government Ministry of Trade,Industry&Energy. 

主　　题：Polymer efficiency Low-salinity polymer flooding Polymer adsorption Wettability alteration Sulfate ion Acidic carbonate reservoir 

摘      要：Polymers play an important role in hybrid enhanced oil recovery (EOR), which involves both a polymer and low-salinity water. Because the polymer commonly used for low-salinity polymer flooding (LSPF) is strongly sensitive to brine pH, its efficiency can deteriorate in carbonate reservoirs containing highly acidic formation water. In this study, polymer efficiency in an acidic carbonate reservoir was investigated experimentally for different salinity levels and SO42− concentrations. Results indicated that lowering salinity improved polymer stability, resulting in less polymer adsorption, greater wettability alteration, and ultimately, higher oil recovery. However, low salinity may not be desirable for LSPF if the injected fluid does not contain a sufficient number of sulfate (SO42−) ions. Analysis of polymer efficiency showed that more oil can be produced with the same polymer concentration by adjusting the SO42− content. Therefore, when river water, which is relatively easily available in onshore fields, is designed to be injected into an acidic carbonate reservoir, the LSPF method proposed in this study can be a reliable and environmentally friendly method with addition of a sufficient number of SO42− ions to river water.