Petroleum Science >2023,??Issue2:??- DOI: https://doi.org/10.1016/j.petsci.2022.11.012
Polymer efficiency and sulfate concentration for hybrid EOR application to an acidic carbonate reservoir Open?Access
文章信息
作者：Yeonkyeong Lee, Wonmo Sung, Jihoon Wang
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引用方式：Yeonkyeong Lee, Wonmo Sung, Jihoon Wang, Polymer efficiency and sulfate concentration for hybrid EOR application to an acidic carbonate reservoir, Petroleum Science, Volume 20, Issue 2, 2023, Pages 993-1004, https://doi.org/10.1016/j.petsci.2022.11.012.
文章摘要
Abstract: 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.
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Keywords: Polymer efficiency; Low-salinity polymer flooding; Polymer adsorption; Wettability alteration; Sulfate ion; Acidic carbonate reservoir