Study on Effect of Polymer and Sulfate Concentration on Enhanced Recovery in Changqing Oilfield
Polymer drive plays an important role in hybrid enhanced recovery(EOR).The polymer of low mineralization polymer drive(LSPF)is very sensitive to brine pH.In this study,the effects of different salinity and SO42-mass concentration in sour carbonate reservoirs were experimentally investigated.The results showed that the lower the mineralization,the better the polymer stability,the less polymer adsorption,the greater the change in wettability,and the higher the final recovery.However,the injected fluid did not contain sufficient amount of sulfate ions(SO42-),and the low salinity may not be suitable for LSPF.The polymer efficiency analysis showed that higher oil production could be obtained by adjusting the mass concentration of SO42-under the same condition of polymer mass concentration.
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