Effects of crude oil composition on interfacial activity and recovery efficiency of ASP flooding in Daqing oilfield in China

摘要

To evaluate the reservoir adaptability of a strong-alkali ternary compound system, field trials of alkaline/surfactant/polymer (ASP) flooding has been carried out in Lamadian, Saertu and Xingshugang oilfields in Daqing, China. The crude oil compositions have significant effects on retention time of ASP fluid and on chemicals concentrations in produced fluid. Here, to investigate the effects of crude oil compositions on enhanced oil recovery (EOR) of ASP flooding, we studied the crude oil compositions in the three oilfields and the interaction between crude oils and the strong-alkali ternary compound system in laboratory. We find that the great differences in contents and structures of crude-oil compositions more severely affect the interfacial tension (IFT). In the three oilfields, higher contents of high-carbon normal alkane and aromatics lead to the lower contents of polar compounds comprised of O, S and N, and the longer chain organic acid reduces the emulsified ability of Lamadian crude oil. The Lamadian crude oil shows higher IFTs between the ASP fluid and active components, raffinate, and crude oil compared with other two oilfields. Also, differences in contents and structures of crude oil components aggravate the chromatographic separation of ASP fluid and reduce recovery efficiency, especially in the Lamadian oilfield.