ASP体系在大庆二类油层中的色谱分离现象及其对采收率的影响

Chromatographic Separation of ASP System and Its Effect on Recovery in Daqing Second-Class Oil Layer

ASP体系在二类油层中运移不同距离时,体系的黏度和及其与原油间的界面张力等均会发生变化。本实验采用不同长度的人造岩心(10、20、30、60和80 cm)来模拟ASP体系在油藏中的运移距离,通过测定各组实验产出液的黏度及其与原油间界面张力,分析ASP体系运移不同距离时体系性能的变化及其对采收率的影响。实验结果表明,随着ASP驱油剂运移距离的增大,复合驱采收率逐渐降低,且在近井地带附近采收率降低的幅度较大。复合驱采收率受复合体系的黏度和其与原油界面张力影响,在0~30 cm运移范围内,由于超低界面张力和较强流度控制能力的综合作用,驱油剂在油藏中的波及体积和驱油效率较大,复合驱采收率和最终采收率较高;当运移距离大于30 cm时,由于界面张力值迅速升高,其对采收率的贡献较小,此时体系的黏度在驱油过程中起着主导作用;复合驱采收率随着驱油剂相对注入量的增大而增加,适当地增大ASP驱油剂的相对注入量可有效的提高大庆二类油层的采收率。

The viscosity of ASP system and the interfacial tension between ASP system and the crude oil can be changed when the ASP agent flows through the Secondary-Class oil layer. In this paper,five different length of artificial cores(10,20,30,60,80 cm)were used to simulate the different ASP migration distances. The viscosity of the production fluid and the interfacial tension between the production fluid and the simulated oil were measured in order to analysis the effect of the change of ASP agent properties on recovery. The result showed that as the migration distance increasing,the ASP flooding recovery decreased gradually and the decreasing range of the recovery was larger nearby the injection end. The ASP flooding recovery was affected by the viscosity and the interfacial tension. When the migration distance was smaller than 30 cm,the displacement efficient and sweep efficient were relative higher because of the low interfacial tension and strong mobility control ability,leading to higher flooding recovery and ultimate recovery;however,when the migration distance was larger than 30 cm,the viscosity played the dominant role in the ASP flooding process and the effect of the interfacial tension was weak. The ASP flooding recovery increased with the increase of relative injection volume. Therefore,the increase of the relative injection volume of the ASP flooding adequately could enhance the recovery of Daqing second-class oil layer effectively.