CO2/原油的混相与混相驱问题探讨

Miscible and Miscible Flooding of CO/Oil

针对在CO2/原油的混相与混相驱认识中存在的问题,以细管实验为基本研究手段,深入分析并阐明了注CO2开发混相和混相驱的机理和存在性问题。研究认为:以最小混相压力为拐点,采收率随注入压力的升高先是呈线性急剧增加,而后增幅越来越小,最终采收率在91%以上,采收率的这种变化规律是注入压力对开发效果的影响,而不是混相与否对开发效果的影响;混相流体是溶解作用和萃取作用共同作用的结果,由于实际开发中存在组分分异和固相沉积作用,多孔介质中不存在真正的完全混相;高于最小混相压力的注CO2开发机理是萃取作用程度极强的非混相开发,注入压力升高更有利发挥萃取作用;在注CO2开发的各阶段,都不存在"驱"的形式,将混相开发称为混相驱有失偏颇。研究成果厘清了关于混相问题的认识,丰富和发展了注气开发技术体系,为注气开发的现场实施提供重要的技术参考。

In view of the problems existing about miscible and miscible flooding of CO2/crude oil,the mechanism and existing problems of miscible and miscible flooding by CO2 injection are analyzed and clarified by means of thin tube experiment.Study shows that the recovery increases sharply with increasing of injection pressure,taking the minimum miscible pressure as the inflection point,then increases less and less,and the final recovery is more than 91.%,the change rule of oil recovery is not the influence of miscibility on development effect,but the influence of injection pressure on development effect,miscible fluid is the result of the joint action of dissolution and extraction,because there exist component differences and solid-phase deposition in actual development,there is no real complete miscibility in porous media.CO2 injection development machine with higher than minimum miscibility pressure is nonmiscible development with a strong degree of extraction.The higher the injection pressure,the stronger the extraction.In all stages of CO2 injection development,there is not exist"flooding",so it is biased to call miscible development miscible flooding.The research results clarify the understanding of the problem of miscibility,enrich and develop the technical system of gas injection development,while provide important technical reference for the field implementation of gas injection development.