储层条件下超临界二氧化碳与原油体系最小混相压力研究

摘要

注二氧化碳开采原油已经成为目前世界范围内特低或超低渗透油田重点采用的提高原油采收率技术,驱油过程中较为理想的驱替形态就是能够形成二氧化碳混相驱,而最小混相压力是形成混相驱关键因素之一,因此快速准确预测最小混相压力是实现混相驱的重要环节.通过长细管驱替实验法和多种经验公式法对储层条件下超临界二氧化碳与试验区原油体系最小混相压力的预测进行了研究,并用长细管驱替实验法对各经验公式法测定的结果进行了误差分析.研究结果表明:长细管驱替实验法预测的最小混相压力为29.15 MPa;各经验公式法计算得到的最小混相压力相差较大,预测最大值为42.60 MPa,最小值为10.34 MPa,平均值为26.83 MPa;对比长细管驱替实验法测得的结果,各经验公式法预测的最小混相压力平均值的相对误差为7.96%,其中相对误差最小的是石油采收率研究所提出的PRIⅠ方法,相对误差为1.26%.%Developing oil by inj ecting carbon dioxide has become the important enhanced oil recovery technology for the ultra-low permeability oil field and extra-low permeability oil field in the current world.The ideal displacement is to form carbon dioxide miscible flooding in the process of oil displacement.The minimum miscible pressure is one of the key factors to form miscible flooding.So it is an important part of the realization of miscible flooding to predict the minimum miscible pressure quickly and accurately.The minimum miscible pressure prediction of the supercritical carbon dioxide and crude oil system under reservoir condition of the test area is studied through the long slim tube displacement experiment method and a variety of empirical formula methods.The minimum miscible pressure predicted by the long slim tube displacement experiment method is applied to analyze the relative error of the result of the empirical formula methods.The research results show that the minimum miscible pressure predicted by the long slim tube displacement experiment method is 29.15 MPa;the minimum miscible pressure values calculated by the various empirical formula methods are quite different:the maximum is 42.60 MPa,the minimum is 10.34 MPa,and the average value is 26.83 MPa;the average relative error to the long slim tube displacement experiment method is 7.96%.The relative error of PRIⅠ method proposed by Petroleum Recovery Institute is 1.26%, which is the smallest relative error among all of the empirical formula methods.