束缚水饱和度、岩石性质对自吸的影响

EFFECT OF INITIAL WATER SATURATION AND ROCK LITHOLOGY ON SPONTANEOUS IMBIBITION

自吸是裂缝性油藏采油的一个特别重要的方面。影响自吸的因素有很多，文中主要研究束缚水饱和度和岩石性质 对自吸速度及采收率的影响。研究中使用的多孔介质分别为高渗砂岩、低渗砂岩、石灰岩。结果表明，束缚水饱和度对砂岩 体系自吸速度有较强的影响．当束缚水饱和度Ｓｗｉ小于 ６％时，自吸速度随Ｓｗｉ增加而减小，在Ｓｗｉ为 ６％～１５％的范围内自 吸速度达最低，当Ｓｗｉ在１５％～３０％的范围内，自吸速度随束缚水饱和度增高而升高。在束缚水饱和度为零的情况下，三种 类型岩石中以石灰岩的自吸采收率最高，其值比同等渗透率级别的砂岩高２３％。

Spontaneous imbibition is of special importance to the efficiency of oil recovery from fractured reservoirs. Many factors affect the process of spontaneous imbibition. This paper is focused on the effect of initial water saturation and rock lithology on rate of imbibition and oil recovery. The porous media used in this study are high permeability sandstone,low permeability sandstone and chalk. Results show that initial water saturation Swi has a strong effect on rate of imbibition of sandstone system. For Swi <6%,imbibition rate decreases with increase in Swi. In this range of Swi, 6%-15 %,the rate of imbibition is at a minimum. For 30%>Swi>15 %,imbibition rate increases with increase in Swi Among three types of rocks,at zero initial water saturation,imbi- bibition recovery from chalk samples is the highest,about 23% higher than that from sandstone with similar permeability.