三相相对渗透率曲线实验测定

建立CT双能同步扫描实验方法,结合稳态物理模拟方法对油湿和水湿露头砂岩的油气水三相相对渗透率进行实验测定,同时考察不同饱和历程对相对渗透率曲线的影响.CT双能同步扫描法可准确获取三相流体饱和度并消除末端效应的影响,将实验测得相关数据代入达西公式可算得不同饱和度下各相的相对渗透率.研究结果表明,对水湿岩心,水的等渗线为一系列直线,表明水相相对渗透率只与含水饱和度有关；油的等渗线为一系列凹向含油饱和度顶点的曲线,气的等渗线为一系列凸向含气饱和度顶点的曲线,表明油相和气相的相对渗透率与三相饱和度都有关；而在油湿岩心中,油气水三相的等渗线都是一系列凸向各自饱和度顶点的曲线,表明油气水的相对渗透率与三相流体饱和度都有关.不同饱和历程对润湿相的等渗线影响不大,但对非润湿相的等渗线有影响,两种饱和历程下非润湿相等渗线形态基本相同但位置不同.

Measurement of three-phase relative permeabilities

Three-phase relative permeabilities of water-wet and oil-wet outcrops with two saturating histories (DDI and IID) are investigated by steady physical simulation experiments. CT Dual Energy Simultaneous Scanning (DESS) method was introduced to measure three-phase saturations accurately, which can eliminate the end effect. The relative permeability of each phase at a given saturation is calculated by Darcy law. The experiment results clearly show that for water-wet cores, the isoperms of water are straight lines, which means that the relative permeability of water depends on water saturation only. The isoperms of oil are curves concave towards 100% oil saturation point, and the isoperms of gas are curves convex towards 100% gas saturation point, which means that the relative permeabilities of oil and gas depend on all the three phase saturations. For oil-wet cores, all the isoperms of water, oil and gas are curves convex towards their 100% saturation points, which means that the relative permeabilities of water, oil and gas depend on all the three phase saturations. In addition, the isoperms of wetting phase are similar for the two saturation histories, while those of non-wetting phases are quite different. Though the isoperms are the same in shape, they are different in values and positions.