低饱和度油藏原始饱和度计算及含水上升规律

The initial oil saturation calculation and water cut rising rules of low oil saturation reservoir

受低幅度构造、地层倾角小、储层渗透率低、油源供给不足等因素影响,油层中存在自由水,若整个开发层系的油层大面积内均为油水同层,则称为低含油饱和度油藏。低含油饱和度油藏油井投产初期就具有一定含水率。由于室内岩心试验获得的油水相对渗透率曲线是在饱和油情况下进行,因此,油田实际含水与采出程度和利用室内试验曲线计算出的理论含水与采出程度曲线不能较好吻合,当油藏原始含水饱和度较高时这种误差会很大,导致含水与采出程度理论曲线无法正确预测油藏含水上升规律。根据试验获得的相渗曲线和实际生产数据,采用试验数据与生产实际相互印证的方法,修正油藏含水上升规律,计算油藏原始含水饱和度,解决了油藏原始含油饱和度计算以及具有原始含水饱和度油藏含水上升规律预测问题,对正确认识油藏和开发指标预测具有重要意义。

Under the influence of low amplitude structures, low formation dip, low reservoir permeability, insufficient supply of oil sources and other factors, there is free water in the reservoir. If large areas of the reservoir in the entire layer series of development are oil-water layers, it is a low oil saturation reservoir. Reservoir wells have certain water cut during the initial production in low oil satura- tion reservoir. Oil-water relative permeability curves are obtained from indoor core tests in the case of the saturated oil, therefore, the actual water cut and degree of reserve recovery which was calculated through indoor tests can＇ t match well. And the error will be very large with higher initial water saturation, which makes the theoretic curve of water cut and degree of reserve recovery unable to predict water cut rising rules correctly. Taking the method of confirming experimental data and actual production by each other, based on the relative permeability curves obtained by experiments and data from actual production, this paper revises the laws of water cut rising, calculates the initial water saturation, and solves the problems of the calculation of the initial oil saturation and the prediction of water cut rising rules in a reservoir with initial water saturation, which is of great importance to a correct understanding of reservoir and the prediction of development index.