胜利油区水驱普通稠油油藏注蒸汽提高采收率研究与实践

胜利油区地层条件下原油黏度大于100mPa.s的普通稠油油藏水驱采收率一般低于18%,普通稠油油藏采收率低于25%的储量达到3.75亿t。稠油为非牛顿流体,渗流所需剪切应力大;压力梯度相同,油越稠渗流速度越低;常温驱油效率低,水驱波及系数小,且水驱后原油黏度增加。稠油加热后渗流速度大幅度增加,启动压力梯度减小,油水相对渗透率得到改善,驱油效率大幅增长。因此,注蒸汽热采可以改善稠油渗流特性,降低残余油饱和度,提高驱油效率、波及系数及采收率。为进一步提高水驱后普通稠油油藏的采收率,在优化注蒸汽开发技术政策的基础上,在孤岛油田开展了先导试验,明显提高了采收率。图10表3参23

Studies and practices on the steam injection EOR of water drived heavy oil reservoirs in Shengli petroliferous province

The water drive recovery efficiency of the ordinary heavy oil reservoirs with crude viscosity of more than 100mPa·s is generally lower than 18% in Shengli petroliferous province. The reserves with recovery factors of less than 25% are up to 375 million tons. Under the same pressure gradient, the higher the oil viscosity is, the lower the percolation flow velocity. At normal temperatures, the oil driving efficiency and the sweep efficiency of water driving are low, and the crude viscosity increases after water drive. When heavy oil is heated, its percolation flow velocity increases considerably, the starting pressure gradient decreases, the oil-water relative permeability improves, and the oil displacement efficiency increases. The steam flood can improve heavy oil seepage flow characteristics, remain oil saturation, and enhance oil displacement efficiency, conformance factor as well as EOR. For further improving the ordinary heavy oil reservoirs recovery, a pilot test was carried out based on optimizing the development technique policy of steam injection and obtained an obvious EOR result