高压低渗砂岩油藏储层驱替特征及影响因素

Displacement characteristics and influencing factors in deep section high pressure and low-permeability sandstone reservoir

利用室内水驱油、氮气驱油驱替实验,对东濮凹陷深层高压低渗砂岩油藏驱替特征及影响因素进行研究。研究结果表明:随物性变好,两相共渗区变宽,驱替效果变好。水驱中相对渗透率曲线交叉点分布相对集中,气驱中气相相对渗透率曲线发散。气驱与水驱效果对比,特低渗储层气驱效果好,低渗及低渗以上储层水驱效果好。影响驱替特征的主要因素有驱替速度、净覆压力、两相启动压力梯度、储层物性。特低渗储层存在一最佳驱替速度,驱替时要求净覆压力尽可能小。水驱或气驱中驱油效率不会大幅度提高。气驱与水驱相比,其驱替特征的差异在于流度比、润湿性、储层微观孔隙结构及气、液渗流规律等的差异。

The displacement characteristics and influencing factors of deep section high pressure and low-permeability sandstone reservoir in Dongpu Sag were analyzed with the water and N2 flooding experiment. The result shows that the better the permeability, the wider the two-phase region, and the better the displacement effect. The distribution of the two-phase point of intersection is relatively focused in water flooding experiment, and the distribution of relative permeability curves of gas phase is relatively emanative. The effect of gas flooding in ultra-low permeability reservoir is better, while that of water flooding is better in low permeability reservoir. The factors that affect displacement characteristics mainly include displacement rate, effective overburden pressure, start-up pressure gradient of two phases, and reservoir properties. There is a prime displacement rate in ultra-low permeability reservoir. The effective overburden pressure should be minimal in displacement. The oil displacement efficiency can not be largely improved. The differences of displacement characteristics between N2 flooding and water flooding lie in the differences of mobility ratio, wettability, micro-pore structure and the seepage law.