中文摘要：

致密砂岩油藏水驱渗流特征体现非线性渗流规律,存在启动压力梯度,且水驱过程中多孔介质会产生变形,岩石渗透率降低。通过电镜扫描试验研究致密砂岩纳米级微观孔隙特征,结合岩石颗粒分布特征,建立致密砂岩变形引起应力敏感理论模型,得到岩石介质变形系数,并与试验测试结果进行对比分析;建立考虑致密砂岩岩石变形影响的渗流数学模型,研究启动压力梯度及介质变形共同作用对油、水两相非线性渗流特征影响。算例结果表明,启动压力梯度与介质变形的耦合作用造成水驱渗流阻力增大,地层压降损失增大;介质变形系数越大,相同生产时间内原油采出程度越低,随着生产时间增加,地层压降损失幅度增大。

英文摘要：

The process of water flooding met the law of non-Darcy flow and existed threshold pressure gradient in tight sandstone reservoirs. Porous medium would get deformed,and the permeability would decrease. The nanometer pore characteristics of tight sandstone through scanning electron microscope(SEM) experiment were researched. Based on the distribution of rock particles,a theory model which characterized stress sensitivity caused by medium deformation was established and medium deformation coefficient was derived. The comparison analysis of results between the theory model and experiment is performed. Moreover,a seepage mathematical model was established which took the deformation of tight sandstone into consideration. The coupling influences of the threshold pressure gradient and medium deformation on the oil-water two-phase nonlinear percolation feature are studied. The result shows that the flow resistance and formation pressure drawdown loss increase under the coupling effects of threshold pressure gradient and medium deformation. Moreover,with the increase of production duration,amplitude of pressure drawdown loss would increase.