低渗透压敏油藏油井流入动态方程及其应用

注水开发的低渗透油藏存在启动压力和压力敏感性,使开发难度加大。当流压低于饱和压力以后,流入动态指示曲线凹向压力轴,会出现一个产量最大点。在前人研究的基础上,从平面径向拟稳态渗流规律出发,考虑启动压力梯度和压力敏感效应对油藏渗流的影响,与油相和液相相对流动能力方程相结合,建立了具有最大产量点的低渗透压力敏感油藏直井流入动态方程,据此可对油藏产能进行评价预测,确定出油井最低允许流动压力和油井的合理工作制度。在龙南、新站油田的应用表明,预测值与实测值比较吻合,满足矿场工程精度要求,说明所建立的流入动态方程能有效评价预测油井产能和确定油井允许的最小流压界限,为充分发挥油井生产能力、合理高效开发低渗透压力敏感油藏提供了理论依据。

In-flow Equation and Its Application for Low-Permeability and Pressure-Sensitive Oil Reservoirs

It is very difficult to develop low-permeability reservoirs with water injection due to the threshold pressure and pressure sensitivity.When the flowing pressure is lower than the saturation pressure,the inflow performance curve concave to the pressure axial causing a maximum flow rate point.Based on the previous studies and radial fluid pseudosteady state porous flow,a IPR equation with maximum flow rate point for low permeability and pressure sensitivity reservoirs was developed,considering the impacts of threshold pressure gradient and pressure sensitivity effects on reservoir porous flow.The reservoir productivity can be evaluated to determine the maximum flowing pressure and reasonable flowing conditions.The application in Longnan and Xinzhan oilfields indicate that the predicted value agrees with the measured which satisfies the requirement of filed application.It shows that the proposed IPR equation can effectively evaluate the well productivity and determine the allowed minimum flowing pressure and provided the theoretical basis for reasonably developing the low-permeability and pressure-sensitive reservoirs.