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针对低渗透油藏非线性渗流理论与数值模拟方法方面存在的大量问题,从毛细管模型出发,推导了低渗透油藏非线性渗流新模型,详细解释了新模型中特有的物理参数内涵;并由此建立了低渗透油藏非线性单相渗流理论,与相对渗透率引入“渠道流”假设一致,将单相非线性新模型推广到两相渗流中,建立了能够同时考虑启动压力梯度、非线性渗流弯曲段连续变化的数值模拟方法。根据所建立的低渗透油藏单相稳态和非稳态渗流理论以及数值模拟方法,开展了达西、拟启动压力梯度和非线性模型的油藏动态对比计算。结果表明:低渗透油藏主要受非线性渗流控制,仅井点的少数网格存在拟线性流动,非线性模型计算的结果介于达西和拟启动线性模型之间。
Aiming at a large number of problems in nonlinear seepage theory and numerical simulation of low permeability reservoirs, a new model of nonlinear seepage in low permeability reservoirs is derived from the capillary model, and the connotation of the unique physical parameters in the new model is explained in detail. The established theory of single phase non-linear flow in low permeability reservoirs is consistent with the assumption of relative permeability introduced in “channel flow”. The new single-phase nonlinear model is extended to two-phase seepage flow, , Numerical simulation method of continuous variation of nonlinear seepage bending section. According to the theory of single-phase steady and unsteady seepage and the numerical simulation of low-permeability reservoirs, the dynamic contrast calculation of Darcy, proposed pressure gradient and nonlinear model is carried out. The results show that the low permeability reservoirs are mainly controlled by the nonlinear seepage flow, and the quasi - linear flow is only found in the few grids of the well points. The result of the nonlinear model calculation is between that of Darcy and the quasi - start linear model.