非线性渗流对特低渗油藏数值模拟开采的影响

Influence of Nonlinear Seepage on Numerical Simulation Exploitation in Extra-Low Permeability Reservoirs

特低渗油藏的数值模拟技术是近年来诸多科研人员关注的焦点,然而特低渗油藏渗流曲线的非线性段和启动压力梯度对油藏开发动态的作用未被现有的商业化软件考虑。以特低渗油藏非线性渗流数值模拟技术为主要的研究方向,建立了特低渗油藏非线性渗流数值模型。用自制软件模拟研究非线性渗流对特低渗油藏数值模拟开采的影响,比较了达西模型、拟启动压力梯度模型和非线性模型的差异,对方向性、油水相态进行了敏感性分析。模拟结果显示,拟启动压力梯度模型的生产效果最差,在一定程度上夸大了地层阻力;达西模型没有考虑启动压力梯度的存在,减小了地层阻力对渗流的影响;非线性模型中启动压力梯度的存在导致渗流阻力增大,增大了生产压差,降低了生产效果。研究结果为特低渗油藏的流动模拟和高效开采提供了理论方法,对提高特低渗油田的采出效果具有一定的指导意义。

The numerical simulation technology of ultra-low permeability reservoir is the focus of scientific researchers in recent years.However,the nonlinear segment of the seepage curve of low permeability reservoir and the effect of starting pressure gradient on reservoir exploitationare are not considered by commercial software.In this paper,the nonlinear seepage numerical simulation technology of extra-low permeability reservoirs is the main research direction,and the nonlinear seepage numerical model of extra-low permeability reservoirs is established.The self-made software was used to simulate and study the effects of nonlinear seepage on the numerical simulation of extra-low permeability reservoirs.The differences between Darcy model,pressure gradient model and nonlinear seepage model are compared.The sensitivities of the direction and oil-water phase of nonlinear seepage are analyzed.The simulation results show that the production of pressure gradient model is the worst,which exaggerates the formation resistance.The Darcy model does not consider the existence of starting pressure gradientand,and reduces the effect of formation resistance on seepage.The presence of starting pressure gradient in nonlinear model leads to an increase of seepage resistance,which increases production pressure difference and reduces well production.The results provide a theoretical method for the flow simulation and high-efficiency exploitation of extra-low permeability reservoirs,which has certain guiding significance for improving the recovery of extra-low permeability oilfields.