低渗透异常高压气藏典型井的数值模拟

Numerical simulation on low permeability and abnormal high pressure gas reservoirs

低渗透异常高压气藏是一类特殊的气藏,气体渗流除滑脱效应外,还要受到启动压力梯度、介质变形等因素的影响,从而导致气体在储层中的渗流为偏离达西规律的非线性流动。到目前为止还没有一套可靠的描述该类气藏动态预测的模型和方法,运用常规的气藏工程手段和气藏模拟技术往往难以正确认识其开发规律,导致开发效果不理想。在分析了启动压力梯度、介质变形对低渗透异常高压气藏渗流影响的基础上,建立了针对低渗透异常高压气藏的三维气、水两相非线性渗流数学模型。该模型还考虑了多种非线性渗流对气藏开发动态的影响。利用该模型对四川某低渗透异常高压气藏的典型井进行了生产历史拟合及模拟预测方案设计,为该气藏设计了一套开发首选方案。该研究实现了对低渗透异常高压气藏开发的定量动态预测,对气藏的高效开发具有指导意义。

The low permeability and abnormal high pressure gas reservoirs is a particular type of gas reservoirs with the gas in a state of nonlinear and non-Darcy flow caused not only by slippage effect but by the start-up differential pressure and the deformation of medium. Up till now, there is still not any reliable modeling and methods on dynamic prediction of this kind of gas reservoir so its development has a bad result for lack of a full knowledge of its discipline by use of regular technology and methods. Based on analysis on the effect of the start-up differential pressure and the deformation of medium, this paper built up a mathematical 3D model on gas/water two-phase nonlinear flow especially for this type of gas reservoir with full consideration of many different kinds of nonlinear flow. Through a case study on this model conducted in typical wells of a certain low permeability and abnormal high pressure gas reservoir, the Sichuan basin, a package of development plans as the first choice was projected for an individual well based on the simulation of production history and performance prediction. This study provides reference for highly efficient development of such reservoirs by performance prediction in quantitative and dynamic way.