低渗透气藏气井产能评价新方法

目前我国发现的气藏大都是低渗透气藏，这类气藏的渗流规律不同于常规气藏渗流规律，如果按常规气藏的产能评价方法对产能测试资料进行分析评价，将得出错误的结果。为此，从渗流基本定律出发，根据低渗透气藏气体渗流过程中存在启动压力梯度的特点，推导出了低渗透气藏气井产能方程的新形式，该新的产能方程有别于传统的二项式方程，是一个三项式渗流方程，这就解释了为什么在低渗透气井中用常数的二项式或指数式方程来整理气井产能测试资料将导致错误解释结果的原因。根据新方程的特点，采用最优化方法进行整理，并将该理论用于西部某气田气井产能的评价，取得了很好的结果

A NEW METHOD FOR DELIVERABILITY ANALYSIS OF GAS WELLS IN LOW-PERMEABILITY RESERVOIRS

So far,most gas reservoirs discovered in China belong to low-permeability reservoirs,in which fluids have different flowing mechanism from that in conventional gas reservoirs.Considerable error will result from application of conventional methods to analyze productivity of wells in such reservoirs.Therefore,a new expression of deliverability equation for gas wells in low-permeability reservoirs were inferred here on the basis of basic fluid flow mechanism and with consideration of the start-up pressure gradient for fluid flow in such reservoirs.Different from traditional binomial equation,this deliverability equation is trinomial one,which is also helpful to explain the error of deliverability analyzed by a binomial equation with a constant term or an exponential equation.Satisfying results have been acquired when using the new equation,by the optimization method,in a gas field of West China to analyze the deliverability of gas wells.