考虑应力敏感影响的气井产能分析新方法

A new method for gas well productivity analysis considering stress sensitivity

低渗气井回压试井测试时,地层未达到稳定流动而录取井底流压资料,会导致采用常规二项式产能方程求取产能误差较大,甚至无法求取。从渗流理论出发,通过引入渗透率应力敏感表达式,建立了适用于异常高压低渗气藏的气井不稳定产能方程;针对回压试井测试,提出了考虑应力敏感影响的气井产能分析方法。在莺歌海盆地M7井,应用该方法能够较好地回归出产能分析曲线,求得该井无阻流量84.1×10^4 m^3/d,与“一点法”计算结果基本一致。经过对比分析,考虑应力敏感后计算的产能减少19%。可见,应力敏感对异常高压低渗气井产能的影响不容忽视。该方法为异常高压低渗气藏不稳定产能测试资料的处理提供了有益的借鉴。

During back pressure test in low permeability gas wells,the productivity calculated by conventional binomial productivity equation will have a large error,or even cannot be obtained if the bottom-hole flow pressure data is collected under an unstable flow,.Based on the flow theory in porous media,an unsteady productivity equation of gas well is established,which is applicable to abnormal high pressure and low permeability gas reservoir,by introducing the permeability stress sensitivity expression.For back pressure well testing,a method of gas well productivity analysis considering stress sensitivity is presented in this paper.This method was applied to Well M7 in Yinggehai Basin and a better regression analysis curve was obtained.The absolute open flow potential obtained of this well is 84.1×10^4 m^3/d,which is basically consistent with the calculation result of"single-point method".After comparative analysis,the calculated productivity was reduced by 19%after considering the stress sensitivity.It can be seen that the influence of stress sensitivity on the productivity of abnormal high pressure and low permeability gas wells cannot be ignored.This method provides a useful reference for processing unstable productivity testing data in abnormal high pressure and low permeability gas reservoirs.