致密气藏间歇生产井工作制度优化新方法

A new method for optimizing the working system of intermittent gas wells in tight gas reservoirs

致密气藏间歇气井在生产过程中难以准确制定合理的工作制度,导致部分间歇气井利用率低、气井生命周期缩短。基于气井间歇生产机理与压力恢复特征,建立了间歇生产井工作制度优化新方法。通过计算压力导数与传播半径曲线,在曲线出现拐点前后作外切直线,取两条外切直线的交点为最优压力恢复时间点。以苏里格气田为研究对象,利用新方法对三种类型间歇生产井最优压力恢复时间进行计算。结果表明,井筒积液类间歇生产井以10 d作为最优压力恢复时间;压力偏低类间歇生产井以20 d作为最优压力恢复时间;生产末期类间歇生产井Ⅰ、Ⅱ和Ⅲ类井分别以20 d、40 d和60 d作为最优压力恢复时间。该方法为致密气藏间歇生产井工作制度优化和气井精细化管理提供有效的理论和技术支撑。

The rational open/shut-in time of intermittent gas well in tight gas reservoir during production is difficult to define accurately,which results in low utilization rate and short lifecycle of some intermittent gas wells.Based on the principle of seepage mechanics,together with the pressure build-up and production behaviors of intermittent gas wells,the relationship between the pressure propagation distance of intermittent production gas well and time was established.According to the curve of pressure derivative and propagation radius,a circumscribed straight line was drawn before and after the inflection point of the curve,and the intersection of the two circumscribed straight lines was taken as the optimal build-up time point.Thus,a new method for optimizing the working system of intermittent gas wells in tight gas reservoirs was obtained.Taking the Sulige gas field as the research object,the new method was used to calculate the optimal build-up time of three types of intermittent gas wells.The results show that the optimal build-up time is 10 d for intermittent gas wells with liquid load,20 d for intermittent gas wells with low pressure,and 20 d,40 d and 60 d respectively for ClassesⅠ,ⅡandⅢintermittent gas wells at the end of production.The new method provides an effective theoretical and technical support to the optimization of the working system of intermittent gas wells in tight gas reservoirs and the refined management of gas wells.