水平气井产量递减分析方法研究

Production decline art analysis for horizontal gas wells

为了得到一种评价水平气井工作效率和储层参数的方法,讨论了圆形封闭地层三维不稳态情形的水平气井产能动态.通过引入拟压力,拟时间函数,利用Duhamel褶积和数值反演得到了水平气井McCray型产量积分平均递减图版及导数图版,结合实例给出了图版拟合的步骤和方法.结果表明:McCray型产量积分平均递减可以分为两个阶段,第1阶段为不稳态递减阶段,其递减曲线发散,第2阶段为拟稳态递减阶段,其递减曲线归一,与Arps调和递减曲线吻合.生产实例显示:理论图版与实际数据点的拟合率相对误差在1%～2%之间,符合工程精度要求,利用该方法可以预测储层有效渗透率、泄流面积、泄流孔隙体积、等效泄流半径、储层表皮因子、初始递减产量以及初始递减率等参数.

The production behavior of in order to obtain the method of both transient 3D flows in a bounded reservoir was described evaluating work efficiency of gas wells and key reservoir parameters. Based on Duhamel convolution and numerical inversion, the type curves of McCray integral-average production declined and its derivative for horizontal gas wells was presented by employing the pseudo-pressure and pseudo-time functions. A field example was performed to illustrate the procedure of type-curve matching. The results show that McCray type curves can be divided into two parts where they were scattered in the early transient period and drawn to Arps harmonious decline in the late pseudo-steady period. In the example, 1%--2% relative error of type-curve matching between the theoretical curve and practical data agrees with engi- neering precision bounds. The key parameters including effective permeability, drainage area, drainage porous volume, drainage effective radius, skin factor, initial decline production and initial decline factor can successfully be evaluated using the type curve matching method.