水平气井试井分析新方法

水平气井渗流机理复杂,对不稳定试井资料难以分析。根据以上特点,建立了水平方向无限延伸情形下水平气井的试井分析数学模型。利用拉氏反演算法,作出了识别和求取流动阶段地层参数的试井分析典型曲线。从压力导数曲线看出,水平气井压力动态出现4个明显的特征段,即纯井筒储集阶段、早期垂向径向流阶段、早期线性流阶段和晚期水平径向流阶段。利用这4个特征段压力导数曲线的特征直线,推导出求取气藏水平渗透率、垂向渗透率、表皮系数及原始地层压力的表达式,从而建立起水平气井试井分析的特征值方法。用实例论证了该方法的可靠性。

A new method for well test analysis of horizontal gas well

The seepage flow mechanism in horizontal gas well is complicated, and the analysis of test data from the transient well is also difficult. A mathematical model was established for well test analysis of horizontal gas well with boundless horizontal extension. The typical curves of well test analysis were plotted by Stehfest inversion algorithm to distinguish different flow stages and obtain reservoir parameters. There are four obvious stages on the pressure derivative curve, including pure well bore storage stage, early vertical radial flow stage, early linear flow stage and late horizontal radial flow stage. The characteristic lines manifested by derivative curve with four stages were used to derive the formulas of horizontal permeability, vertical permeability, skin factor and initial reservoir pressure. The characteristic value method for the well test analysis of horizontal gas well was proposed and verified by an exact case.