压敏性多重介质气藏压裂水平井渗流特征

Flow characteristics of fractured horizontal wells in pressure-sensitive multi-media gas reservoirs

超高压、异常高压气藏气井生产压降容易引起强的压敏效应,为研究压敏性多重介质气藏压裂水平井渗流特征,建立了压敏性多重介质气藏多段压裂水平井渗流模型。采用点源函数、摄动法、Laplace变换法、Fourier积分变换法得到拉式空间下不稳定压力解,进而采用Duhamel原理与Stehfest数值反演求得了实空间下井底压力,绘制了试井双对数理论图版。研究表明:应力敏感会增大晚期渗流阶段的压降反应,表现为试井双对数曲线末端上翘;随窜流系数增大,多重介质气藏中窜流段越早发生,压力导数曲线上窜流凹子越往左移;人工裂缝条数越多、角度越小、半长越大,压力导数曲线越往下移。采用新建立的压敏性多重介质气藏渗流模型,结合实测压力恢复数据,拟合解释了实际储层参数及渗流特征,并验证了模型的准确性。

In the context of high-pressure and abnormally high-pressure gas reservoirs,the production pressure drop in gas wells can easily induce a strong pressure-sensitive effect.To investigate the flow characteristics of fractured horizontal wells in pressuresensitive multi-media gas reservoirs,a comprehensive flow model for multi-stage fractured horizontal wells in pressure-sensitive multi-media gas reservoirs was established.By utilizing point source functions,perturbation methods,Laplace transforms and Fourier integral transforms,the analytical solution for unstable pressure in Laplace space was derived.Subsequently,by employing the Duhamel principle and Stehfest numerical inversion,the bottomhole pressure in real space was obtained,and the log-log theoretical diagram for well testing was plotted.The research shows that stress sensitivity amplifies pressure drop responses during the late flow stages,manifested as an upturn at the end of the log-log well testing curve.As the channeling coefficient increases,the earlier the channeling segment occurs in the multi-media gas reservoir,the more the channeling concavity on the pressure derivative curve moves to the left.The more the artificial fractures,the smaller the angle,the larger the half-length,and the further the pressure derivative curve moves downward.The newly established flow model for pressure-sensitive multi-media gas reservoirs,when combined with actual pressure recovery data,successfully fits and interprets the reservoir parameters and flow characteristics,which versa validates the accuracy of the model.