煤层气井关井井底压力恢复模型

为了准确拟合煤层气井关井井底压力变化,基于煤层流体渗流规律和流体稳定流动能量方程,依据煤层气井情况分阶段建立了井底压力恢复模型。依据韩城WL1井地层参数,得到了关井时井底压力动态变化规律。结果表明:井底压力恢复双对数曲线中气水两相流阶段和单相水流动阶段斜率不同,分别为0.3919和0.0682,其后期曲线趋于水平,类似于压裂井二开二关压力恢复试井双对数曲线。随着井底压力的恢复,储层渗透率和解吸半径逐渐减少。当井底压力由1.1MPa恢复到2.36MPa时,解吸半径由11.97m减少到4.46m,产气量由3200m3/d减少到444.25m3/d。

Model of Mine Bottom Pressure Recovery in CBM Mine Closing

In order to correctly simulate pressure variation in CBM mine closure,applying flow seepage rule and fluid stable flow energy equation,model of mine bottom pressure recovery was set up.Rule of mine bottom pressure variation in CBM mine closure was obtained on the basis of parameters of WL1 mine.Results showed that in double logarithmic curve of mine bottom pressure recovery,the gradients at gas-water two-phase flow phrase and water single-phase flow phrase were different,respectively were 0.3919 and 0.0682.Later curve was near to horizontal line,which was similar with double logarithmic curve of "two-open and two-close" pressure recovery.With bottom pressure recovery,permeability of reservoir and desorption radius gradually decreased.When bottom pressure recovered to 2.36MPa from 1.1MPa,desorption radius reduced to 4.46m from 11.97m,methane output reduced 444.25 m3/d from 3200m3/d.