考虑启动压力的煤层气直井采收率预测模型

Prediction model of recovery ratio about CBM vertical wells considering on starting pressure

为查明煤层气井组排采时各井产气量差异的主要原因,采用实验室启动压力梯度和渗透率关系测试实验与渗流理论方法,构建了考虑启动压力的煤层气垂直井采收率预测模型.晋城矿区潘庄区块煤层气井的采收率计算结果表明:临界解吸压力、煤储层的导流能力的大小对煤层气井采收率的影响较大.改善煤储层的导流能力是提高采收率的重要途径.煤储层临界解吸压力、产气半径的差异性导致人为划定的单井控制面积计算采收率的局限性.

In order to find out the gas production differences among wells during the drainage in the CBM wells group, this paper established the prediction model of recovery ratio about CBM vertical wells considering on starting pressure, which utilized the experimental test about the relationship between starting pressure gradient and permeability, combined with seepage theory, and considered the relationship between the coal reservoir permeability and starting pressure gradient, The results on Panzhuang block in Jincheng mining show that the sizes of critical desorption pressures and coal reservoir flow capacity are of important influencing factors to recovery rate of CBM wells, and improving the flow conductivity of coal reservoir is an important approach to improve recovery ratio. The differences in the critical desorption pressures and gas production radius lead to the limitations of calculated recovery ratio in artificially created single well control area.