非低阶煤煤层气解吸关系研究

Experimental Study of Coalbed Methane Desorption Formula of Non-Low Rank Coal

煤层气解吸作用的研究可较好地预测产气量和气量持续周期。对当前数个煤层气勘探开发较为活跃地区的煤进行了吸附解吸实验,通过对实验数据拟合分析,得到煤层气降压解吸服从数学模型Vd=adbdp/1+bdp+c。在煤层气井排水降压产气过程中,采用此模型对煤层气的解吸量进行计算,揭示了降压解吸滞后是由于剩余含气量c的存在,解吸量ad与最大含气量amax线性相关,最大解吸率为c/amax,生产上要提高解吸量只能通过改变吸附系统吸附热与解吸速率。通过2口直井与2口水平井的排采实践对本文研究结论进行了验证。

Research of the coalbed methane （CBM） desorption can be used to predict gas production and gas continued period. The adsorption and desorption experiments for the coals are made in some active CBM exploration and development regions. Through the analysis of experimental data, the pressure-reduced desorption formula for the CBM follows Vd=adbdp/1＋bdp＋c.Calculates the CBM desorption quantity with the formula during the well drainage process. It reveals that the lag of pressure reducing desorption is due to the presence of residual gas content c, the desorption quantity ad maximum gas content amax show a linear correlation, the maximum desorption rate is c/amax, and improves the desorption in the production only by changing the heat of adsorption and the desorption rate. It is verified through the drainage practice of two vertical wells and two horizontal wells.