关于煤层气排采动态变化机制的新认识-高校地质学报.PDF

2012 年 9 月，第 18 卷，第 3 期，583-588页 高 　校　地　质　学　报 September 2012，Vol. 18， No.3， p. 583-588 Geological Journal of China Universities 关于煤层气排采动态变化机制的新认识 汪吉林，秦 勇，傅雪海 中国矿业大学 资源与地球科学学院/煤层气资源与成藏过程教育部重点实验室，徐州 221116 摘要：对于影响煤层气排采动态的几个基本地质问题，从新的视角进行了分析。在此基础上，基于沁水盆地南缘寺河区块 3 号煤层上覆含水层的水文地质条件和岩石物理性质，模拟了煤层气井排采过程中储层压力降漏斗的大小，求出了储层压 力降漏斗影响下煤层气解吸、产出的量值，得到的模拟排采曲线与实际排采曲线变化趋势吻合较好。本文认为，煤层中只 有少量束缚水和一些重力水；煤层气井压裂增产形成的压裂缝使得煤层与顶板以上的含水层相互贯通，煤层气排采时抽排 的地下水实际上应是煤层顶板上方含水层的承压水；抽水形成承压水头降落漏斗（即储层压力降漏斗），其影响范围内的煤 层气得到不同程度的解吸和释放，这就是煤层气排采的动力学机制。 关键词 ：煤层气排采；动态变化；储层压降；水头 中图分类号：P618.11　　　　　　　　文献标识码：A　　　　　　　　文章编号： 1006-7493（2012）03-0583-06 New Insight Into the Methanism for Dynamic Coalbed Methane Drainage WANG Jilin, QIN Yong, FU Xuehai School of Resources and Earth Science, and Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process (CUMT), Ministry of Education, China University of Mining and Technology, Xuzhou 221116, China Abstract: Several basic geologic problems affecting the dynamic variation of coalbed methane (CBM) drainage was discussed from a new perspective. The size of the pressure drop funnel in coal reservoir during the CBM drainage was simulated according to the hydrogeological and petrophysical conditions of the aquifer above the No. 3 coal seam in the Sihe block, southern margin of the Qinshui basin. CBM desorbed and outputted amounts under the influence of the pressure drop funnel were computed, from which the simulated CBM production curve is consistent with the actual production curve very well. It is considered that there are no much of gravitational water contained in coal seam but a little bound water. It was confirmed that the water drained from a CBM well should come from the confined water in the aquifer above coal seam because the aquifer and