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。
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 desorhed 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 coal seam were interconnected by fracturing fissures. The conical depression of confined water head from draining is called as coal reservoir pressure funnel. The CBM in the range of the funnel will be desorbed and released in different degrees, which is the dynamics mechanism of CBM drainage.
出处
《高校地质学报》
CAS
CSCD
北大核心
2012年第3期583-588,共6页
Geological Journal of China Universities
基金
国家重点基础研究发展计划(2009CB219605)
国家科技重大专项(2011ZX05034-01)
中国博士后科学基金 (20110491473)
中央高校基本科研业务费(2010LKDZ07
关键词
煤层气排采
动态变化
储层压降
水头
coalbed methane drainage
dynamic variation
coal reservoir pressure drop
water head
