School of Resources and Geosciences, China University of Mining and Technology, Xuzhou , China

为了查明煤层气开发中有效应力变化对含水中阶煤储层渗透性的影响,对黔西松河区块1+3号煤层的同一煤柱重复开展了应力敏感性试验,分析了重复荷载作用与饱水压力对煤储层渗透率及应力敏感性的影响机理,并探讨了煤层气井储层改造与排采优化措施。研究表明:重复荷载作用与煤样饱水压力共同影响着中阶煤储层气测渗透率及应力敏感性。随着重复荷载次数增加,煤体发生塑性-弹性变形演化,应力敏感性逐渐减弱,渗透率不可逆损害率降低。与10 MPa饱水压力相比,20MPa饱水煤样初始气测渗透率显著降低,应力敏感性减弱并逐渐趋于稳定。中阶煤储层微观孔裂隙发育,渗透率应力敏感性强,煤层气开发工程中应重视煤储层保护。

In order to ascertain an effective stress variation affected to the permeability of the water bearing and medium rank coal reservoir in the development of the coalbed methane, a stress sensitivity experiment was repeatedly conducted on a same coal pillar in No.1+3 seam of Songhe Block in West Guizhou. The paper had an analysis on the repeated load and saturated water pressure affected to the mechanism of the coal reservoir permeability and stress sensitivity and had a discussion on the reconstruction of coalbed methane well reservoir and the gas drainage optimized measures. The study results showed that the repeated load and the saturated water pressure of the coal sample would jointly influence permeability and stress sensitivity of the medium rank coal reservoir gas. With the number of the repeated loading increased, the coal mass would have a plastic-elastic deformation evolution, the stress sensitivity would steadily reduced and the failure rate of the permeability would irreversibly be reduced. In comparison with 10 MPa saturated water pressure, the initial gas permeability of 20 MPa saturated water coal sample would be obviously reduced and the stress sensitivity would be weakened and would be steadily stabilized. The micropore crack development of the medium rank coal reservoir was well and the stress sensitivity of the permeability was high. In the development engineering of the coalbed methane, more attention should be paid to the protection of the coal reservoir.

中国地质调查局“黔西川南及东北三江地区煤层气基础地质调查”资助项目(DD20160186)；