1. College of Mining Engineering,Liaoning Technical University,Fuxin　 123000,China;2. State Key Laboratory for GeoMechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou　 221116,China;3. State and Local Joint Engineering Laboratory for Gas Drainage and Ground Control of Deep Mines,Henan Polytechnic University,Jiaozuo　 454003,China

为了提高深部煤储层产气规律预测准确性、减小气井设计误差,分析了深部煤储层特征参数随埋深的变化规律,针对目前煤层气研究忽略了温度、地下水等因素问题,基于已建立的深部煤层气抽采流-固-热耦合模型,进行深部煤层气抽采数值模拟,分析不同地应力、初始渗透率、储层压力和温度等深部特征参数以及不同埋深条件下煤层气抽采的储层参数和产气演化规律。结果表明:渗透率变化为地应力增加、温度降低和煤层气解吸引起的煤基质收缩效应与储层压力降低引起的煤基质膨胀效应的综合竞争结果;随着煤层气和水被采出,储层温度降低和煤层气解吸占主导,储层渗透率升高;地应力对深部储层渗透率比例的变化起着主要作用,初始渗透率对产气速率起着控制作用;当煤层埋深小于临界埋深时,产气量随埋深逐渐增加,达到临界埋深后,产气量随埋深逐渐降低;低渗透率是制约埋深超千米的气井高产的关键。

In order to improve the accuracy of productivity prediction in deep reservoir and reduce the design error of CBM well,the authors analyzed the relationship between the characteristic parameters of coal reservoir and its seam depth. A series of numerical simulation were carried out based on an established hydraulic-mechanical-thermal coupled model (HMT) for deep CBM extraction. The law of deep extraction with different characteristic parameters and the in- fluence of seam depth on gas production were analyzed. Results show that the evolution of permeability ratio is the competitive result of the matrix shrinkage effect caused by geostress increase,temperature reduction and methane de- sorption,and the matrix swelling effect caused by reservoir pressure decrease. The reservoir temperature reduction and pressure decrease during CBM extraction will lead to an increase of permeability. The geostress plays a leading role in the variation of permeability ratio in deep coal reservoir,and the initial permeability of coal reservoir in stress-free state plays a controlling role in gas production. When seam depth is less than a critical depth,gas production will increase with seam depth. While exceeding the critical depth,gas production will decrease with seam depth. Hence,the effective measures for creating permeability is the key to achieve high yield for CBM extraction in the coal reservoirs buried deeper than 1 000 m.

国家重点研发计划资助项目(2016YFC0801407-2)；国家自然科学基金资助项目(51674132)；深部岩土力学与地下工程国家重点实验室开放基金资助项目(SKLGDUEK1510)；

Fan Chaojun,Li Sheng,Luo Mingkun,et al. Deep CBM extraction numerical simulation based on hydraulic-mechanical-thermal coupled model[J]. Journal of China Coal Society,2016,41(12):3076-3085.