三轴围压下煤岩吸附膨胀特性与渗透性动态变化  

Changes in Adsorption Swelling Properties and Dynamic Permeability of Coals Under Triaxial Confining Pressure

作　　者：张松航[1] 唐书恒[1] 万毅[1] 舒广强[1] 

机构地区：[1]中国地质大学(北京)能源学院,北京100083

出　　处：《高校地质学报》2012年第3期539-543,共5页Geological Journal of China Universities

基　　金：国家科技重大专项(2011ZX05034-03);国家重点基础研究发展计划(2009CB219604);国家自然科学项目(40972108);中央高校基本科研业务费专项资金联合资助

摘　　要：煤层气排采过程中煤储层孔隙度和渗透率的动态变化,是煤层气开发地质研究的热点之一。本文利用晋城无烟煤样,分析了三轴应力条件下煤岩的应力-应变效应,讨论了煤样渗透率的动态变化规律。结果表明,围限压力条件下,煤岩吸附甲烷后其抗压强度明显增大;煤样最大径向吸附应变与孔隙压力的关系,可用朗格缪尔方程形式予以描述;煤岩渗透性与有效应力、煤岩吸附膨胀量均呈负指数关系,说明两者对煤岩渗透性影响的实质相同,即煤岩孔隙、裂隙受到应力作用逐渐减小或闭合。同时,在较低孔隙压力条件下,需考虑克林伯格效应对煤层渗透性的影响。经检验,S-D模型能够较为客观地预测煤岩渗透性动态变化规律。Dynamic changes of the porosity and permeability of coal reservoirs during the coalbed methane （CBM） drainage is one of the hot topics in the research of CBM developmental geology. Stress and strain effects of an anthracite sample from the Jincheng area was investigated under triaxial stress conditions and the dynamic permeability of the sample was discussed. Results showed that the compressive strength of the sample increased significantly after methane adsorption under confining pressure. Correlation of the maximum radial strain to pore pressure of the sample can be described by the form of the Langmuir＇ s function. Permeability of the sample has a negative exponential relationship with both the effective stress and adsorption-induced swelling, indicating that the impact of both adsorption-induced swelling and effective stress on the permeability is substantially the same. In other words, the pore and fracture gradually reduce or close under the stress. In addition, the Klingberg＇ s effect should be considered under the condition of lower pore pressure. Upon examination, the dynamic coal permeability can be objectively predicted by the S-D model.

关 键 词：煤层气 有效应力 吸附膨胀 渗透率 沁水盆地 

分 类 号：P618.11[天文地球—矿床学]