三轴围压下煤岩吸附膨胀特性与渗透性动态变化.pdf

2012年9月,第18卷,第3期,539-543页
高校地质学报
September 2012, Vol 18, No3, p 539-543
Geological Journal of China Universities
三轴围压下煤岩吸附膨胀特性与渗逶性动态变化
张松航,唐书恒,万毅,舒广强
中国地质大学(北京)能源学院,北京100083
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ー应变效应,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岄显增大;媒样最大径向吸附应变与孔隙だ力的关系,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,说明两者对煤岩滲透性影响的实质相同,即煤岩孔除、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
客观地预冽煤岩渗透性动态变化规律。
关键词:煤层气;有效应力;吸附膨胀;渗透率;沁水盆地
中图分类号:P618.1
文献标识码:A
文章编号:1006-7493(2012)03-0539-05
Changes in Adsorption Swelling Properties and Dynamic Permeability of
Coals Under Triaxial Confining Pressure
ZHANG Songhang, TANG Shuheng, WAN Yi, SHU Guangqiang
School of Energy and Resources, China University of Geosciences, Beijing 100083, China
Abstract: Dynamic changes of the porosity and permeability of coal reservoirs during the coalbed methane(CBM)rainage is one
of the hot topics in the research of CM developmental geology. Stress and strain effects of an anthracite sample from the Jincheng
area was investigaled under triaxial stress conditions and the ynamic 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 e described by the form of the Langmuirs unction. 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 rauall reduee or close under the stress. In addition, the Klingberg s effert should be considered
under the condition of lower pore pressure. Upon examination, the ynamic coal permeability can be objectively predicted by the
Key words: coalbed methane; effective stress; adsorption swelling: permeability; Qinshui basin
FirstauthorZHANGSonghang,LecturerE-mail:zshangrlream@126.com
煤层气排采过程中,甲烷解吸造成煤基质收热点之一。对此问题,前人开展过大量研究(唐
缩和有效应力改变,导致煤储层孔隙度和渗透率巨鹏等、2006; Karacan,2007; Majewska an
产生动态变化,给煤层气井产能评价和开发方案/ ietek,2007; Pan and Conne!,2007;隆清明等,
制定带来困难,成为煤层气开发地质机理研究的2008; Bustin et al.,2008;彭守建等,2009;
收稿日期:2012-03-11;修回日期:2012-05-07
基金项目:国家科技重大专项(2011ZX0503403);国家重点基础研究发展计划(20)CB21964);国家角然科学项目(40972108)和中央高
校基木科研业务费专项资金联合资坳
作者简介:张松航,1982年生,讲师,煤层气地质与开发研究方向;E-mail:Zshanudreamn126.com