第39参第2期 2017年3月
石油钻采工艺
OIL DRILLING & PRODUCTION TECHNOLOGY
文章编号：10007393(2017）02015805
DOI:10.13639/j.odpt.2017.02.006
甲烷气渗流作用对煤岩强度白
的影响
王力
中联煤层气有限责任公司
引用格式：王力.甲烷气渗流作用对煤岩强度的影响[J］.石油钻采工艺，2017,39(2)：158-162.
Vol. 39 No. 2 Mar.2017
摘要：煤层气井在排采生产阶段，由于甲烷的不断脱附、渗流，煤层孔隙压力和有效应力逐渐发生变化，煤岩力学强度减弱，进而对储层孔陈度、渗逹率，甚至井壁稳定性均有一定影响。对煤层气在煤层间的渗流过程与煤岩的力学性质间的耦合关系遗行了室内实验，为煤层气井完并、开发等方案制定提供了理论支持。声波发射实验和单轴/三轴抗压实验结果表明，随着 CH4流经煤岩卷心时间的延长，煤岩弹性模量透渐降低，表明煤岩力学强度下降。单轴/三轴抗压实验表明，煤岩的弹性模量和最大抗压强度随图压的下降而减小，且在高图压条件下下降较慢，低压条件下下降较快。该结果表明，在煤层气生产一定时间后，井下煤层可能产生损、摔块而影响生产作业。
关键词：煤层气；渗流；煤岩；力学性质
中图分类号：TE34
文献标识码：A
Effect of methane gas seepage on coal rock strength
WANG Li
China United Coarlbed Methane Company, CNOOC, Beijing 100013, China
esse 39(2): 158-162.
Abstract: In the production stage of coalbed methane (CBM) wells, the pore pressure and effective stress of coal seams change gradually with the continuous methane desorption and seepage, and correspondingly the mechanical strength of coal rock decreases Consequently, the porosity and permeability of reservoirs and even the wellbore stability are, in a way impacted. In this paper, the coupling relationship between the seepage process of coalbed methane in coal seam and the mechanical property of coal rock was tested indoors. And it provides the theoretical basis for formulating CBM well completion and development schemes. Then, acoustic e d s e s s ae aaa osso een e saoss cores extends and the elastic modulus of coal rocks decreases gradually, indicating the decrease of its mechanical strength. The uniaxial/ triaxial compression test reveals that the elastic modulus and maximum compression strength of coal rocks decrease with the decreasing of confining pressure. And they decrease slowly (fast) when the confining pressure is high (low). It is demonstrated that downhole coal seams may collapse and drop after coalbed methane is produced for a while, and consequently the production and operation is impacted adversely
Key words: coalbed methane; seepage; coal rock; mechanical property
煤岩具有双重裂隙系统：裂缝体系和孔隙体系，前者是煤层气重要的渗透流通通道，后者是煤层
气主要的储集场所。煤岩的裂缝体系可分为割理与节理。节理将割理系统联系起来，使得煤岩的裂
基金项目：国家“十三五"油气重大专项（2016ZX05044003）“易漏易辑地层钻完井及储层保护技术研究"强题
第一作者：王力（1969-),2006年毕业于中国石油大学（华东）石油天然气工程专业，茂项士学位。2016年毕业于东北石油大学石沟与天
然气工程专业，获博士季位。主要从事钻并技术研究及一线生产管理工作，高城工程师。通试地址：北求市朝阳区酒仙梯路乙21号国实大厦。电话；010-84528505。E-mail：wangli72@cnooc.com.cn
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