多煤层条件下现今地应力特征与煤层气开发  

Characteristics of present-day in-situ stress field under multi-seam condtions:Implications for coalbed mthane development

作　　者：鞠玮[1,2] 姜波[1,2] 秦勇[1,2] 吴财芳[1,2] 李明[1,2] 徐浩然[2] 王胜宇 JU Wei;JIANG Bo;QIN Yong;WU Caifang;LI Ming;XU Haoran;WANG Shengyu(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education,China University of Mining and Technology,Xuzhou 221008,China;School of Resources and Geosciences,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学煤层气资源与成藏过程教育部重点实验室,江苏徐州221008 [2]中国矿业大学资源与地球科学学院,江苏徐州221116

出　　处：《煤炭学报》2020年第10期3492-3500,共9页Journal of China Coal Society

基　　金：国家科技重大专项资助项目(2016ZX05044);江苏高校优势学科建设工程资助项目()。

摘　　要：我国煤层气资源较为丰富,滇东地区是我国长江以南著名的煤层气产区,其内雨旺区块二叠系煤层气资源丰富,具有可观的开发前景。现今地应力状态是影响煤层气勘探开发的重要地质因素,对有效开发煤层气资源具有实践指导意义。但目前对雨旺区块现今地应力的研究仅限于利用注入/压降测试数据开展的地应力大小统计学分析,没有揭示出多煤层发育区不同类型岩石内地应力分布的差异性。本次研究中,首先通过对成像测井资料的解译,揭示钻井诱导缝和钻孔崩落的发育特征,并基于其与地应力的关系确定雨旺区块现今地应力方向;然后再利用常规测井资料,在注入/压降实测地应力数据约束下,基于Anderson修正模型预测雨旺区块二叠系煤层现今地应力的大小及其分布规律。结果表明:滇东雨旺区块现今地应力方向整体呈现为近N—S的优势方位;煤层现今地应力大小随着埋藏深度的增加而增大,水平最大主应力(SHmax)、水平最小主应力(Shmin)和垂向主应力(Sv)大小总体上遵循SHmax≥Sv>Shmin的关系,水平应力起主导作用,表现为走滑型应力机制。在现今地应力场的控制下,雨旺区块内煤储层渗透性随有效地应力的增大而变差,煤层内走向为330°~150°的割理对煤层气开发贡献更大。走滑型应力机制会造成煤层压裂改造后形成的压裂缝沿垂向扩展。另外,雨旺区块煤层内水平应力差相对较小,一般在6 MPa左右,据此推测可在煤层内形成复杂压裂缝系统。本次研究量化分析了雨旺区块现今地应力状态,其结果可以为滇东雨旺区块煤层气勘探开发提供有益的现今地应力成果参考。China has abundant coalbed methane(CBM)resources.The eastern Yunnan region is a famous CBM production area in the south of Yangtze River,where the Yuwang Block has abundant CBM resources with some considerable development prospects.The present-day in-situ stress state is an important geological factor influencing the exploration and development of CBM resources,which indicates some practical implications for effective CBM development.However,the current study on the present-day in-situ stress state within the Yuwang Block is only the statistic analysis based on some injection/falloff well tests.The differential distribution of stresses within various types of rocks has not been revealed in the areas with multi-seam conditions.Hence,in this study,the interpretations of drilling-induced fractures(DIFs)and borehole breakouts(BOs)from imaging logs were first carried out.The present-day in-situ stress orientation was determined based on the relationship between stress orientation and DIFs/BOs.Stress magnitudes in the Permian coal seams were calculated using the revised Anderson model corrected with measured stress data from the injection/falloff well tests.The results show that a dominant in-situ stress orientation with N-S-trending appears in the Yuwang Block.Stress magnitudes in coal seams generally increase with burial depth,and the magnitudes of the horizontal maximum principal stress(SHmax),horizontal minimum principal stress(Shmin)and vertical stress(Sv)follow the relationship SHmax≥Sv>Shmin,indicating a strike-slip faulting stress regime.Under the present-day in-situ stress field,the permeability in coal seams will decrease along with the increase of effective in-situ stresses.Those cleats with the strike of about 330°-150°contribute more to the CBM development in the Yuwang Block.Hydraulic fractures may propagate vertically under the strike-slip faulting stress regime.In addition,the horizontal stress difference is relatively low(about 6 MPa),which tends to form a complex hydraulic fracture system.This stu

关 键 词：现今地应力 煤层气 多煤层条件 雨旺区块 滇东地区 二叠系煤层 

分 类 号：P618.11[天文地球—矿床学]