沁水盆地南部地应力场特征及其研究意义  

Characteristics of in-situ stress field in Southern Qinshui Basin and its research significance

作　　者：孟召平[1,2] 田永东 李国富 

机构地区：[1]中国矿业大学(北京)地球科学与测绘工程学院,北京100083 [2]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002 [3]沁水蓝焰煤层气有限责任公司,山西晋城048204

出　　处：《煤炭学报》2010年第6期975-981,共7页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(40772100);国家重点基础研究发展计划(973)资助项目(2007CB209405);教育部留学回国人员科研启动基金资助项目

摘　　要：采用水压致裂测量地应力方法,测得了沁水盆地南部45口煤层气井主采煤层地应力分布,通过统计分析,建立了主采煤层地应力与煤层埋藏深度之间的相关关系和模型,分析了地应力在煤储层渗透性及压裂研究中的意义。研究结果表明:沁水盆地南部最大水平主应力为6.42～41.86MPa,平均为17.21MPa;最大水平主应力梯度为1.17～4.79MPa/100m,平均为2.64MPa/100m;最小水平主应力3.30～26.40MPa,平均为11.391MPa;最小水平主应力梯度为0.99～2.85MPa/100m,平均为1.77MPa/100m。主应力均随着煤层埋藏深度的增大而增高,呈线性关系。在650m以浅煤储层地应力状态主要表现为σv>σhmax>σhmin,最小水平主应力小于12MPa,现今地应力状态处于伸张带;在650～1000m煤储层地应力状态转化为σhmax≈σv≈σhmin,最小水平主应力为12～20MPa,现今地应力状态由伸张带转化为压缩带的过渡;在1000～1500m煤储层地应力状态为σhmax≈σv≈σhmin,最小水平主应力大于20MPa,现今地应力状态转化为压缩带。在地应力的作用下,裂缝逐渐趋于闭合,煤储层渗透率急剧下降。同时,地应力对煤储层水力压裂裂缝扩展产生重要影响,水力压裂裂缝均沿着最大主应力方向扩展。Adopted hydraulic fracturing method to measure in-situ stress,obtained in-situ stress distribution of main minable coal seams of 45 coalbed methane testing wells in Southern Qinshui Basin,through statistical analysis,the correlations and their models between in-situ stress in main minable coal seams and the burial depth of coal seam were established,the significance of in-situ stress in research of coal reservoir’s permeability and hydraulic fracturing was analysised.The result shows that the maximum horizontal principal stress in Southern Qinshui Basin is 6.42～41.86 MPa,the average is 17.21 MPa;the maximum horizontal principal stress grads is 1.17～4.79 MPa/100 m,the average is 2.64 MPa/100 m;the minimum horizontal principal stress is 3.30～26.40 MPa,the average is 11.391 MPa,the minimum horizontal principal stress grads is 0.99～2.85 MPa/100 m,the average is 1.77 MPa/100 m.It is also noticed that principal stresses all increase following a linear relationship as coal seam burial depth increase.The coal reservoirs with a burial depth shallower than 650 m,in-situ stress state principally shows σvσhmaxσhmin,the minimum horizontal principal stress is below 12 MPa,recent in-situ stress state is located tension zone;the in-situ stress state of coal reservoirs with 650～1 000 m in depth transforms into σhmax ≈σv≈σhmin,the minimum horizontal principal stress is 12～20 MPa,recent in-situ stress state is situated transition zone which transforms from tension zone into compression zone;the coal reservoirs with 1 000～1 500 m in depth,in-situ stress state is σhmax ≈σv≈σhmin,the minimum horizontal principal stress is over 20 MPa,recent in-situ stress state becomes compression zone.Under the effect of in-situ stress,fissures are tend to closed gradually,and the coal reservoir’s permeability drops rapidly.Simultaneity,in-situ stress produces an important influence on crack propagation of coal reservoir’s hydraulic fracturing,direction of crack propagation is all along the maximum horizontal prin

关 键 词：沁水盆地南部 地应力 渗透性 水力压裂 

分 类 号：TD311[矿业工程—矿井建设]