页岩储层水平最小主应力实测与分布规律  

Measurement and distribution of horizontal minimum principle stress of shale reservoir

作　　者：孙东生[1,2] 禚喜准 淡永[4] 李阿伟[1,2] 杨跃辉[1,2] 陈群策 SUN Dongsheng;ZHUO Xizhun;DAN Yong;LI Awei;YANG Yuehui;CHEN Qunce(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of In-situ Stress Measurement and Monitoring,China Geology Survey,Beijing 100081,China;Department of Geology,Liaoning Technical University,Fuxin 123000,China;Institute of Karst Geology,Chinese Academy of Geological Sciences,Guilin 541004,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国地质调查局地应力测量与监测重点实验室,北京100081 [3]辽宁工程技术大学地质系,辽宁阜新123000 [4]中国地质科学院岩溶地质研究所,广西桂林541004

出　　处：《中国石油大学学报（自然科学版）》2021年第5期80-87,共8页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金项目(42174122);中国地质调查局地质调查项目(DD20190085,DD20190722,DD20190723)。

摘　　要：水平最小主应力是非常规油气储层压裂设计、压裂缝高控制和压裂后效果评价的重要基础数据。利用自主研发的深孔水压致裂原位地应力测试系统,对黔东南地区寒武系牛蹄塘组泥页岩储层进行地应力实测,获取深度1179~1188 m泥质粉砂岩层段水平最小主应力为24.9~25.3 MPa,1207~1208 m灰岩层段的水平最小主应力为21.4 MPa。结合公开报道的泥页岩储层地应力测量结果,定量评价泥页岩储层内水平最小地应力分布规律。结果表明:泥页岩储层内地应力明显受岩石的矿物含量控制,随着黏土等塑性矿物含量的增加,水平最小主应力明显增大;在区域构造应力场作用下,泥页岩层的水平最小主应力比砂岩或灰岩等脆性夹层高4~15 MPa;对于深层页岩气,应选择脆性矿物含量高的水平最小主应力低值区作为水平井穿行层段,不仅有利于压裂缝的起裂和扩展,且裂缝的闭合压力低,可有效避免支撑剂的破碎和嵌入,保持压裂缝的导流能力。The horizontal minimum principal stress is a key parameter for hydraulic fracturing design of unconventional reservoirs.In this study,the horizontal minimum principal stress was obtained using an in situ stress measurement method while hydraulic fracturing in the Niutitang Formation of Cambrian at the southeast area of Guizhou province.The horizontal minimum principal stress is 24.9-25.3 MPa at the depth of 1179-1187 m with the interval of clayey siltstone,and it is 21.4 MPa at the depth of 1207-1208 m intercalated within limestone.Referring to the in situ stress measurement results of similar formations,the distribution of the in situ stress magnitude within the shale formation was evaluated.The results show that the magnitude of the horizontal minimum principal stress in shale reservoir is mainly controlled by the formation lithology which increases obviously with the increase of the content of plastic minerals such as clay.Under the action of regional tectonic stress field,the horizontal minimum principal stress of shale is 4-15 MPa higher than that of sandstone or limestone.The research results can be used for quantitative evaluation of the in situ stress difference between shale and brittle interbed formations.For deep shale gas reservoirs,layers with high brittle mineral content and low value of horizontal minimum principal stress are recommended for horizontal wells,which are conducive to the initiation and propagation of fractures,and have low closure pressure after fracturing operation.

关 键 词：水平最小主应力 水压致裂法 页岩储层 塑性矿物含量 深层页岩气 

分 类 号：TE122.14[石油与天然气工程—油气勘探]