四川页岩压裂裂缝扩展实验及力学特性研究  

Experimental study and mechanical properties analysis of fracture propagation in shale formation, Sichuan Basin

作　　者：周健[1,2] 蒋廷学 ZHOU Jian JIANG TingXue(Sinopec Research Institute of Petroleum Engineering, Beijing 100101, China State key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100101, China)

机构地区：[1]中国石化石油工程技术研究院,北京100101 [2]页岩油气富集机理与有效开发国家重点实验室,北京100101

出　　处：《中国科学：物理学、力学、天文学》2017年第11期149-156,共8页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(编号:51490653);中国石化科技部课题(编号:P15173)资助项目

摘　　要：采用真三轴压裂物理模拟的方法,研究了四川页岩储层压裂过程中的水力裂缝扩展行为和裂缝形态.实验结果表明,四川页岩压裂裂缝扩展模式分为主裂缝多分支裂缝和网状复杂裂缝.在水平主应力差较高的实验条件下,压力曲线波动频率高且趋势平稳,实时声发射监测结果表明,在实验的前期压裂裂缝易穿过天然节理,并形成单一主裂缝,而在实验的后期易形成多分支裂缝;在水平应力差较低条件下,压力曲线波动频率高但是不时伴有压力陡降,声发射监测结果表明,水力裂缝扩展易沿着页岩天然裂缝系统扩展,并形成复杂裂缝形态.定义了水力裂缝垂直穿过页岩层理面时的临界摩擦系数,采用实验参数和结果,揭示了在上述条件下,水平地应力差异系数和临界摩擦系数之间的相互关系,随着水平地应力差异系数的增加,临界摩擦系数显著降低.上述研究对中国的深层页岩气开发具有一定的指导意义.Hydraulic fracturing single fracture propagation behavior kinds and fracture geometry in Chinese shale are studied through a series of tri-axial which experiments.Two of fracture geometry complex were found in Sichuan shale during fracturing differential tests,are main fracture with multiple frequency branches of and network high fractures.When is horizontal stresses data contrast real is high,the fluctuation fracturing hydraulic curve fracture fracture is and its trend stable.Meanwhile,and the of time acoustic during monitoring indicated that,tests,tends to cross natural formed interface during form stage a single main fracture the initial stages of the and small branches are the later of in the the tests.However,hydraulic horizontal abruptly fracture tends to propagate along natural fracture system and form complex fractures condition high,of there low differential declines stresses pressure contrast.in Beside,The although fluctuation coefficient frequency friction of fracturing hydraulic curve fracture is but are of the test.threshold of for crossing a frictional interface is defined,is revealed then based the relationship experimental friction between coefficient of horizontal stress difference and the of threshold relative coefficient of friction the on data.It is found fracture that,in this case,with an increasing stress difference,threshold results coefficient our of The for hydraulic crossing a frictional interface deep decreased significantly based on the of tests.above research has certain guiding significance for shale development in China.

关 键 词：页岩 裂缝扩展 裂缝形态 地应力 临界摩擦系数 声发射监测 

分 类 号：TE377[石油与天然气工程—油气田开发工程]