不同脆性致密砂岩裂缝扩展规律实验  

Experiments on Hydraulic Fracture Propagation in Tight Sandstones with Different Brittleness

作　　者：叶亮[1,2] 李宪文 马新星[1,2] 李四海 赵倩云[1,2] 葛强 YE Liang;LI Xianwen;MA Xinxing;LI Sihai;ZHAO Qianyun;GE Qiang(PetroChina Changqing Oilfield Company,a.Oil and Gas Technology Research Institute,Xi’an 710018,China;National Engineering Laboratory for Explora-tion and Development of Low-Permeability Oil and Gas Fields,Xi’an 710018,China;College of Petroleum Engineering,China University of Petroleum,Beijing 102249,China)

机构地区：[1]中国石油长庆油田分公司油气工艺研究院,西安710018 [2]中国石油长庆油田分公司低渗透油气田勘探开发国家工程实验室,西安710018 [3]中国石油大学(北京)石油工程学院,北京102249

出　　处：《新疆石油地质》2020年第5期575-581,共7页Xinjiang Petroleum Geology

摘　　要：岩石的脆性与致密油气储集层压裂改造效果密切相关,但致密岩石的脆性对裂缝扩展规律的影响仍不明确。基于真三轴压裂模拟实验系统,对鄂尔多斯盆地东部3种不同脆性致密砂岩开展了压裂模拟实验,分析了脆性、压裂液类型和层理对裂缝扩展规律的影响。研究表明,山1段致密砂岩脆性最强,长7段致密砂岩次之,盒8段致密砂岩脆性最弱;在层理不发育的条件下,相比于中等脆性的盒8段致密砂岩,强脆性的山1段致密砂岩采用滑溜水压裂形成的单条裂缝扩展更充分,液态CO2压裂形成的分支裂缝数量更多;在层理发育的条件下,长7段致密砂岩采用滑溜水压裂和液态CO2压裂形成的裂缝的形态均较复杂;相比于滑溜水压裂,液态CO2压裂形成的裂缝宽度更小;液态CO2压裂更适用于脆性较强、层理发育的长7段致密砂岩储集层压裂改造。Rock brittleness is closely related to the effectiveness of fracturing treatment in tight reservoirs,but the influence of the brittle⁃ness of tight rock on fracture propagation is still unclear.In order to study how hydraulic fractures propagate in tight sandstones with differ⁃ent brittleness,fracturing experiments were conducted on three types of tight sandstone using a true tri⁃axial fracturing simulation system.The influences of rock brittleness,fracturing fluid and bedding on fracture propagation were analyzed.Experimental results show that Shan⁃1 tight sandstone has the strongest brittleness,followed by Chang⁃7 tight sandstone,and He⁃8 tight sandstone has the weakest brittleness.In the case with less beddings,the fracture induced by slick water extends more completely,and more fracture branches are created by liq⁃uid CO2 in the most brittle Shan⁃1 tight sandstone than the He⁃8 tight sandstone.In the case with more beddings,the fracture shapes in⁃duced by liquid CO2 in Chang⁃7 tight sandstone are more complex than those in the relatively homogeneous Shan⁃1 and He⁃8 tight sand⁃stones.Compared with slickwater,the fractures induced by liquid CO2 is narrower.Liquid CO2 fracturing is more suitable for the most brit⁃tle Chang⁃7 tight sandstone reservoir with many beddings.

关 键 词：鄂尔多斯盆地 脆性 致密砂岩 滑溜水压裂 液态CO2压裂 裂缝扩展 裂缝形态 

分 类 号：TE357[石油与天然气工程—油气田开发工程]