沁水盆地压裂裂缝展布及对煤系“三气”共采的指示意义  

Fractures distribution of Qinshui basin and its indicative significance to unconventional gas co-exploration in coal measures

作　　者：侯晓伟[1,2] 朱炎铭[1,2] 付常青[1,2] 刘娇男[1,2] 

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：《中国矿业大学学报》2016年第4期729-738,共10页Journal of China University of Mining & Technology

基　　金：山西省煤基重点科技攻关项目(MQ2014-02);国家自然科学基金项目(41472135);江苏省研究生创新工程研究生科研创新计划项目(KYLX15_1397)

摘　　要：为提高煤系"三气"共采压裂效果,对沁水盆地煤系"三气"共采进行了压裂配套设计.以煤系"三气"共生成藏为共采前提,基于水力压裂、岩石力学等测试手段研究区域应力特征,依据最大周向应力和二维线弹性断裂理论探讨应力作用下压裂裂缝展布规律,认为沁水盆地煤系储层具有充足的气源供给和合适的空间叠置关系,具有很好的煤系"三气"共采前景.研究结果表明:应力控制下各类储层起裂压力大小为:煤<砂岩<泥页岩,煤起裂压力转换深度最大;天然裂隙起裂程度大小为:泥页岩>砂岩>煤;压裂新起裂角展布趋势相似.压裂效果综合指数砂岩(0.041)>煤岩(0.036)>泥页岩(0.025).示范井揭示煤系"三气"可分为3类次级气藏,5种气藏组合.基于递进排采理论对各类气藏组合进行压裂配套设计,极大程度避免对临近气藏的压裂干扰.To improve the fracturing effect of unconventional gas co-exploration, hydraulic fracturing matching scheme was applied in the exploration process of coal measures in Qinshui basin. Taking the coexistence accumulation of unconventional gas in coal measures as a prerequisite, the regional crustal stress characteristics were analyzed based on testing approaches such as hydraulic fracturing and rock mechanics etc. According to the maximum hoop stress and two-dimensional elastic fracture theories, the fracturing fractures distribution trends under crustal stress were also studied. With an adequate gas source and a suitable spatial superimposed relationship, coal measures in Qinshui basin are considered as reservoirs with great coexploration prospect. The results show that under the crustal stress controlling effect, the initial fracture pressure of mud shale, sandstone and coal presents smaller and smaller, but the pressure conversion depth of coal is the highest. In terms of natural fractures initiation, the order from large to small is mud shale, sandstone, coal; however, the new initiation angle of different reservoirs shows the same distribution trends. Indicating a declining trend, the fracturing composite index of sandstone, coal and mud shale are 0. 041, 0. 036 and 0. 025 respectively. The typical well demonstrates that the unconventional gas reservoirs can be divided into three types of secondary reservoirs and five types of reservoirs combinations. Based on progressive discharge and mining theory, each type of reservoirs combination is guided by hydraulic fracturing matching scheme to avoid any fracturing interference to adjacent reservoirs.

关 键 词：煤系“三气”共采 二次生烃 起裂压力 天然裂缝起裂 裂缝展布 压裂配套 

分 类 号：P624[天文地球—地质矿产勘探]