摘要
页岩压裂改造过程中渗透率变化和压裂缝扩展的机理对页岩气开发压裂工程设计具有重要意义,通过页岩岩心首次加载-卸载-二次加载流-固耦合物理模拟实验和二次加载实验后岩心微米CT成像分析,揭示出两个重要现象:(1)首次加载-卸载-二次加载过程,有助于提高岩心的渗透率;(2)在二次加载过程中,岩心渗透率随轴压增加出现增加或降低不同的现象,分别对应压裂缝的有序化和方向性扩展或无序化和局部糜棱化扩展.实验获得的认识对页岩储层压裂改造有两条启示:(1)泵入-停泵-再泵入循环压裂有助于改善页岩气储层的渗透率;(2)对天然裂缝发育的页岩储层,压裂规模的针对性设计十分关键.
The mechanisms of permeability variations and fracture extension are essential for hydraulic fracturing design in shale gas exploitation.Based on fluid-solid coupling physical experiments and Micro-CT imaging analysis,this study reveals two important phenomena：（1）loading-unloading-reloading cycle has an effect on increasing the permeability of shale samples,（2）during the reloading process,the permeability of shale samples show different trends with increasing axial pressure.In the permeability increasing case with increasing axial pressure,the fractures are produced directionally and orderly.In another case,the fractures are produced disorderly and locally mylonitic.The results show that（1）pumping-intermission-repumping multicycles could help modify the stimulation effect of in-site fracturing operations,and（2）hydraulic fracturing volume should be appropriately controlled for naturally fractured shale gas reservoirs.
出处
《地球科学（中国地质大学学报）》
EI
CSCD
北大核心
2016年第8期1376-1383,共8页
Earth Science-Journal of China University of Geosciences
基金
国家重点基础研究发展计划(973计划)(No.2013CB228002)
关键词
页岩气
流-固耦合
物理模拟实验
渗透率
CT成像
压裂改造
石油地质
shale gas
fluid-solid coupling effect
physical experiment
permeability
CT imaging
fracturing stimulation
petroleum geology
