摘要
煤层气开发过程中煤岩应力敏感性对渗透率产生影响,而渗透率的变化直接决定着煤层气资源商业开采的成败。试验测定了鄂尔多斯盆地老坑口矿井煤岩在平行面割理、垂直面割理及垂直层理面3个不同方向的渗透率随有效应力变化情况,对比分析了增压过程和降压过程中不同割理方向煤岩应力敏感性差异。结果表明:不同割理方向煤岩应力敏感强烈阶段有所不同,平行面割理方向应力敏感强烈阶段集中在有效应力小于8 MPa,垂直面割理及垂直层理面则分别在6和4 MPa附近;鉴于煤层气井排采中储层应力敏感效应的影响,提出动液面在接近煤层中深200 m后,谨慎降液排采,同时建议实施减小渗透率降低幅度和时间的排采;基于平行面割理方向煤岩渗透率更有优势,因此,井网长轴平行面割理方向是井网部署合理方向。
Coal stress-sensitivity has serious impacts on the value of permeability during coalbed methane development, meanwhile, the permeability change would directly determine the success or failure of commercial exploitation of coalbed methane resources. The experi-mental studies have done for permeability change with different effective stress in different directions of coal in the Laokengkou mine of southeastern margin of Ordos Basin,such as parallel face cleats,vertical face cleats and vertical bedding.The comparative analysis of coal permeability loss value accompanying direction changes during the pressurization and step-down process was done.The results showed that the phases of stress sensitivity were varied in different coal cleat orientation,where the strong stress sensitivity phase for parallel to the face cleats focuses on the effective stress was less than 8 MPa range,vertical cleats and vertical bedding planes concentrated in less than 6 MPa,4 MPa respectively.Considering the impacts of stress sensitivity during drainage for coalbed methane wells in nearly 200 m deep coal seam should carefully extraction,reducing amplitude of permeability reduction and time schedule,were proposed.Based on the permeability advantage of face cleats,the well network layout is the long axis of well network paralleling to the face cleats.
出处
《煤炭科学技术》
CAS
北大核心
2014年第11期21-25,共5页
Coal Science and Technology
基金
中国石油化工集团科研资助项目(G5800-11-ZS-YTB46)
关键词
煤岩体
应力敏感
割理方向
渗透率损失
煤层气井排采
井网优化
coal rock body
stress sensitivity
cleat direction
permeability loss
coalbed methane well drainage
well pattern optimization
