沁水盆地赵庄矿3号煤层地面煤层气抽采低产原因分析

Analysis on causes of low production of surface CBM extraction from No.3 coal seam in Zhaozhuang Mine,Qinshui Basin

在对沁水盆地赵庄矿煤层气开发地质、煤层气生产井资料深入研究的基础上,分析、总结了区内煤层气直井低产原因,并据此提出了区内地面抽采后续开发方向。研究认为:3号煤层气含量偏低、含气饱和度低、临储比低,致使排采阶段气含量可降幅度低,是其低产的宏观表征;3号煤储层不匹配孔级,较差连通性,即微、小孔为主,中孔次之,大孔不发育,微裂隙连通性差,致使扩散缓慢、影响储层改造和抽采效果,是其低产的微观表征;3号煤层远高于顶底板塑性及相近的水平应力,进一步造成改造缝长受限,泄流面积不足。因此,建议区内后续地面抽采方式应以增大泄流面积开发方式为主。

This paper was based on the in-depth study of coalbed methane development geology and CBM production well data in Zhaozhuang Mine,Qinshui Basin,which analyzed and summarized the reasons for the low production of CBM vertical wells in the area,and proposed the subsequent development direction of surface drainage in the area.The study believed that the low content of coalbed methane,low gas saturation,and low temporary reserve ratio result in a low reduction in gas content during the drainage stage,which was a macroscopic characterization of its low production;the No.3 coal reservoir did not match the pore level.Poor connectivity,that is,micro-pores and small pores were the main ones,followed by meso-pores,large pores were not developed,and micro-fractures were poorly connected,resulting in slow diffusion,affecting reservoir reconstruction and drainage effects,which were microscopic signs of low yield;No.3 coal seam was much higher than the roof and floor plasticity and similar horizontal stress,which further caused the length of the reformed joint to be limited and the drainage area was insufficient.Therefore,it was suggested that the follow-up surface extraction method in the area should be the development method of increasing the discharge area.