沁南煤层气井产能影响因素分析及开发建议

Analysis on influence factors of coalbed methane wells productivity and development proposals in southern Qinshui Basin

通过比较山西沁水盆地南部57口煤层气井在1.5 a时间内的产气产水特征,分析了影响该区煤层气井产能变化的地质及工程特征因素,并提出相应的开发建议。结果显示:煤层埋深及地下水动力条件、含气量以及气井所处的构造部位是影响沁南煤层气井产能的主控地质因素;开发前的煤储层压裂改造规模、井底流压下降速度以及排采速度是重要工程因素。同时,提出了相应的参数指标:500～700 m的埋深,大于15 m3/t的含气量;早期排水期,采取比较大的降压幅度和比较大的排采冲次,分别为0.022 MPa/d和3.0次/min;出现产气高峰后,开始缓慢降压和降低冲次,分别为0.002 MPa/d和0.4次/min。

By comparing the gas and water production characteristics of 57 coalbed methane（CBM） wells in southern Qinshui Basin in 1.5 years,the geological factors and engineering factors which affecting the productivity change of CBM wells in this area were analyzed,and the corresponding development proposals were proposed.The results show that coal seam buried depth and hydrodynamic conditions,gas content and tectonic position of CBM wells are the main geological controlling factors that affecting the productivity of CBM wells in southern Qinshui Basin,and fracturing treatment scale of coal reservoir before development,descending speed of the bottom hole flowing pressure and exploitation rate are the important engineering factors.Meanwhile,put forward the corresponding parameter indexes,that is buried depth at 500～700 m,gas content should greater than 15 m3/t,and larger pressure drop（about 0.022 MPa/d） and stroke（3.0 /min） are favorable in the early drainage period,and smaller pressure drop（0.002 MPa/d） and stroke（0.4 /min） should be applied when the gas peak appears.