摘要
为了分析评估煤层气井压裂增产后的生产效果,以沁水盆地煤层气井为实例,通过G函数曲线、时间平方根曲线和双对数函数曲线预测煤层压裂裂缝闭合压力,并建立了煤层气井的地应力模型。基于该地应力模型的结果,将注入摩阻及停泵裂缝净压力2项指标与煤层气井压裂前后产能进行对比,并拟合了煤层气井平均日产气量与该2项指标之间的关系模型。结果表明:预测的煤层地应力与测试结果的误差仅为0.75 MPa;注入摩阻及停泵裂缝净压力与煤层气产能存在较好的相关性,压裂注入摩阻和停泵裂缝净压力越高,裂缝的复杂程度越高且延伸越困难,导致煤层气井产能越低。该理论方法可为煤层气井的地应力模型和压裂后产能效果预测提供参考。
In order to evaluate productivity after fracturing of coal-bed methane wells,closure stress of coalbed fracture was predicted with Function Curve G,square root of time curve,double logarithmic function curve and in-situ stress model of coal was established based on the coalbed methane wells of Qinshui Basin. According to in-situ stress model,net pressure,fracture friction and production were contrasted. Then a model to evaluate the productivity after fracturing was established with fitting the correlations between net pressure,fracture friction with productivity. The results showed that the error of the predicted stress and well testing result was 0.75 MPa. There were good relevance between the productivity with net pressure and friction. The higher net pressure and fracture friction were,the more complexity the fracture would be and the more difficulty the fracture propagation would be. Then the productivity of coalbed methane wells would be low. The methods could provide the references to in-situ stress and production prediction after fracturing of coalbed methane wells.
出处
《煤炭科学技术》
CAS
北大核心
2017年第9期188-193,共6页
Coal Science and Technology
基金
中海石油(中国)有限公司资助项目(YXKY-2016-ZY-08
FQTFWQYZL-14-071)
关键词
煤层气井压裂
闭合压力
地应力
压降分析
注入摩阻
净压力
fracture of coalbecl methane well
closure pressure
in-situ stress
pressure decline analysis
fracture friction
net pressure
