地应力对煤层气井水力压裂裂缝发育的影响  

Effect of crustal stress on hydraulic fracturing in coalbed methane wells

作　　者：唐书恒[1] 朱宝存[1] 颜志丰[2] 

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]河北工程大学资源学院,河北邯郸056038

出　　处：《煤炭学报》2011年第1期65-69,共5页Journal of China Coal Society

基　　金：国家科技重大专项课题(2008ZX05034-003);国家自然科学基金资助项目(40972108);国家863计划专题课题(2006AA06Z235);长江学者和创新团队发展计划(IRT0864)

摘　　要：以晋城矿区西部3号煤层的地应力及煤岩的力学性质数据为基础,采用数值模拟方法求解了不同地应力条件下井壁处及天然裂缝缝端的破裂压力,分析了地应力对水力压裂起裂压力、起裂位置的影响。研究发现:起裂压力和起裂位置不但与地应力方位有关,而且与地应力大小有关;随水平主应力差系数增大,天然裂缝与最大水平主应力间的夹角对破裂压力的影响程度增大。对于晋城矿区西部3号煤层,当水平主应力差系数大于0.84时,易产生较为平直的水力主缝;小于0.47时,易于产生网状裂缝;在0.47～0.84时,起裂方位与天然裂缝的分布有关。不同地区,用于判断起裂方位的水平主应力差系数不同。The crustal stress and mechanics properties data from No.3 coal seam in the western Jincheng mining area were analyzed.With a finite-element method,the formation fracture pressure at borehole walls and natural fracture tips under different conditions of crustal stress was calculated.The effect of crustal stress on initiation pressure and azimuth was calculated.Initiation pressure and azimuth are related with the magnitude and direction of crustal stress.The influence degree of the angle between a natural fracture and the maximum horizontal principal stress on fracture pressure increases with increasing principal stress difference coefficient.In No.3 coal seam in the western Jincheng mining area,hydraulic main fractures are easy to occur when the coefficient exceeds 0.84,net-like fractures are easy to occur when the coefficient is less than 0.47,and initiation azimuth is related with natural fracture distribution when the coefficient is between 0.47 and 0.84.In difference areas,the coefficient used to analyze the initiation azimuth is difference.

关 键 词：地应力 煤层气井 水力压裂 天然裂缝 破裂压力 起裂方位 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]