Hydraulic fracture initiation theory for a horizontal well in a coal seam  

作　　者：Hou Bing Chen Mian Wang Zheng Yuan Jianbo Liu Ming 

机构地区：[1]State Key Laboratory of Petroleum Resource and Prospecting,China University of Petroleum [2]Security Department,Tuha Oil Company

出　　处：《Petroleum Science》2013年第2期219-225,共7页石油科学（英文版）

基　　金：the financial support from the National Natural Science Foundation of China(No.51204195,No.51074171 and No.51274216)

摘　　要：A series of experiments were pertbrmed to determine rock mechanical parameters related to hydraulic fracturing of coal. The effect of confining pressure and pore pressure on the strength of coal was stt, died. Experimental results show that the coal seam in the study areas has a relatively low elastic modulus, high Poisson＇s ratio, high fragility and is easily broken and compressed. The coal seam is considered as a transversely isotropic medium, since the physical properties in the direction of bedding plane and orthogonal to the bedding plane vary markedly. Based on the generalized plane strain model, stress distribution for an arbitrarily orientated wellbore in the coal seam was determined. In a horizontal well, hydraulic fracturing was lbund to initiate in the coal seam mass due to tensile failure, or from cleats due to shear or tensile failure. For those coal seams with abundant natural cleats, hydraulic fracture initiation can be induced by any of these mechanisms. In this study, hydraulic fracture initiation criteria tbr a horizontal well in a coal seam were established.A series of experiments were pertbrmed to determine rock mechanical parameters related to hydraulic fracturing of coal. The effect of confining pressure and pore pressure on the strength of coal was stt, died. Experimental results show that the coal seam in the study areas has a relatively low elastic modulus, high Poisson＇s ratio, high fragility and is easily broken and compressed. The coal seam is considered as a transversely isotropic medium, since the physical properties in the direction of bedding plane and orthogonal to the bedding plane vary markedly. Based on the generalized plane strain model, stress distribution for an arbitrarily orientated wellbore in the coal seam was determined. In a horizontal well, hydraulic fracturing was lbund to initiate in the coal seam mass due to tensile failure, or from cleats due to shear or tensile failure. For those coal seams with abundant natural cleats, hydraulic fracture initiation can be induced by any of these mechanisms. In this study, hydraulic fracture initiation criteria tbr a horizontal well in a coal seam were established.

关 键 词：Hydraulic fracturing coal seam transversely isotropic fracture initiation CLEAT naturalfracture 

分 类 号：TD315[矿业工程—矿井建设]