【摘要】 根据震源机制解分析得出太原西山煤田的区域构造应力场特征,在此基础上,基于有限元分析法对煤田内部2号和8号煤层的地应力分布进行了模拟,并结合煤层水力压裂资料获得验证。综合分析结果显示:与山西地堑系的构造背景一致,西山煤田的构造作用以NW—NNW向的近水平拉张作用为主;2号煤层和8号煤层的地应力分布趋势基本一致,均由四周向内部逐渐增大,2号煤层的水平地应力值介于12.4~39.4 MPa,8号煤层的地应力值介于12.6~38.3 MPa,与水力压裂测量结果的相对误差小于20%,受煤层埋深的影响,8号煤层的地应力整体上高于2号煤层;相同地质构造背景的约束下,两个煤层的应力方向分布基本一致,主应力(拉张力)的方向均以NW和NNW向为主,与水力压裂测量和震源机制解结果基本吻合。拉张构造应力作用下,有利于更多还原

【Abstract】 The regional tectonic stress field of Xishan coalfield was obtained according to focal mechanism solutions.On this basis,the geo-stress distribution of Coal Seam2 and Coal Seam8 was simulated through finite element analysis and verified by coal-seam hydraulic fracturing data.Comprehensive analysis results have indicated that the tectonism of Xishan coalfield is dominated by NWNNW approximate horizontal tension effect,which is consistent with the tectonic settings of Shanxi graben system;the geo-stress distribution trend of Coal Seam2 was basically consistent with that of Coal Seam8,where both stresses were increased inwards from the periphery.The horizontal geo-stress values of Coal Seam2 and Coal Seam8 are ranged in12.4-39.4 MPa and12.6-38.3 MPa respectively.These values have relative deviations less than 20% against hydraulic fracturing measurements.Influenced by the burial depth of coal seam,the geo-stress of Coal Seam8 is overall higher than that of Coal Seam2.Constrained by the same tectonic settings,the distribution of both stress directions is basically the same.Moreover,the directions of both principle stresses(tensions)are dominated by NW and NNW respectively,basically identical to the hydraulic fracturing measurements and focal mechanism solutions.The tensile stress effect is able to promote the generation of coal-seam fissures and improve the permeability,but prone to the loss of coalbed methane.Therefore,the focus should be put on finding favorable reservoir blocks in the exploration process of CBM.更多还原