太原西山区块煤储层地应力分布特征及评价

地应力是影响煤层气开发的关键参数，为了分析太原西山区块煤储层地应力条件，为煤层气勘探开发提供理论依据，采用水力压裂法测量地应力，统计了太原西山区块35口井煤储层地应力资料，获取二叠系山西组2号煤储层地应力与煤层埋深之间的相关关系，阐明了现今地应力分布特征。结果表明，研究区山西组2号煤层破裂压力梯度、闭合压力梯度和煤储层压力梯度的平均值分别为4.77 MPa/hm、2.82 MPa/hm和0.6 MPa/hm；2号煤层最小水平主应力梯度、最大水平主应力梯度和垂直主应力梯度的平均值分别为2.82 MPa/hm、3.24 MPa/hm和2.7 MPa/hm。主应力均随煤层埋深增加呈线性规律增高。根据最小水平主应力的大小，将研究区划分为低应力区、中应力区、高应力区3个区。 

Distribution and evaluation of geostress in coal reservoirs in Xishan block,Taiyuan

Geostress is a key parameter affecting the development of coalbed methane, in order to analyze the geostress conditions of Xishan coal reservoir in Taiyuan and provide theoretical basis for exploration and development of coalbed methane, the geostress was measured by hydraulic fracturing, the geostress data of 35 coal reservoirs in Taiyuan Xishan mining area were statistically analyzed, the correlations and their models between geostress of No.2 coal seam in Permian Shanxi Formation and the burial depth of coal seam were established, and the present geostress conditions and controlling mechanism were clarified. The results show that the average value of the fracture pressure gradients, closure pressure gradients and coal reservoir pressure gradients of No.2 coal seam in the study area are 4.77 MPa/hm, 2.82 MPa/hm, 0.6 MPa/hm respectively. The average value of the minimum horizontal principal stress gradients, the horizontal principal stress gradients and vertical principal stress gradients are 2.82 MPa/hm, 3.24 MPa/hm and 2.7 MPa/hm, respectively. The principal stress increased linearly with the burial depth. According to the minimum horizontal principal stress, the study area was divided into low stress zone, moderate stress zone and high stress zone, and the stress state of each zone was defined.