In-situ Stress Field of Fanzhuang Coabed Methane Block in Qinshui Basin

Abstract

Geostress is a crucial factor that affects the in-situ permeability and reservoir stimulation, and thus the performance of coalbed methane (CBM) recovery from coal. Therefore, a systematically investigation of in-situ geostress was made based on pressure-time records of the hydraulic fracturing of 238 CBM wells collected from Fanzhuang block in Qinshui Basin of China. The results indicate the vertical stress, maximum and the minimum horizontal principal stress range from 5.92 to 20.08 MPa, 8.03 to 41.75 MPa and 5.38 to 21.24 MPa, respectively. The gradient of the maximum horizontal stress and least horizontal stress vary from 14.16 to 77.82 kPa/m and from 11.12 to 41.43 kPa/m in respective. The relatively high horizontal principal stress zone concentrates in the NE trending within the middle of the block, while the relatively low-stress zone distributes in west, east and south of the block. The analysis of the microseismic fracture monitoring from 72 CBM wells shows that the orientation of the maximum horizontal principal stress concentrates in the NEE∼NE direction and locally distorted by the faults, which can be further used to optimize the CBM well drilling, completion and stimulation in the studied area.