Key technology and application of surface well drainage of coalbed methane in mining area of high gas mine

Abstract

The coalbed methane drainage with surface well, under the mining effects in a high gas coal mine has become increasingly important, especially for a complex region for the coalbed methane drainage. In contrast, due to the effects of coal mining, the surface wells are prone to deformation and damage. In this paper, a displacement and deformation model for the overlying strata was established. Three forms of deformation and failure of the surface well casing were proposed, such as shearing, stretching and uneven extrusion. Moreover, the mathematical model functions of “S” - type shear deformation, delamination tensile deformation and non-uniform extrusion for the surface well were established. In the ShanXi Coal Group YueCheng Mine, on the mining affected area surface well the coalbed methane drainage practice was conducted, producing a good coalbed methane drainage effect. YCCD-04 well without local protective device was deformed and damaged, and the dynamic deformation and failure process of surface well was detected by well imager; YCCD-02 well with local protective device has experienced mining and gas drainage effect is good, which verifies the effectiveness of local protective device. The YCCD-02 well coalbed methane drainage was 35 months in duration and the cumulative extraction of coalbed methane drainage volume was 1.3×107 m3. Simultaneously, the problem of gas control in the working face was solved, to ensure the safety of coal mining, achieving good social and economic effects.