Study on major geologic factors influencing coalbed methane enrichment in south Yanchuan Block

In order to find out the main influencing factors of coal seam gas content, analysis method of mathematical statistics and analogy were used. Five factor s for evaluating the coal seam gas content were the type of structure, coal seam thickness, burial depth of the coal seam, maceral and hydrogeologic condition. The stu dy shows that the coal seam gas content is mainly affected by the burial depth of the coal seam, the hydrogeologic conditions and the minor faults. The deeper the buri al depth is and the weaker the hydrodynamic conditions for preserving the coalbed methane are, the higher is the coalbed gas content. A stronger hydrodynamic conditi on and lttle fault are unfavorable for the preservation of coalbed gas, resulting in a large quantity of coalbed methane dissipation. It is concluded that the southwest an d northwest areas of the block are the enrichment regions, resulting in a gas content greater than 15 m3/t. The gas content northeast of the block is below 10 m3/t.