Geological characteristics and exploration ideas of middle-low rank coalbed methane in Xinjiang Region: A case study of Liuhuanggou Block in southern Junggar Basin

The shallow coalbed methane resources above 2000 m in Xinjiang reach 7.51×10¹²m³, accounting for approximately 25.0% of the total coalbed methane resources in the China. In order to further clarify the geological characteristics and enrichment rules of coalbed methane resources in this area, taking the mid-to-low-rank coal seams in the Liuhuanggou block on the southern margin of the Junggar Basin as the research object, a comprehensive geological analysis of preliminary exploration data was carried out to further deepen the mid-to-low-rank coal seams in Xinjiang. The enrichment characteristics of coalbed methane clarify exploration ideas. This study has obtained the following three understandings and achievements: In the shallow exploration area dominated by medium-low rank coal seams, the structure is complex and the coal seam thickness is large. The single layer thickness of the coal seam in the target interval is greater than 10 m, the average porosity is 7.3 ~ 9.2%, and the average permeability is 2.4 ~ 2.64 mD. The gas content is quite different, ranging from 0.02 to 10.00 m³/t. The target layer is mainly biogenic coalbed methane, with shallow buried depth, strong hydrodynamic action, low gas content, as a result of unsatisfactory exploration and development. In the next step, the exploration of medium-low-rank coalbed methane in Xinjiang should fully combine the genetic type, structure, hydrogeology and burial depth conditions of coalbed methane, take gas content as the main reference index, and select relatively stable structures located in weak runoff-retention areas and areas with mixed and thermal origin of coalbed methane are the key to achieving commercial results.