Coalbed methane development effect and geological evaluation under large inclination angle geological coupling condition

The southern margin of Junggar Basin is an important area for the production of medium and low-rank CBM resources in China. Typical characteristics, such as multiple coal seams, large dip angle (LDA), low thermal evolution and thick coal seams, are the key considerations for further exploration and development. Aiming at the problem of optimizing the selection parameters of the selected area under the constraints of high dip angle complex geological conditions, this paper analyzes the productivity construction demonstration area in the southern Urumqi River East-Dahuangshan area,and discusses the factors affecting the productivity of medium and low coal rank coalbed methane wells under large dip angle geological coupling conditions. It is found that the effect of single factors affecting the productivity of high-inclination coal seamsis often limited. Under the constraints of geological coupling, the matching relationship of various geological parameters and the reasonable implementation of engineering countermeasures are the keys to determine the high and stable production of coalbed methane wells. Therefore, three comprehensive factors that control the productivity of CBM were summarized: resource occurrence conditions, key elements of gas reservoirs, and development technical countermeasures, and combined the status quo of exploration and development, evaluation parameters with strong adaptability were determined. In addition, in view of the problem that the evaluation criteria of low-rank CBM resource selection were not clarified in the current selection evaluation process, fuzzy mathematical clustering analysis method was used to deeply analyze the logical relationship between the attribute values of the same index of coal seams in different regions and quantitatively establish standards applicable to this evaluation, such as gas content, thermal evolution, multi-coal combination coefficient. Finally, analytic hierarchy process (AHP)was used to evaluate the potential of CBM resources in the west of Urumqi river.The results showed that the development potential was ranked in order from large to small: western area of Urumqi river, Hutubi area and Liuhuanggou area.