Evaluation of coal reservoir coalbed methane production potential in considering different coal structures in a coal seam section: a case study of the Shizhuang North Block in the Qinshui Basin

Gas content and permeability are important parameters for the evaluation of coal reservoir gas production potential. When heterogeneity of these parameters is strong in a coal seam section, the results of any evaluation not considering the body of the coal structure and differences therein are quite different from reality. To this end, taking Shizhuang North Block 3# coal seam in Qinshui Basin as the research object, evaluation indices for CBM production potential considering different coal structure in a coal seam section were selected considering coalbed methane resource conditions, production power conditions, and removability conditions. Taking the geological strength index (GSI) as the link, the thickness, gas content, permeability, and brittleness index of different coal structures in a coal seam section were quantitatively characterized. Based on an analytical hierarchy process (AHP), a system for the evaluation of coal reservoir CBM production potential was constructed considering different coal structure in coal seam sections. The evaluation method was applied to Shizhuang north block in Qinshui Basin (Shanxi Province, China), and the results were compared with those obtained using the evaluation method without considering coal structure differences. The results show that when the heterogeneity of coal structure in a given coal seam section is strong, the evaluation of CBM production potential considering different coal structures can better reflect the objective facts, while in areas consisting of less heterogeneous coal structures, the results obtained using the proposed method differ slightly from those evaluated without considering such differences. The research findings provide a novel approach for accurately evaluating CBM production potential of coal reservoirs in areas consisting of highly heterogeneous coal structures.

Automated summary

The evaluation of CBM production potential considering different coal structures can better reflect the objective facts, especially in areas with strong heterogeneity in coal structure. The proposed method provides a novel approach to accurately evaluate CBM production potential in regions with highly heterogeneous coal structures.