Applying 3D geological modeling to predict favorable areas for coalbed methane accumulation: a case study in the Qinshui Basin

Qinshui Basin possesses enormous deep coalbed methane (CBM) resources. Fine and quantitative description of coal reservoirs is critical for achieving efficient exploration and development of deep CBM. This study proposes a 3D geological modeling workflow that integrates three parts: geological data analysis, 3D geological modeling, and application of the model, which can accurately predict the favorable areas of CBM. Taking the Yushe-Wuxiang Block within the Qinshui Basin as a case study, lithology identification, sequence stratigraphy division, structural interpretation is conducted by integrating well logging, seismic, and drilling data. Six lithology types and regional structural characteristics of the Carboniferous-Permian coal-bearing strata are finely identified. Combining experimental testing on porosity and gas content and well testing on permeability, a 3D geological model that integrates the structural model, facies model, and property model was established. Utilizing this model, the total CBM resource volume in the study area was calculated to be 2481.3 × 10⁸ m³. Furthermore, the model is applied to predict the distribution ranges of four types of CBM favorable areas. The workflow is helpful to optimize well deployment and improve CBM resource evaluation, ultimately provide theoretical guidance for subsequent efficient exploration and development. Our study constitutes a reference case for assessing potential of CBM in other blocks due to the successful integration of multiple available of data and its practical applications.