Gas content is a key parameter for coalbed methane (CBM) resource evaluation and production potential assessment. The accurate prediction of gas content in deep coal reservoirs is more challenging than in shallow reservoirs because both adsorbed gas and free gas must be considered. In this study, continuous logging data from the deep No. 8 coal seam in the Daning–Jixian block were integrated with measured gas content-related parameters to construct a quantitative logging interpretation framework for deep CBM reservoirs. First, the relationships between logging parameters and Langmuir volume, Langmuir pressure, porosity, and water saturation were analyzed. Then, multiple linear regression models were established to predict these key intermediate parameters, which were subsequently used to calculate adsorbed gas, free gas, and total gas content. The model was further applied to the DJ 52 well area for spatial prediction. The results show that the total gas content ranges from 24.49 to 32.90 cm3/g. The high-gas-content area is mainly located in the north-central part of the study area, whereas the southern part shows relatively lower gas content, partly due to the influence of coal seam thickness and reservoir property heterogeneity. The proposed method provides an interpretable and practical approach for deep CBM gas content evaluation using logging data.
Li et al. (Thu,) studied this question.