Quantitative Evaluation of Hydrocarbon-Generation Intensity of Coal-Measure Mudstones in the Shanxi Formation on the Eastern Margin of the Ordos Basin: A Case Study of the Daning–Jixian Area

Hydrocarbon-generation intensity (HGI) is a critical indicator for evaluating shale gas potential in source rocks. This study proposes a practical method to estimate HGI by integrating experimental pyrolysis data, EasyRo-based maturity transformation, kinetic modeling, and geological parameters. Using core samples from the Shanxi Formation in the eastern margin of the Ordos Basin, gold tube pyrolysis experiments were conducted under closed-system conditions to obtain gas yield data. The EasyRo model was applied to transform temperature to maturity, and a kinetic model was constructed to simulate hydrocarbon generation. Total organic carbon (TOC), maturity (Ro), thickness, and true density were used to calculate HGI at different depths. Spatial prediction of HGI was achieved using Kriging interpolation. Results indicate that although carbonaceous mudstones have higher TOC (14.2%) and gas yields (up to 155.84 mg/g TOC), black mudstones exhibit a 24.77% higher HGI due to greater thickness (average 67.2 m). This highlights the dominant role of formation thickness in controlling. Notably, black mudstones in the deeper western subregion exhibit greater gas-generation potential. These findings offer a robust quantitative basis for evaluating deep coal-measure shale gas resources in the Ordos Basin.