Three-Dimensional Geological Modeling of Coal Seams in a Mining Face Using Cross-Layer Gas Drainage Boreholes: Method and Application

To address the limited number and insufficient spatial control of surface exploration boreholes in coal mining faces, as well as the difficulty in directly using densely distributed cross-layer gas drainage boreholes for three-dimensional geological modeling, 10,881 cross-layer gas drainage boreholes from the S1301 working face of Wangfeng Coal Mine were investigated. A modeling workflow integrating automated data preprocessing, data quality control based on physical consistency constraints and local spatial jump detection, directional variogram analysis, anisotropic ordinary kriging, and constrained Delaunay triangulation was developed. The results showed that 10,103 valid samples were obtained within the modeling boundary, of which 957 were identified as anomalous, corresponding to an anomaly rate of 9.47%. After quality control, 9,691, 9,767, and 9,636 effective control points were retained for the coal-seam roof, floor, and true thickness, respectively. The principal and secondary correlation directions of the coal-seam interfaces were 111° and 21°, respectively, with an anisotropy ratio of 3.00. The RMSEs of the validation sets for the coal-seam roof, floor, and true thickness were 2.022, 1.789, and 0.992 m, respectively. Profile validation using three roadways yielded MAEs of 0.285, 0.246, and 0.261 m for the roof, floor, and coal-seam thickness, respectively, and the modeled profiles were generally consistent with the measured profiles. The results indicate that data quality control can effectively reduce the spatial propagation of anomalous points, while anisotropy constraints can preserve the directional continuity of the coal-seam roof and floor interfaces. The established model can effectively characterize the spatial undulations and thickness variations of the No. 3 coal seam, providing a methodological reference for the reuse of geological information from cross-layer gas drainage boreholes and fine three-dimensional geological modeling of coal seams in mining faces.