A Study on the Controlling Effect of Geological Structures on Coalbed Methane Occurrence in the Northeast Margin of Qinshui Basin, North China

This study investigated the patterns of gas occurrence in the coal seam structural zones of the northeastern margin of the Qinshui Basin, with a focus on the Sijiazhuang Coal Mine. Using laboratory experiments, theoretical analysis, and field exploration, we examined how geological structures influence gas distribution. The results show that gas content and pressure near normal faults are generally higher than those in reverse fault areas. However, fault-induced gas occurrence is complex, with stress superposition potentially reversing this trend. When a normal fault intersects modern tectonic stress at a perpendicular or large angle, the fault zone may transition to a compressional state, enhancing gas preservation. Fold structures were found to play a significant role in gas distribution, with anticline zones exhibiting the highest gas content, followed by syncline and normal zones. Collapse columns were shown to affect gas occurrence within a range of 15 to 180 m, with the impact depending on factors such as surrounding rock properties, hydrogeological conditions, and fault activity during collapse formation. Additionally, mirror-like sliding surfaces, formed by multiple factors, are prevalent in the coal seam structures of this region. These sliding surfaces are closely linked to structural zones and serve as valuable indicators for geological predictions in coal seam development.