Solving hydrogeological parameters of Jurassic coal seam aquifer in Xiaojihan Coal Mine based on water inrush process

Wang Changshen; Chen Jiageng; Yin Wenbin; Yang Jiangfeng; Lü Jianhua; Zhang Hui

doi:10.19896/j.cnki.mtkj.2025.06.001

Abstract：When the well construction project of Xiaojihan Coal Mine in Yuheng Coalfield,Ordos Basin,approached and initially uncov-ered the upper No.2 coal seam of the Jurassic system,rare coal seam water inrush occurred continuously.The commissioned mine was classified as a medium-sized mine with hydrogeological type where the coal seam aquifer is the main direct water-filling source.Research on this specific type of aquifer and its associated water hazards is limited.To reveal the hydrogeological characteristics of such special a-quatic media,based on a water inrush process induced by the recent exposure of No.2 coal seam in Xiaojihan Coal Mine,hydrodynamic a-nalysis and analytical calculation methods were employed to study the hydrogeological parameter characteristics of coal seam aquifer.The results indicate that the water inrush process can be simultaneously generalized into a non-steady flow filling model centered around the water inrush point with a fixed drawdown,and a non-steady flow water level funnel expansion model with an average water inrush volume as an approximate constant flow rate.The hydraulic conductivity of the No.2 coal seam aquifer was determined to be 0.49-0.90 m/d,and the elastic storage coefficient was 4.25×10-3-8.03×10-3.Compared with the single-borehole steady flow pumping test during the explo-ration stage,the obtained hydraulic conductivity of the coal seam is approximately 10 times that of the pumping test results.The under-ground water inrush reveals the coal seam aquifer on a more realistic production scale and with a larger inrush volume.The obtained hy-draulic conductivity matches the mine water filling conditions,making the results more reliable.The coal seam water inrush is mainly a non-steady hydrodynamic process that consumes the stored water in the coal seam.In this case,the elastic storage coefficient is more important than the specific inflow rate.The research findings have addressed the deficiencies in water storage parameters of coal seam aquifers,providing crucial theoretical and technical supporting for guiding water hazard prevention during mine production stages,as well as for studying the types of mine water inflow in special aquifers and the mechanisms of special water hazards in the Ordos Basin.