Key Geological Controls to Formation of Coalbed Methane Reservoirs in Southern Qinshui Basin of China: I, Hydrogeological Conditions

摘要

The coal-bearing series in the Qinshui basin, which is underlay by the Middle Ordovician, is mainly composed of the Upper Carboniferous Taiyuan Formation and Lower Permian Shanxi Formation. In this paper, the hydraulic interrelation and hydrous characteristics between the aquifers in the three set strata were analyzed, the water and gas transmissibility of the hydrogeological units and boundary faults was investigated, and the matched correlation of the groundwater isopotential surface to the CBM accumulation was discussed. It was then indicated that the local accumulation of the coalbed methane in the area studied is mainly controlled by the slow or stagnant runoff of the groundwater, which has been highly confirmed by the hydro-geochemical field of the groundwater.