Unattached multiple layer superimposed coalbed methane system in Songhe mine, west Guizhou

From aspects of reservoir geology, sedimentary structure and hydrology, this paper has explored the vertical distribution of coalbed methane system of Longtan Formation in Songhe mine. The results show the regularity that ash and sulfur are high in the upper and the lower but low in the middle of the system. From the top to the bottom, the CBM content has the trend of rise-fall-rise. There are two sets of pressure systems in the correlation between the coal seam depth and the pressure coefficient. The three secondary sequences are highly consistent with the three lithologic sections which lay the physical property base of the systems. There is no hydraulic connection between the systems and the water abundance has the regularity of being weak-medium-weak which supply a hydrogeological base. The coal-bearing strata of Longtan Formation are an unattached multiple superimposed coalbed methane system which is jointly controlled by sedimentary, hydrogeological and structural conditions and can be divided into three unattached coalbed methane-bearing system. The research results provide geological basis for exploration development of the coalbed methane in Songhe mine.