Abstract:

Finding out the hydrogeological conditions and it’s controlling gas effects of CBM（coalbed methane） development area is important, which can provide a foundation for further development well location deployment. Taking the No.15 coal seam of Songta Block in Shouyang area as a research object, the conventional ion of the produced water in 11 coalbed methane wells has been tested, and the mineralization and ion distribution characteristics of the produced water are obtained. According to the Sulin classification, the types of produced water are divided. And according to the dynamic liquid level height at the initial stage of drainage of coalbed methane wells and combined with the elevation of coalbed floor, the equivalent water level of each coalbed methane well is calculated. On this basis, the hydrodynamic field in studying area are divided into stagnant area, weak runoff area and runoff area. Meanwhile, the controlling gas effects of hydrogeological parameters on gas content of No.15 coal seam are analyzed from the aspects of perspective of hydrochemistry and hydrodynamics. The results show that the main types of water quality in the studying area are NaHCO₃ and CaCl₂. The runoff area, weak runoff area and stagnant area are successively distributed from north to south. For some areas, when the sodium chloride coefficient is less than 1.04, the desulfation coefficient is less than 0.12, and the carbonate balance coefficient is less than 10.39, the gas content is more than 12 m³/t. These areas are beneficiation areas in coalbed methane. The hydrodynamic conditions of hydrodynamic sealing type and hydrodynamic plugging type are conducive to the enrichment of coalbed methane. The hydraulic escape type leads to the decrease of coalbed methane gas content. The research results provide a reference for the optimization, exploration and development of CBM enrichment areas in the study area.

Key words: hydrogeology, ion characteristic, hydrochemical parameter, controlling gas effect, Shouyang area