Hydrochemical characteristics and significance of coalbed water and coalbed methane well–produced water in the Suzhou mining area

The hydrogeochemical characteristics of the mining area are of great significance for coalbed methane (CBM) production. Based on experimental test data for coalbed water and CBM well-produced water in the Suzhou mining area, as well as the actual production capacity of CBM wells, the effect of the hydrogeochemical characteristics on CBM well production capacity was analyzed in this article. The results indicated that the groundwater in the study area was in a closed hydrological environment and that the water quality type was mainly Na-K-HCO₃. When the groundwater from QD coal mine flowed through coal seam 6, the exchange intensity between Na⁺ and K⁺ in the water and Ca²⁺ and Mg²⁺in the formation's minerals was relatively high. The coefficients of variation of the ions in the QD coal seam water were within a moderate range, and the coefficients of variation of Ca²⁺ and Mg²⁺ were much higher than those of the other ions. Within the same coal mining area, the HCO₃^- concentration of the water produced from the CBM wells was positively correlated with the production of CBM. Among them, the HCO₃^- concentration of the water produced from well N-3 was the highest, and the gas production of this well was also the highest.