Evaluation of the Geochemical Characteristics and Exploitation Potential of Produced Water from Coalbed Methane Wells in Eastern Yunnan, China

Abstract

Based on the analysis of the geochemical characteristics of the produced water from coalbed methane wells in eastern Yunnan, the effects of the water-rock interactions on the produced water were discussed, and the mining potential of each of the four wells was evaluated. The results show that with the increase in drainage time, the Na+ and Cl− concentrations decrease while the HCO−3 concentration increases. The produced water from the two wells in the Enhong Block shows D drift characteristics, while that of the two wells in the Laochang Block shows O drift characteristics. The order of the produced water affected by the surrounding rock is D-1 well > M-1 well > D-2 well > M-2 well, and the order of the produced water influenced by the coal seam is D-1 well > D-2 well > M-1 well > M-2 well. According to the variation in the As trace element concentration, it is inferred that in the four coalbed methane wells, the D-1 and D-2 wells have a greater exploitation potential than that of the M-1 and M-2 wells. On this basis, the influencing characterization parameters of the water-rock interactions on the produced water are established.