新的煤层气藏物质平衡方程及其储量计算方法

A New Material Balance Equation for Coal Bed Gas Reservoir and Reserve Estimation

在煤层气藏开采过程中,当水排出煤体并伴随压力下降时,吸附气解吸以及溶解态水溶气析出,造成游离气空间体积变大。目前国内外学者在推导煤层气藏物质平衡方程过程中只考虑吸附气、游离气,但都忽略水中溶解气的影响。为此,在考虑水中溶解气的前提下,从物质体积守恒原理出发,系统全面地推导出煤层气藏物质平衡方程。通过实例分析验证了该方程的适用性和可靠性,同时认识到水溶气对计算天然气储量有一定的贡献。

During the development of coal bed gas reservoir, as water is discharged from the coal mass and pressure declines, gas dissolved in water is precipitated and adsorbed gas is desorbed, which make free gas space larger. Currently scholars at home and abroad in the derivation process of the material balance equation for coal bed gas reservoir take absorbed gas, free gas into consideration, but all neglect the effect of gas dissolved in water. So under the premise of considering gas dissolved in water this paper systematically and thoroughly deduces a new ma terial balance equation for coal bed gas reservoir according to material balance principle. A case study verifies the applicability and reliability of this equation, at the same time we recognize that solution gas in water makes a certain contribution to the calculation of gas reserve.