考虑水溶气的煤层气物质平衡方程推导及应用

Derivation and Application of Material Balance Equation of Coalbed Methane Containing Dissolved Gas

煤层气属非常规天然气,煤层气藏没有明显的气水界面,地层水填充在煤岩裂缝和基质中,在一定的温度和压力条件下,地层水中常含有丰富的水溶气。在前人对煤层气研究的基础上,考虑地层水中溶解气的影响,建立了新的物质平衡方程。将该物质平衡方程线性化,给出了累计产气量的预测方程和煤层气中平均含水饱和度的计算方法。计算结果表明,当考虑地层水溶解气时,计算得出的煤层气原始地质储量高于不含溶解气时原始地质储量。通过实例分析验证了该方程的可靠性,据此可以定量地确认地层水中的溶解气对天然气储量的影响。

Coalbed methane is unconventional gas.Coalbed methane gas reservoir without obvious water interface,coal fracture and matrix is full filled with water,under temperature and pressure conditions,often rich water-soluble gas resources are accompanied by formation water.On the basis of previous research,this paper considers additional impact of dissolved gas from formation water,and established a new material balance equation.Further more,linearization the material balance equation and putting forward the average water saturation calculation method and cumulative coalbed methane production prediction equation,finally,getting the result that the material balance equation which considered water-soluble gas in coalbed methane gas is higher than that of not consider.Testing the reliability of the equation through real case,it can recognize the impact of dissolved gas form formation water to the nature gas in place quantitatively.