页岩气产能评价方法及模型研究

Shale Gas Productivity Evaluation and Model Study

非常规气藏渗流机理复杂,具有独特的渗流机理和生产动态特征,难以用常规的气井产能方法评价产能,预测可采储量。从渗流力学出发,根据页岩气藏压裂后储层特征,建立了页岩气藏复合模型,确定了页岩气井稳产时间,分析了内外区渗透率、内区半径、启动压力梯度、解吸压缩系数和储层厚度等影响规律;并参照Vogel方程建立了页岩气井产能方程。结果表明:内区渗透率、外区渗透率、内区半径、储层厚度和解吸压缩系数是影响页岩气井产能的敏感因素;表皮因子和启动压力梯度不是敏感因素。通过可靠性分析,参照Vogel方程建立的页岩气井产能公式能够快速、准确的判断页岩气井的产能。

The seepage mechanism of unconventional gas is very complex,and has a unique seepage mechanism and dynamic flow characteristics. It is difficult to use conventional gas production capacity to predict recoverable reserves. Starting from fluid mechanics,based on reservoir characteristics of the shale gas fracturing,a composite model of shale gas reservoirs was established,and stable production time was determined. The effects of inside and outside zone permeability,the radius,pressure gradient,desorption influence of the compression factor and reservoir thickness,etc. are analyzed,and the established a shale gas well productivity equation refer to Vogel equation. The results show that: area permeability,penetration outside the area,zone radius,reservoir thickness and desorption compression factor were sensitive to shale gas production capacity; skin factor and the pressure gradient is not sensitive factor; through reliability analysis,the productivity formula which was referred to Vogel equation can determine the production capacity of shale gas wells quickly and accurately.