水力封堵型煤层气藏判识条件分析

Identification Condition Analysis of Coalbed Methane Reservoir plugging off by Hydrodynamic Force

从宏观和微观两个方面分析了不同条件下煤层气的赋存特征,总结出水力封堵型煤层气藏的判识条件。研究表明,宏观上,可以通过煤储层边界的物理性质进行判识,在煤储层与地下水连通的基础上,分析断层、岩性、地下水三者之间的组合对水力封堵型煤层气藏赋存所起的作用,将水力封堵型煤层气藏划分为地层-水力封堵型、开放性断层-水力封堵型、封闭性断层-水力封堵型、岩性-水力封堵型、开放性断层-岩性-水力封堵型五种类型;微观上,主要通过煤储层流体的化学性质来判识,包括水的矿化度、水化学类型、甲烷碳同位素等三个方面,通常水力封堵型煤层气藏的地层水矿化度低于1 000mg/L,甲烷碳同位素较轻,且水化学类型为NaHCO3型、Na2SO4型或为NaHCO3和Na2SO4混合型。

In order to conclude the identification conditions of coalbed methane reservoir plugging off by hydrodynamic force,this article has analyzed the occurrence characteristics of CBM under different conditions both macroscopically and microscopically.The research shows that,a coalbed methane reservoir could be identified through physical properties of coalbed reservoir boundary macroscopically.Based on the connection between groundwater and coalbed reservoir as well as the effects of combination relationships among the fault,lithology and groundwater,coalbed methane reservoirs plugging off by hydrodynamic force could be classified into 5 types,namely the strata,open fault,close fault,lithology and open fault-lithology plugging off types.On the other hand,the chemical properties of the coalbed reservoir fluid,including the water salinity,water chemical type and methane carbon isotope also could be regarded as the identification conditions.The water salinity is generally less than 1000mg/L and the methane carbon isotope is lighter while the water chemical type is NaHCO3,Na2SO4 or the compound of them.