煤储层渗透性核磁实验分析及测井评价

Nuclear magnetic resonance experimental analysis of coal reservoir permeability and well logging evaluation

针对目前测井方法很难精确评价煤储层渗透性的问题,在煤岩核磁共振实验和煤储层渗透率影响因素分析的基础上,建立了煤岩裂隙孔隙度与渗透率的相关关系,并借鉴常规储层电阻率测井方法评价了煤储层的裂隙孔隙度和渗透率,得到了评价本地区煤储层渗透率的有效方法。同时,针对研究区块,分析了煤体结构对渗透率的影响。研究结果表明:该地区煤岩核磁T2谱呈现明显的双峰形态,煤岩主要为吸附孔隙,但裂隙孔隙对渗透率的贡献更大;通过裂隙孔隙度计算渗透率的方法在研究区块应用效果较好;煤储层渗透率与煤体结构有着很好的对应关系,一般碎裂结构煤的渗透性好于原生结构煤。

Aimed at the problems of low accurate exist in current logging methods in evaluating the permeability of coal reservoirs, based on nuclear magnetic resonance （NMR） test and factors influencing coal reservoir permeability, the authors established the relationship between fracture porosity and permeability. Finally,they used conventional reservoir resistivity logging method to evaluate the fracture porosity and permeability of coal reservoir,and has obtained an effective method to evaluate the permeability of coal reservoir in this are-a. At the same time,this paper analyzed the influence of coal structure on permeability. The results show that the NMR T2 spectrum of the region is mainly bimodal, mainly adsorbed pore, but the contribution of fracture pore to permeability is larger. This method of calcu-lating the permeability through fracture porosity is very effective in the study block. Permeability of coal reservoirs has a good correspon-dence with coal structure, and the permeability of coal with fractured structure is better than that of primary structure coal.