煤化度对煤层气成藏特性影响规律的研究

Influence law of coalification degree on coal bed methane characteristics

综述了煤层气的成因类型和成气过程的研究现状,说明生物成因和热成因是煤层气的2种主要成因类型,且煤层气生成过程以热成因为主,生物成因为辅。通过分析不同煤化度煤层气的生成过程,说明在整个煤化作用过程中煤层气的生成大致经历了4个阶段,即由植物遗体转化为泥炭阶段、褐煤转型阶段、长焰煤～瘦煤转化阶段以及贫煤～无烟煤阶段。从煤化度角度阐述了不同煤化度煤层气的贮藏特性,即不同煤化度煤层气存在较大差异,特别是不同煤层气吸附、解吸特征的差异影响了其吸附成藏、解吸、渗流及产出的整个过程;煤吸附CH4的能力随着煤化度的增加呈现先急剧增加后缓慢减小的趋势。最后分析了不同煤化度煤层气存在成藏差异的原因,说明煤化学结构、煤物理结构以及成煤过程中地质条件的差异是导致不同煤化度煤层气富集成藏差异性的主要原因。

The research of genetic types and formation of coal bed methane indicates that,there are two main genetic types,biogenesis and hydrothermal origin,the former is dominant while the second one is minor.The formation process of coal bed methane with different coalification degree show that it＇s composed of about four steps,such as the plants remains translate into peat stage,the lignite transition stage,from long flame coal to lean coal conversion stage,and the lean coal to anthracite stage.The storage characteristics of different coalification degree coal bed methane is elaborated from the coalification degree,that means,there are large differences among coal bed methane with different coalification degree.Especially the adsorption,desorption characteristics of coal bed methane effect the adsorption,desorption,reservoir seepage and the outputs of the whole process.The capacity of coal adsorption methane first increase dramatically,then decrease slowly with the increase of coalification degree.analyse the cause of accumulation difference of different coalification degree coal bed methane,which illustrate that the difference of the coal chemistry structural,coal physical structure and the geological conditions in the form of process of coal are the main reason to lead to the accumulation difference of different coalification degree.