我国煤层气分布赋存主控地质因素与富集模式

Main Geological Controls on Distribution and Occurence and Enrichment Patterns of Coalbed Methane in China

我国煤层气分布和富集受多种地质因素控制,就煤层含气性主控地质因素的地质构造条件、煤层埋藏深度、水文地质条件、沉积环境、煤层物性和岩浆活动等6个方面进行了系统研究。结果显示构造沉降作用、水力封堵和水力封闭控气作用、逆断层以及向斜核部有利于煤层气赋存;构造抬升作用、水力运移逸散作用、正断层、背斜核部以及陷落柱不利于煤层气赋存;随煤层埋深增加,煤层气吸附量逐渐增加,临界埋深之后吸附量开始降低;煤层顶、底板厚度越大,岩性越致密,越有利于煤层气保存;煤层气含量与煤厚呈正相关性。根据各地质因素的影响程度,煤层气分布赋存可概括为"多因素综合控制"和"多因素影响、某一两个因素主控"2种类型。

The distribution and enrichment of coalbed methane(CBM) are controlled by multiple geological factors in china,which including geological tectonic,coal burial depth,hydrogeological condition,sedimentary environment,coal physical properties and magmatic intrusion.The results show that,tectonic subsidence,hydraulic sealing and hydraulic jam-up processes,reverse fault,and syncline axis are beneficial for CBM preservation;tectonic uplift,hydraulic migration-escape process,normal fault,anticline axis,and collapse column are unfavorable factors for preserving CBM.With increasing coal burial depth,content increases but subsequently decreases starting at critical burial depth.The CBM can be more easily preserved within coals,which developing thicker and tighter roof and floor.The CBM content is positively related to coal thickness.According to the effect degree of the geological factors,the law of CBM distribution and enrichment can be summarized as comprehensively controlled by multiple factors and influenced by multiple factors,primarily controlled by one or two factors.