鄂尔多斯盆地侏罗系煤层气富集机制与模式

Enrichment mechanism and mode of Jurassic coalbed methane in Ordos Basin

基于煤层气富集与其形成的地质条件密切相关性,从大地热流与地温场、古构造应力场、地下水动力场等三场,阐述了鄂尔多斯盆地侏罗系煤层气富集的地质机制。研究认为,较低的地温为煤储层吸附甲烷提供了有利条件;古构造应力场与煤层裂隙的有机配置,对煤层气的富集比较有利;侏罗系含水层系统对煤层气的富集起到水动力封闭作用,在某些水动力较弱的近于滞流区,可能是煤层气富集的有利区带。同时认为鄂尔多斯盆地侏罗系煤层气藏属于典型的单斜构造富气模式,该模式下形成的煤层气富集特征受三场在内的各种能量场的相互耦合关系所制约。

Based on a closed correlativity between the enrichment and formation geological condition of the coalbed methane,from a terrestrial heat flow and geothermal field,palaeotectonic stress field and groundwater dynamic field,the paper stated the enrichment geologic mechanism of Jurassic coalbed methane in Ordos Basin.The study held that low ground thermal temperature could provide favorable conductions to the methane adsorption of coal reservoirs.An organic configuration between the palaeotectonic stress field and the seam fractures would favorable to the enrichment of coalbed methane.The Jurassic aquifer system could play a hydrodynamic sealing role to the enrichment of coalbed methane and some nearly stagnation zone with weak hydrodynamics could be favorable zone of the coalbed methane enrichment.The paper held that the Jurassic coalbed methane formation in Ordos Basin was a typical enrichment mode of the monoclinal structure and the enrichment features of coalbed methane under the mode were restricted by the mutual coupling relationship of each energy field within the geothermal field,hydrodynamics field and tectonic stress field.