沁水盆地南部煤层气成藏动力学机制研究

Study on the Coalbed Methane Reservoir-Forming Dynamic Mechanism in the Southern Qinshui Basin, Shanxi

应用油气成藏动力学方法,研究沁水盆地南部煤层气成藏动力学机制。通过热力场、应力场、地下水动力场的分析,认为本区具有良好的生烃条件和储集条件,晋城矿区南部,地下水流场为一种汇流区,这种地下水流场特征,导致煤层气在汇流区域得到富集,形成地下水和煤储层中流体的能量的积聚,这种能量的聚集是形成高压储层的基础和保证。同时,南部还是低地应力分布区,渗透率相对地高,因此南部煤层气富集,煤层气产能大,是煤层气勘探开发最有利地区。晋城矿区北部为单向流动的地下水动力场,使得在相同地质背景下的同一地区出现不同的煤层气成藏特征。

This paper deals with the application of the method of petroleum reservoir-forming dynamics in the study of the coalbed methane reservoir-forming dynamic mechanism in the southern Qinshui Basin. On the basis of an analysis of the thermodynamic field, stress field and hydrodynamic field, the authors suggest that there are favorable conditions of hydrocarbon generation and accumulation in the area. The groundwater hydrodynamic field in the southern part of the Jincheng mining district is a catchment area. The existence of such a groundwater hydrodynamic field led to the concentration of coalbed methane and accumulation of energy of groundwater and fluid in coalbeds. The accumulation of such energy is the basis and guarantee for the formation of high-pressure reservoirs. This part is also characterized by lower stress and higher permeability and thus is rich in coalbed methane and has a high coalbed methane productivity. So it is the most favorable area for coalbed methane exploration and development. But there is a groundwater hydrodynamic field with an unidirectional flow in the northern part of the Jincheng mining district. Thus there appear different coalbed methane reservoir-forming characteristics in the same area under the same geologic setting.