沁水盆地煤地质与煤层气聚集单元特征研究

Research on the Coal Geology and Characteristics of Coalbed Methane Accumulation Units in Qinshui Basin

通过对沁水盆地煤层气聚集单元分析,可以看出煤层气聚集单元划分需要查明影响煤层气成藏的各种地质因素。煤层气聚集成藏是天然气成藏中的特殊情况,其特殊的成因机制使得聚集单元分析不能套用常规石油天然气聚集单元的划分原则,其中煤地质基础研究特别是煤层气基础研究是煤层气聚集单元分析的基础;对于一个完整盆地,煤聚积规律研究对煤层气最为重要,因此应该在高分辨率层序地层单元划分的基础上进行精细的富煤单元分析;对于指导煤层气勘探与开发,盆地内部次级单元的划分是实用的,也是难度更大的;沁水盆地煤层气聚集单元可以用以下"富气区"描述,即沁南极富气区、东翼斜坡带富气区、西翼斜坡带低富气区、西山较低富气区和高平-晋城低富气区,因此沁南区是煤层气成藏有利区。

Through the analysis of accumulation unit of coalbed methane in Qinshui Basin, it is shown that the classification of the coalbed methane accumulation units requires all the geological factors influencing the coalbed methane reservoiring to be found out. Coalbed methane accumulating and reservoiring are a special case of natural gas reservoiring, and its specific reservoiring mechanism makes that the principle of classifying normal natural gas accumulation units cannot be used to the accumulation unit analysis of coalbed methane reservoir. Of which, the fundamental research of coal geology,especially, coalbed methane geology is the basis for analyzing coalbed methane accumulation units.The research on coal accumulating law in terms of a whole basin is most important for coalbed methane study; Therefore,the detailed analysis of coal-rich unit should be carried out based on high-resolution classification of sequence stratigraphic units. The classification of sub-units of coalbed methane accumulation within the basin is practical and much more difficult in the light of coalbed methane exploration and exploitation. The coalbed methane accumulation units in Qinshui Basin can be described as follows: the south extremely gas-rich district, the east wing slop gas-rich district, the west wing slop weak gas-rich district, Xishan weak gas-rich district and Gaoping-Jincheng weak gas-rich district. The south district of the basin is favorable for coalbed methane reservoir formation.