太原西山煤田古交区块煤层气成藏地质单因素分析

Single factor analysis of CBM reservoir forming geology in Gujiao block of Taiyuan Xishan coalfield

为了分析太原西山煤田古交区块内影响煤层气成藏的地质因素,本文从含煤岩系地层分析入手,讨论了煤储层顶底板岩性与厚度、煤层厚度、煤岩煤质、煤化程度、储层埋深、区域构造热事件以及地质构造与煤层气成藏之间的关系。研究结果表明,煤层顶底板厚度与储层气含量不具有明显的相关性;气含量与煤储层厚度呈正相关,与煤中灰分、挥发分和水分含量呈负相关。含煤岩系煤储层至少经历了三次生烃高峰,煤层热演化是影响煤层气生成量的主控因素;区内主体向斜和正断层的断裂构造是控气的主要原因。研究区煤层气成藏主要受控于煤化作用与构造特征,同时受煤储层埋藏深度和煤层厚度影响,是多种因素影响下综合作用的结果。

To analyze the geological influence factors of coalbed methane （CBM） reservoir forming in Gujiao block of Taiyuan Xishan coalfield, the author discussed the relationships between the CBM reservoir forming and thickness and lithology of coal reservoir roof and floor, thickness of coal seam, constituents of coal, coal rank, burial depth of coal seam, regional structure thermalevent, geologic structure. The research results showed that there was no significant correlation between the thickness of roof and floor and CBM content of the reservoir; the CBM content was positively correlated with the thickness of coal reservoir, while was negatively correlated with the content of ash, volatiles and moisture content in coals. In addition, the coal seams had experienced at least three periods of hydrocarbon generation by thermal pyrolysis, and the thermal evolution was the main control ling factor in the CBM generation; syncline and normal fault in the area were the main reason of CBM control. The CBM reservoir forming in the Gujiao block was mainly influenced by coal coalification and tectonic characteristics, as well as many other integrated factors, such as the buried depth and thickness of coal seam.