华北地台石炭—二叠系煤成(层)气成藏地质单元划分

Division of geological unit of coal-derived (coalbed) methane accumulation in Carboniferous-Permian Huabei platform

华北地台石炭—二叠系烃源岩的生烃条件在区域上类似,但煤成(层)气藏的分布在区域上却不均衡。对华北地台石炭—二叠系煤成(层)气成藏地质单元进行了划分,将其划分为两个层次:成藏演化区和成藏波及域。依据烃源岩的埋藏史类型将成藏演化区划分为沉降—抬升剥蚀型成藏演化区和沉降—抬升剥蚀—再沉降型成藏演化区;依据切割石炭—二叠系煤系烃源岩的断裂(裂缝)的特征将华北地台上古生界煤成(层)气成藏波及域划分为层内波及域和层上波及域。建议从华北地台整体角度对该区石炭—二叠系不同成藏演化区和成藏波及域中煤成(层)气的富集机理进行研究。

In the Carboniferous-Permian Huabei platform, while hydrocarbon generating conditions of source rocks are similar in different regions, the distribution of coal-derived (coalbed) methane accumulations is imbalance in regions. The geologic unit of coal-derived (coalbed) methane accumulation in Carboniferous-Permian Huabei platform was divided by two levels: accumulation evolution zones and accumulation affecting areas. Accumulation evoluation zones are divided into subsidence - uplift denudation style and subsidence - uplift denudation - subsidence style according to buried history of carbonniferous-permian coal measure hydrocarbon source rock of Huabei platform, the former is mainly distributed in the Ordos basin, the latter mainly distributed in the Bohai Bay basin et al. Accumulation affecting areas are divided into inner layer and upper layer according to fracture characteristics of cutting Carbonniferous-Permian coal measure hydrocarbon source rock. The former which occurs in steady plot of Huabei platform mainly lies in Shaanbei slope of the Ordos basin, and the latter mainly lies in Haiyuan-Liupanshan-Baoji fracture belt of the western Ordos basin and Gubei fracture belt of Jiyang depression of the Bohai Bay basin and so on. It is suggested that enrichment mechanism of Carbonniferous-Permian coal-derived (coalbed) methane of the whole Huabei platform would be strengthened based on different accumulation evolution areas and accumulation affecting areas.