中国致密大气田成藏特征分析——以鄂尔多斯盆地和四川盆地为例

Analysis on Accumulation Characteristics of China's Tight Gas Field——Take the Ordos Basin and Sichuan Basin as Examples

致密砂岩气是最早进行勘探开发的非常规资源之一,且储量巨大。文章通过大量文献调研资料对各个盆地的致密气藏生、储、盖、圈、运、保等成藏条件及成藏机理进行综合研究与总结分析,研究分析表明中国致密大气田具有源储纵向叠置,大面积分布,广覆式生烃等特点。烃源岩以煤系源岩为主,有机质成熟度高,生烃产生的异常超压提供气体运移聚集成藏动力来源,运移方式以非达西渗滤、扩散方式为主;气藏气水关系复杂,没有统一的气水界面,准连续充注、近源成藏,后期历经改造等。

Tight sand stone gas is one of the earliest unconventional resources for exploration and development,and its reserves are huge.Based on a large number of literature research data,this paper makes a comprehensive study and analysis of the formation conditions and mechanism of tight gas reservoirs in various basins,such as generation,storage,cap,circle,transportation and preservation,taking the Ordos basin and Sichuan basin as examples.The study shows that China’s tight gas field has the characteristics of vertical superposition of source and reservoir,large area distribution,and extensive hydrocarbon generation.The source rocks are mainly composed of coal-measure source rocks with high organic maturity.The abnormal overpressure generated by hydrocarbon generation provides the power source of gas migration and accumulation,and the migration mode is mainly non-darcy filtration and diffusion.The relationship of gas pool and air-water is complex.There is no uniform soda interface,quasi-continuous filling,near-source reservoir formation,and can be reformed on later,etc.