裂谷盆地致密砂岩气成藏机制与富集规律——以松辽盆地与渤海湾盆地为例

Mechanisms for gas accumulation and enrichment in tight sandstone reservoir in rift basins: Cases from the Songliao Basin and the Bohai Bay

裂谷盆地致密砂岩气是当前勘探的新领域,本文以松辽盆地与渤海湾盆地为重点,对裂谷盆地致密砂岩气成藏机制与富集规律进行了全面系统分析,明确了裂谷盆地有别于克拉通盆地的致密砂岩气气藏特征,指出裂谷盆地致密砂岩气成藏机制上表现为:多因素促源快速生气、多物源催生有利储层、长距离运移立体成藏,先致密后成藏有利配置。气藏富集规律上具有断槽控制气藏分布、沉积相带与构造带控制成藏、次生孔隙带与物性下限控制气藏富集段的特点。分析了松辽盆地与渤海湾盆地致密砂岩气勘探前景,明确了下一步勘探方向。

Tight sandstone gas in rift basins is a new play concept for exploration. This paper takes the Songliao Bbasin and the Bohai Bay Basin as case areas to systematically investigate the mechanisms for gas accumulation and enrichment in tight sandstones. The reservoir characteristics of tight sandstone gas in rift basins have been studied,which are different from those of craton basins. As to gas accumulation mechanism,it is demonstrated that multiple factors have accelerated the generation of gas by source rock,and multiple sediment provenance have ensured deposition of favorable reservoirs.Both the long gas migration distance and tightening of the reservoir before gas charge favors gas accumulation in multiple sections over large areas. For the enrichment controlling factors,it is concluded that the distribution of gas pools and source kitchens are located along the faulted troughs,the reservoir quality is controlled by facies and tectonic belts,while the vertical distribution of flowable gas sections is controlled by development of secondary porosity zones. Finally,the exploration potential and future exploration concepts of these two basins is analysed.