中国东部页岩气藏与超压体系共生关系初探

Coexisting relationship between shale gas enrichment and over-pressure system in east China

超压影响着油气藏的形成和分布且是致密油气运聚成藏的重要动力源.通过类比国外超压页岩气盆地的实例,分析了中国东部断陷盆地古近系超压发育特征与湖相泥页岩分布特点及页岩气赋存条件,探讨了页岩气与超压体系的共生关系.渤海湾盆地古近系异常超压段往往和大套泥页岩层相对应,具备良好的页岩气成藏条件,研究发现其耦合机理在于有效气源岩发育和良好盖层条件导致的生烃增压机制为主导,最后总结指出超压存在是控制东部页岩油气富集的关键因素,并提出非常规油气勘探思路应有由外而内的转变即重点研究超压体系内部滞留成藏.

Abnormal fluid pressures are widespread throughout the global oil and gas basin.Overpressure plays a big role in tight reservoir accumulation.By comparing over-pressured shale gas basins abroad,pressure features and distribution characteristic of palaeogene lacustrine shale in east China rift basins are analyzed.The accumulation conditions of shale gas are studied and proved well in paleogene mud shales,Bohai bay basin.It is considered over-pressure during hydrocarbon generation maybe the main mechanism of coupling by discussing coexisting relationship between shale gas and pressure development.The over-pressure is the key element controlling eastern shale gas enrichment degree.The unconventional exploration evaluation thought should turn from outside to inside that is emphasizing pooling inner over-pressure system.