元坝长兴组超深层生物礁大气田优质储层发育机理

Developing mechanism for high quality reef reservoir( Changxing Formation) buried in ultra-depth in the big Yuanba Gas Field

通过系统开展元坝气田长兴组超深层生物礁储层岩石学与岩石地球化学分析,结合碳酸盐岩溶蚀动力学模拟实验,以及储层古压力恢复,揭示了元坝超深层生物礁优质储层的发育保存机理。研究表明,早期暴露溶蚀、浅埋藏白云岩化是基质孔隙发育的基础,储层深埋引起的古油藏原油裂解导致的超压水力破裂缝的形成,是储层渗透性改善的关键,"孔-缝耦合"共同控制了超深层优质储层的发育。在此基础上,构建了生物礁非均质"孔-缝双元结构"储层模型,为生物礁储层预测奠定了理论基础。

The formation and preservation mechanism of ultra-deep burial high quality hydrocarbon reef reservoirs in Changxing Formation of Yuanba Gas Field were revealed by the systematically analysis of reservoir petrology and geochemistry, combined with dynamic simulation of carbonate corrosion and reservoir historical pressure recovery. The results show that early surficial corrosion and shallow burial dolomitization are the basic diagenesis of matrix porosity development. The overpressure generation hydraulic fractures, which formed by the cracking of deep-buried oil in paleo-reservoirs, are the key of reservoir permeability development. Pore-fracture coupling controls the formation of ultra-deep burial high quality reservoir. Based on the results of this study, a heterogeneous ＂pore-fracture dualistic structure＂ model of reef reservoirs was constructed, which provided the theoretical foundation for reef reservoir prediction.