沉积相和成岩作用对生物礁储层成因的控制研究

Control of sedimentary facies and diagenesis on genesis of reef reservoir

 徐维胜¹ 何川¹ 秦关 2

北京大学石油与天然气研究中心，北京 100871 怀俄明大学，美国 怀俄明 WY82071

上二叠统长兴组台地边缘生物礁之所以是普光气田的重要储集层，主要受到沉积相和成岩作用的控制，而碳酸盐岩台地沉积格局、造礁生物的广泛发育和有利的古气候条件是生物礁发育的前提条件。生物礁在海洋环境、地表暴露环境和埋藏环境中主要经历了胶结、压实、溶蚀、白云石化、重结晶等成岩作用的改造，导致了生物礁岩性和物性的巨大改变。生物礁石灰岩上部由于白云石化作用的改造，岩性由石灰岩转变成白云岩，从上往下呈现白云岩、灰质白云岩、白云质灰岩和石灰岩的岩性序列。胶结和压实作用极大地破坏了生物礁石灰岩的原生孔隙，而白云石化、溶蚀、重结晶作用的改造产生了大量的次生孔隙，成为重要的储集空间。

Platform edge reefs of Upper Permian in Changxing Formation are important reservoirs in Puguang Gas Field due to the controlling mechanism of sedimentary facies and diagenesis, but the depositional pattern, prosperity of reef-building organisms and favorable paleoclimates of carbonate platform are the predominant conditions for reef development. Altered by diagenesis of cementation, compaction, dolomitization, recrystallization and denudation in marine, exposure and burial environments, the lithological features and physical properties of reef have been severely changed, resulting in a vertical lithology sequence of dolomite to limestone interpolated by limy dolomite and dolomitic limestone. Though the primary porosities are destructed by cementation and compaction, a huge abundance of secondary porosities are created by dolomitization, recrystallization and denudation to serve as gas accumulation space.

10.6056/dkyqt201201012