关键词: 砂质碎屑流, 近端水道沉积, 沉积模式, 中三叠世, 广西百色利周地区

Abstract:

Based on the data of cores, thin sections and mercury penetration, this paper studied the characteristics of sedimentary facies, petrology, properties and genesis of low permeability reservoir of the first member of Fuyi Formation in Gaoyou Sag by using statistics and correlation method. The results show that the reservoir of the first member of Fuyi Formation formed in subaqueous distributary channel and mouth bar. The reservoir rock is mainly composed of fine grained feldspathic sandstone and feldspathic litharenite, they were poorly sorted, with high content of cements, and both the compositional maturity and textural maturity are low. The reservoir properties are poor, with low porosity and permeability. The pore types are mainly intergranular dissolved pores, followed by intragranular dissolved pores and mold pores. The main reservoir space is secondary pores. Deposition is the fundamental factor for causing the low permeability of the reservoir, and cementation and strong compaction are the main factors for the low permeability. Because of the strong cementation during the early formation of reservoir, relatively weak dissolution in later period and more developmental carbonate cementation during the late diagenetic stage, the characteristics of low permeability reservoir is significant.

Key words: sandy debris flow, proximal channel deposit, depositional model, Middle Triassic, Lizhou area