Abstract:

Two-phase proximal turbidite fans are developed in the 3^rd member of Shahejie Formation in Wuhaozhuang area,eastern Zhanhua depression,and they form the major pay zones in the lower sub-member of the 3^rd member.The fan is mainly composed of conglomerate,glutenite and dark mudstone and shale,in which the sandsone is low in both compositional maturity and textural maturity.The major genetic types of sandbodies are gravel-rich main channel sandstone,sand-rich midfan braided channel fill,and midfan front lakes with mixed sand/mud.Sandbodies of different types are different depositional and textural characteristics and reservoir properties.The braided channel sandbodies have a better poroperm characteristics than that of the gravel-rich main channel sandstone and midfan front lobes,and serve as the main reservoirs with its mean porosity of 13.1%～13.5% and mean permeability of 0.87×10^-3～5.95×10^-3μm².The reservoir properties also vary tremendously between the upper and lower fans with the former having better poroperm characteristics but thinner net sands and smaller oil-bearing area while the latter having average physical properties but thicker net sands and bigger oil-bearing area.It is suggested that better gradation of sandbodies means better poroperm characteristics,sandbody architectures control the reservoir properties through exerting influences upon the lateral continuity and vertical connectivity of the reservoirs,and diagenesis influences the growth of reservoir pores.

Key words: reservoir property, sedimentary characteristics, turbidite fan, the 3^rd member of Shahejie Formation, Zhanhua depression