Reservoir Geological Characteristics in the Middle Section of the Third Member of Shahejie Formation, Block S, Dongying Sag, Bohai Bay Basin

Abstract

The reservoir in the middle section of the third member of Shahejie formation in Block S is characterized by large burial depth, tight reservoir properties, and unclear oil-water distribution features. Through the implementation of zone division and correlation, 3D seismic interpretation, sedimentary facies identification and distribution analysis, as well as micro and macro reservoir descriptions, this paper systematically grasps oil-water distribution characteristics and hydrocarbon enrichment regularities, and clarifies the main controlling factors of hydrocarbon accumulation. The research results show that: ① Objective reservoir is divided into six units based on two control markers and two auxiliary markers, with main oil accumulation occurring in M3 and M4. ② Internal structures are characterized by westward-dipping monoclines sandwiched between southern and northern fault zones. Although the distribution of oil-bearing layers is not controlled by these structures within the area (as it is a lithological reservoir), fault zones outside the area play a role in sedimentation and hydrocarbon accumulation. ③ Reservoir system belongs to semi-deep lake-deep lake turbidite fan with deep burial depth, low porosity, low permeability. High-quality reservoirs are mainly distributed in turbidite channels. This study can provide reference for reservoir development in block S.