TITLE:
Genesis Mechanism and Identification Methods of Low-Resistivity Oil Layers in Shahejie Formation of Bohai C Oilfield
AUTHORS:
Jianmin Zhang
KEYWORDS:
Low-Resistivity Oil Layer, Genesis Mechanism, Medium-Deep Formation, Irreducible Water Saturation, Additional Conductivity of Clay, NMR Logging
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.13 No.11,
October
30,
2025
ABSTRACT: The genesis mechanism of low-resistivity oil formation in the medium-deep Shahejie Formation of Bohai C Oilfield is unclear, and there is a lack of effective methods for identifying low-resistivity oil layers. This article conducts a comprehensive analysis based on core sample experiments, and research shows that the formation of low-resistivity oil layers in the oilfield is mainly caused by the superposition of three factors: 1) microcapillary development, high irreducible water; 2) additional conductive effect of clay; 3) deep invasion of high salinity mud filtrate. The low-resistivity oil layer in this oilfield is mainly characterized by high mud content and strong additional conductivity of clay, and the complex pore throat structure leads to high irreducible water saturation, and the impact of saline mud intrusion, resulted in low-resistivity oil layers. The oilfield is mainly a lightweight oil layer with hydrophilic wettability, studying the response characteristics of oil and water layers through core nuclear magnetic resonance experiments, effectively identifying low-resistivity oil layers based on the correlation between resistivity and physical properties.