Experimental study and application of rock electrical properties under high temperature and high pressure based on Archie's formula: a case study of Jimsar shale oil reservoir in Xinjiang, China

This study conducted rock electrical experiments under high temperature and high-pressure conditions, combined with high-pressure mercury injection and nuclear magnetic resonance experiments to analyse the response characteristics of rock electrical parameters in shale oil reservoirs. The saturation index 'n' is positively correlated with increasing porosity and oil saturation, exponentially correlated with permeability logarithm, and negatively correlated with displacement pressure, according to experimental data. The formation factor decreases with porosity, permeability, average capillary radius, and pore throat homogeneity coefficient. Based on saturation index, formation factors, storage and seepage characteristics, and pore-throat structure, permeability and effective porosity were introduced, and two saturation correction models for high temperature and high-pressure rock electrical parameters were created. The model's general applicability shows that it calculates saturation more accurately than Archie's formula, with only 5% average difference from oil saturation. This study provides a more accurate and effective method for shale oil reservoir saturation interpretation. [Received: March 30, 2024; Accepted: August 16, 2024]