Investigating Pyrite Content Impact on Multi-Frequency Dielectric Properties for Enhanced Hydrocarbon Detection in Low Resistivity Pay (LRP) Zones

Pyrite presence in hydrocarbons-rich formations creates a major obstacle for formation evaluation, as its conductive nature often causes conventional resistivity logs to fail in distinguishing hydrocarbons. To address this, this study investigates the effectiveness of multi-frequency dielectric measurements (4 MHz to 3 GHz) in accurately determining hydrocarbon saturation within low resistivity pay (LRP) zones. The research specifically examines how pyrite content affects complex permittivity behavior and evaluates whether high-frequency measurements can effectively bypass the electrical interference generated by these conductive minerals. Laboratory experiments were conducted using silica sand samples with precisely controlled additions of pyrite (up to 10 wt%). Four distinct experimental configurations were analyzed: fully brine-saturated sand, brine-saturated with pyrite, mixed brine-oil saturation without pyrite, and mixed saturation with pyrite. Dielectric properties (real permittivity and effective conductivity) were measured across a broad frequency range (4 MHz-3 GHz). Special attention was paid to maintaining consistent porosity, accurate fluid saturations, and temperature stability to ensure data integrity and reproducibility. Results demonstrate that pyrite dramatically influences electrical conductivity readings but has minimal effect on high-frequency dielectric permittivity. In fully brine-saturated samples, adding pyrite decreased overall conductivity, while in oil-bearing samples, it increased conductivity. Strong frequency dispersion was observed in mixed brine-oil systems, with interfacial polarization elevating effective permittivity and conductivity at lower frequencies that subsequently diminished at GHz frequencies. This frequency-selective influence confirms that high-frequency dielectric measurements can reliably estimate water saturation despite pyrite presence. The study validates that while pyrite confounds conventional resistivity interpretation, the dielectric permittivity at MHz-GHz frequencies remains a robust indicator of water volume, offering reliable hydrocarbon saturation estimation in LRP zones. Furthermore, frequency dispersion patterns highlight potential diagnostic features for fluid typing and wettability characterization.