多孔介质中的趋肤效应特性分析OA

To clarify the regulatory mechanism of the skin effect in porous media under multiple influencing factors and address the resulting limitation on electromagnetic detection accuracy,a parametric digital rock model of porous media is developed using the COMSOL multiphysics simulation platform with its AC/DC module.This study systematically investigates the coupled influence of key factors such as porosity,water saturation,grain characteristics,electromagnetic parameters,and coil spacing on the apparent conductivity in induction logging.The validity of the research findings is confirmed through comparison with actual logging data from low-resistivity formations.The results indicate that:①In homogeneous formations,the skin effect is regulated by frequency and coil spacing;increasing either factor intensifies the effect,with the measurement range of the imaginary signal being more than three times larger than that of the real signal,and the real part approaching zero at the peak of the imaginary part.②The heterogeneous structure of porous media alters current paths and skin depth.A 10%increase in porosity expands the imaginary part of apparent conductivity by more than three times compared to the real part.Higher porosity,increased formation water salinity,or elevated water saturation exacerbates the skin effect.While the microstructure of grains affects response amplitude,it has no significant impact on the measurement range.③In low-resistivity reservoirs,the combination of high-salinity formation water and relatively high irreducible water saturation induces a strong skin effect,causing distortion and failure of the real signal.In contrast,the imaginary signal maintains an effective response across a wider measurement range.It is concluded that the skin effect in porous media is governed by the coupled interactions among pore structure,fluid distribution,and electromagnetic parameters.The imaginary signal effectively overcomes the measurement limitations of the real signal and enables accurate identification of oil,gas,and water layers in low-resistivity reservoirs.This study clarifies the regulatory mechanism of the skin effect in porous media,providing a robust theoretical foundation and practical reference for high-precision electromagnetic detection and log interpretation.