Analysis of Influencing Factors and Sensitivity Characteristics of Coal Electrical Conductivity Based on the Digital Core Technology

ABSTRACT

Coal electrical conductivity is a key physical parameter during the coalbed resources exploration and development. Conventional petrophysical experiments face challenges in studying coal electrical conductivity due to its insufficient resolution and coal's brittle nature. The recently developed digital core technology provides a novel approach to characterize coal resistivity by coupling with various influencing factors. In this study, a multi‐modal data fusion strategy was first developed to construct a three‐dimensional (3D) digital coal‐rock model by integrating micro‐computed tomography (micro‐CT) imaging, MaipSCAN mineral analysis data and laboratory porosity measurements. The lattice Boltzmann method was subsequently employed to characterize the distributions of movable hydrocarbons and water within coal pores. Using finite element simulations coupled with a controlled variable method, we systematically investigated the effects of intrinsic and extrinsic factors on coal resistivity. Furthermore, the sensitivity of each factor was quantitatively evaluated using the Morris screening method. Our study reveals that under the same metamorphic grade, the effects of different factors on coal resistivity exhibit significant variations depending on pore structure development and fluid occurrence states. The relationship between coal resistivity and variations in matrix porosity and water saturation demonstrates a staged correlation in coal seams with underdeveloped cleat fractures. Formation water salinity and clay CEC follow power‐exponential relationships with resistivity reduction, whereas clay content and temperature exhibit linear dependencies. Clay minerals and pore fluids exhibit a dynamic competitive relationship in their contributions to coal conductivity, which conforms to parallel conduction principles. Sensitivity analysis revealed that the descending order of influencing factors is water saturation, matrix porosity, clay mineral content, clay CEC, temperature and formation water salinity, indicating that the coal resistivity is more significantly influenced by intrinsic factors than by extrinsic factors. These results can provide essential theoretical insights for optimizing coal resource exploration strategies and reservoir evaluation protocols.