This study investigates the impact of varying pore throat constriction in 3D straight channels on the electrical conductivity of fluid-filled, clay-containing porous rocks through simulation. The research identifies a critical ratio of clay conductance to fluid conductance that dictates the regime of electrical conductance behaviour. A non-linear increase in electrical conductance is observed when the clay-to-fluid conductance ratio exceeds the critical ratio, whereas a linear relationship is maintained below this critical ratio. A modified form of Archie’s law relating effective conductivity and porosity has been proposed for the clay coated channels.