Electromagnetic response prediction for conductive, permeable, heterogeneous steel-cased wells

Steel-cased wells can be used as galvanic sources to detect and estimate variations in subsurface electrical conductivity. Most of the modeling approaches are based on approximations to the casing and ignore the variations in magnetic permeability. In this paper, we investigate the impact of varying electrical conductivity and magnetic permeability on the electromagnetic response of steel-cased wells. As an example, we consider a full three-dimensional realistic representation of a steel-cased well in the surface-to-borehole and borehole-to-surface configurations. We show how the variable conductivity and permeability along the length of the casing can affect the electromagnetic measurements