Abstract: A method for sensing a condition of a hydrocarbon reservoir from a subterranean well having a lined section with a liner and an unlined section includes attaching an electric current sensor to the liner proximate to a lower end of the lined section and a plurality of electromagnetic sources located along the unlined section. The electromagnetic sources are activated independently and the resulting current induced in the liner by each electromagnetic source is measured with the electric current sensor. These measurements can be inverted to determine the spatial distribution of the electric conductivity within the reservoir and its changes in time due to fluid substitution during production. Alternatively, a fast and robust method for interpretation of the data is presented for early detection and location of a possible water front approaching the production well.

Abstract: A method for sensing a condition of a hydrocarbon reservoir from a subterranean well having a lined section with a liner and an unlined section includes attaching an electric current sensor to the liner proximate to a lower end of the lined section and a plurality of electromagnetic sources located along the unlined section. The electromagnetic sources are activated independently and the resulting current induced in the liner by each electromagnetic source is measured with the electric current sensor. These measurements can be inverted to determine the spatial distribution of the electric conductivity within the reservoir and its changes in time due to fluid substitution during production. Alternatively, a fast and robust method for interpretation of the data is presented for early detection and location of a possible water front approaching the production well.