Cross‐borehole delineation of a conductive ore deposit in a resistive host—experimental design

The finite‐difference time‐domain method is used for high‐resolution full‐wave analysis of cross‐borehole electromagnetic surveys of buried nickel sulfide deposits. The method is validated against analytical methods for simple cases, but is shown to be a valuable tool for analysis of complicated geological structures such as faulted or layered regions. The magnetic fields generated by a wire loop in a borehole near a nickel sulfide deposit are presented for several cases. The full‐wave solution is obtained up to 200 MHz, where quasi‐static methods would have failed. The dielectric response is included in the solution, and the diffractive nature of the field is observed. The sensitivity of each receiver in a vertical line in the cross borehole is presented and analyzed to provide an optimal weighting for receivers that can be applied to an experimental study.