A parametric study of the vertical electric source

Measurement of the vertical magnetic field caused by a vertical electric source (VES) is an attractive exploration option because the measured response is caused by only 2-D and 3-D structures. The absence of a host response markedly increases the detectability of confined structures. In addition, the VES configuration offers advantages such as alleviating masking resulting from conductive overburden and the option of having a source functioning in a collapsed borehole. Applications of the VES, as in mineral exploration, seafloor exploration, and process monitoring such as enhanced oil recovery, are varied, but we limit this study to a classic mining problem—the location of a confined, conductive target at depth in the vicinity of a borehole. By analyzing the electromagnetic responses of a thin, vertical prism, a horizontal slab and an equidimensional body, we investigate the resolving capabilities, identify survey design problems, and provide interpretational insight for vertical magnetic field responses...