The dipole mapping method

In the bipole-dipole mapping method, a current field is set up by the use of a bipole current source. The current field is then studied by making measurements of electric field intensity with dipole receivers at many locations around the bipole source. The values for electric field intensity may be used to compute apparent resistivities if we assume that the earth is uniform or to compute apparent conductance if we assume that the earth resembles a conducting sheet. Maps of apparent resistivity values or apparent conductance values may be interpreted by comparing them with similar maps computed analytically for various simplified earth models. The bipole-dipole mapping method is useful mainly in locating areas where ground resistivity varies rapidly in the horizontal direction. It has found application mainly in exploration for geothermal reservoirs but also has been used for mining exploration and engineering studies, and an example of each is described.