Electrical Methods for Deep Subsurface Exploration

A theoretical study has been made of the transmission of electrical signals through the earth in order to devise the most promising methods for determining the electrical resistance of deeplying formations. It was found that the most effective technique is one which apparently has not been previously proposed. Theoretical analysis indicates this new method can provide a fairly accurate measurement of the variation in subsurface resistance at depths of interest in explorations for petroleum reservoirs and other deep-seated mineral deposits. Field tests carried out in the western part of Kern County, Calif., show that the results obtained by this method are in good agreement with the electrical resistive logs obtained from drilled wells.