Some Studies on The Electromagnetic Field Response of Conducting Bodies in the Induction Method of Prospecting

Abstract

The present work embodies the results of mainly experimental and partly theoretical studies of some problems relating to the electromagnetic induction method of prospecting. After introducing the subject of geophysical exploration of mineral deposits by the induction method and the purpose leading to the present investigation are outlined. Then the principles of electromagnetic modeling are explained and design details of the Amplitude phase meter built for the model studies, together with details on the overall experimental arrangement and the measurement over scale models of conducting are bodies of various shapes aphere, plate and diss- in the uniform field inside a loop, in the field of an infinite line and in the field of vertical magnetic dipole, are presented and discussed. It is then explained how these results may be used to prepare 'type' curves of electromagnetic response and form characteristics rules for the aforementioned cases. These may be utilized to interpret field data in terms of location, depth, dip, shape, size and conductivity of the ore bodies. The effect of surrounding host rooks, which has been ignored so far is then evaluated by approximate theoretical techniques. The problems of electromagnetic response of a conducting sphere buried in a conducting half space in the field of a loop and in the filed of linear cable are analytical solved under some simplifying results an attempt is made to outline how field data in induction surveys may be interpreted when the presence of host rocks cannot be ignored.