Induced Polarization in Rocks

Abstract

Phenomena bearing on the passage of direct current through a rock as a multi-phase medium may be divided into two categories, depending upon the time duration of their appearance. The first category includes processes involved in the rapid change in current from one constant level to another (see Fig. 55). The second category includes the residual electric field observed in rocks when a field is removed. This latter phenomenon is used in exploration geophysics, and has been called induced polarization. Before proceeding to a consideration of polarization phenomena in rocks, we will characterize briefly some of the basic phenomena that take place in dielectrics, which may be considered under certain conditions as the elements of most natural formations.