The Relation Between Resistivity and Temperature in the Basaltic Crust of Iceland

Abstract

The ability of resistivity measurements to provide information on the temperature distribution in the uppermost crust is vital for geothermal exploration. During the past few years effort has been made within various projects and by many researchers to understand the resistivity properties of basaltic rocks and how it is affected by temperature. These efforts cover various types of laboratory measurements of core samples including measurements at in situ conditions for high temperature fields. In this paper we review the past results of laboratory data and validate some of the results by applying them to real field data where logged boreholes and resistivity models from TEM and MT measurements are available. We predict, and show example, that a typical low temperature field in Iceland should produce a low resistivity anomaly at shallow depth but a high resistivity anomaly deeper in the reservoir. The main results of this paper are, however, that the laboratory measurements of resistivity of rock samples at in-situ conditions are crucial to draw conclusions about geothermal reservoir properties from resistivity soundings.