Monitoring Electrical Properties of Rocks in Target Zone of CO2-Sequestration Site

Abstract

We address evaluation of resistivity of a target zone of a CO2-sequestration site using a simple measurement made from inside metal-cased boreholes. An approximate analytic expression is derived for the admittance measured between two metal casings in a stratified formation. It is shown that in a highly conductive environment measurement electrodes should be positioned inside the target depth range. Charts and plots are produced for evaluation of the admittance as function of the inter-casing separation and gas saturation in the target layer. The results indicate the possibility of monitoring the target zone using metal-cased borehole separated by distances of several hundreds meters.