Seismic and Electromagnetic Study of Reservoir Properties for Geothermal Applications

Abstract

Joint reflection seismic, resistivity and multi-fold ground-penetrating radar (MFGPR) study of reservoir analogues allows extracting information about cross-property relations of interest in the characterization and monitoring of deep geothermal resources. In particular, a link between resistivity and velocity of seismic waves can be established though porosity. MFGPR is further used as a structural and physical properties validation tool, as it provides ultra-high resolution images of the rock volume, including networks of joints and fractures, estimates of electromagnetic impedance and detailed mapping of variations in electromagnetic properties that affect amplitude and velocity and are highlighted by the attributes of the radar trace. Comparison between experimental results, theoretical and empirical cross-property relations connecting electrical conductivity to elastic moduli and velocities of rocks shows that combined methods provide enhanced assessment of reservoir characteristics, with particular reference to porosity. We test the method on a Tertiary limestone outcrop.