Magnetotelluric Monitoring of Geothermal Fluid Flow

Abstract

Monitoring fluid flow in enhanced geothermal systems (EGS) is vital to reservoir growth and production. Geothermal fluids are innately conductive due to high temperature and pressure and dissolved enhanced ion concentration. This can be exploited by geophysical measurements sensitive to subsurface conductivity changes at several hundreds of meters to a few kilometers depth, such as magnetotellurics (MT). It is proposed that fluid flow can be monitored by measuring subsurface conductivity as a function of space and time using the magnetotelluric method constrained by other geophysical and geological data. 3D MT forward modelling studies demonstrate the feasibility of the method. MT data will be collected in the near future across the EGS site at Paralana, South Australia.