Electromagnetic monitoring of fluid injection - lessons learned

GeoCat; 74874Magnetotelluric data acquired over the Paralana project has provided valuable insight into the resistivity distribution across geothermal sedimentary basins. The time-lapse MT measurements during an EGS fluid injection trace the preferential fluid connection in a NNE direction aligned with the regional stress field. The results add information to existing micro-seismic measurements by providing the preferential fluid-filled fracture connection at depth. New results using 2D forward magnetotelluric anisotropy codes are able to reproduce the direction of enhanced fluid flow by fitting measured against modelled phase tensor residuals. Future surveys will need to address limited resolution issues between EM measurements from the surface compared to standard micro-seismic monitoring techniques.S. Thiel, J.R. Peacock, J. MacFarlane and G. Heinso