Time-lapse magnetotelluric monitoring of an enhanced geothermal system

摘要: ABSTRACTRealization of enhanced geothermal systems (EGSs) prescribes the need for novel methods to monitor subsurface fracture connectivity and fluid distribution. Magnetotellurics (MT) is a passive electromagnetic (EM) method sensitive electrical conductivity contrasts as function depth, specifically hot saline fluids in resistive porous media. In July 2011, an EGS injection at 3.6-km depth near Paralana, South Australia, was monitored by comparing repeated MT surveys before after hydraulic stimulation. An observable coherent change above measurement error response present causal, that variations phase predict apparent resistivity. Phase tensor residuals proved most useful representation characterizing alterations resistivity structure, whereas aided determining sign amplitude variations. These two representations residual suggested migrat...