Geothermal Exploration Magnetotellurics
Magnetotellurics is a passive electromagnetic geophysical exploration technique that uses natural electric fields from lightning sources, solar flares and ionospheric resonances to induce current flow in the ground. MT images the earth’s subsurface by measuring natural variations of electrical and magnetic fields at the Earth’s surface. Depth of investigation ranges from surface to 10,000m and beyond by recording higher frequencies with long-period sounding. Data are measured and converted to resistivity and then modeled to interpret the geology of the survey area in 3D.
Low frequency signals are generated from the interaction of solar wind with the earth’s magnetic field, while high frequency signals are created by worldwide thunderstorm activity (typically located near the equator.) The signals vary in strength over time (ie. hours, days, weeks) and both of these signal sources create time-varying electromagnetic waves. Longer MT measurements are required at each station in order to obtain high-quality data when exploring to greater depths.
How MT is used in Geothermal Exploration
Magnetotellurics is a non-invasive and environmentally conscious method for imaging the subsurface. Flexible and robust, it easily navigates obstacles other technologies face and can mobilise in any climate or location. The MT method is effective at mapping resistivity anomalies associated with geothermal structures including cap rock, faults and reservoir morphology. Generally speaking, rocks containing fluids such as water will have a low resistivity while dry and cold rocks will have high resistivities.
MT is Scalable
Spartan MT- anywhere, any weather!
Quantec offers worldwide coverage and availability with offices near key geothermal areas. We have completed numerous MT surveys all over the world, servicing client projects in Turkey, USA, Canada, Australia, Chile, Mexico and Africa (to name a few.)