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Controlled Source Electromagnetic (CSEM) methods are powerful geophysical techniques designed for mineral and hydrocarbon exploration, relying on the use of artificially generated electromagnetic fields to probe subsurface conductivity variations. In this approach, a controlled source—typically a grounded dipole or a towed transmitter—injects electromagnetic energy into the earth, and receivers placed on the surface or seabed measure the resulting field responses. Because different geological formations and fluid contents exhibit distinct electrical conductivities, CSEM surveys can effectively distinguish between resistive bodies such as hydrocarbon reservoirs and conductive backgrounds like saline water or clay-rich sediments. The method is particularly valuable in offshore hydrocarbon exploration, where it complements seismic surveys by reducing ambiguity in reservoir characterization. For mineral exploration, CSEM helps detect massive sulfide deposits and other conductive ore bodies. By combining advanced instrumentation, precise field procedures, and sophisticated modelling, controlled source electromagnetic methods provide a reliable means of mapping subsurface resources, enhancing exploration efficiency, and reducing drilling risks.
This lecture is part of GPH 312 ELECTRICAL AND ELECTROMAGNETIC PROSPECTING METHODS in the Geophysics department. The course has 30 recorded lectures across 10 series, all free to watch. Read or download the GPH 312 lecture note to study alongside the video.