Controlled source electro-magnetic
Encyclopedia
The Controlled Source Electromagnetic (CSEM) method is an offshore
geophysical technique , employing electromagnetic remote-sensing
technology to indicate the presence and extent of hydrocarbon
accumulations below the seabed.
The CSEM survey uses a dipole source that is towed just above the seafloor to transmit a time-varying electromagnetic field into the earth. This field is modified by the presence of subsurface resistive layers and these changes are detected and logged by an array of receivers placed on the seabed. Because hydrocarbon-bearing formations are highly resistive compared with surrounding formations, a CSEM survey can indicate the presence of oil and gas in offshore situations.
Offshore (hydrocarbons)
"Offshore", when used relative to hydrocarbons, refers to an oil, natural gas or condensate field that is under the sea, or to activities or operations carried out in relation to such a field...
geophysical technique , employing electromagnetic remote-sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
technology to indicate the presence and extent of hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
accumulations below the seabed.
The CSEM survey uses a dipole source that is towed just above the seafloor to transmit a time-varying electromagnetic field into the earth. This field is modified by the presence of subsurface resistive layers and these changes are detected and logged by an array of receivers placed on the seabed. Because hydrocarbon-bearing formations are highly resistive compared with surrounding formations, a CSEM survey can indicate the presence of oil and gas in offshore situations.
See also
- Exploration geophysicsExploration geophysicsExploration geophysics is the applied branch of geophysics which uses surface methods to measure the physical properties of the subsurface Earth, in order to detect or infer the presence and position of ore minerals, hydrocarbons, geothermal reservoirs, groundwater reservoirs, and other geological...
- WesternGecoWesternGecoWesternGeco is a geophysical services company. It is headquartered in the Schlumberger House on the property of London Gatwick Airport in Crawley, West Sussex, in Greater London.-Background:...
- Electromagnetic Geoservices ASAElectromagnetic Geoservices' or ' is a Norwegian geophysical company using proprietary marine electromagnetic technology to support oil and gas companies in their search for offshore hydrocarbons....