The controlled source electromagnetic (CSEM) method, also called sea bed logging, is a mostly
offshore geophysical technique, employing electromagnetic
remote-sensing
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth ...
technology to map the electric resistivity distribution of the subsurface. The electrical resistivity helps to discriminate between different types of rocks. CSEM is mostly used to indicate the presence and extent of
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...
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.
2006 - mCSEM Marine Controlled Source Electromagnetic
See also
*Exploration geophysics
Exploration geophysics is an applied branch of geophysics and economic geology, which uses physical methods at the surface of the Earth, such as seismic, gravitational, magnetic, electrical and electromagnetic, to measure the physical properties o ...
* Electromagnetic Geoservices ASA
*WesternGeco
WesternGeco is a geophysical services company. It is headquartered in Schlumberger House on the property of London Gatwick Airport in Crawley, West Sussex.
__NOTOC__
Background
The company provides reservoir imaging, monitoring, and development ...
* List of oilfield service companies
This is a list of oilfield service companies – which provide services to the petroleum exploration and production industry but do not typically produce petroleum. In the list, notable subsidiary companies and divisions are listed as sub-lists o ...
References
Economic geology
Petroleum geology
Remote sensing
{{remote-sensing-stub