Changes

  | part    = Predicting the occurrence of oil and gas traps

  | part    = Predicting the occurrence of oil and gas traps

  | chapter = Applying magnetotellurics

  | chapter = Applying magnetotellurics

  | frompg  = 16-1

  | frompg  = 16-4

  | topg    = 16-12

  | topg    = 16-4

  | author  = Arnie Ostrander

  | author  = Arnie Ostrander

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch16/ch16.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch16/ch16.htm

  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

}}

}}

Magnetotellurics (MT) is an electrical geophysical technique that measures the resistivity of the subsurface. Although MT cannot provide the resolution of [[Seismic data|seismic surveys]], it is less expensive and, more importantly, can be used in places where seismic data collection is impractical or gives poor results. This is the same physical parameter that is measured in a borehole resis- tivity log.

Magnetotellurics (MT) is an electrical geophysical technique that measures the [[Electrical_methods#Electrical_properties_of_materials|resistivity]] of the subsurface. Although MT cannot provide the resolution of [[Seismic data|seismic surveys]], it is less expensive and, more importantly, can be used in places where seismic data collection is impractical or gives poor results. This is the same physical parameter that is measured in a borehole [[Basic_open_hole_tools#Resistivity|resistivity log]].

==How magnetotellurics differs from electric logs==

==How magnetotellurics differs from electric logs==

==Subsurface layers resolved==

==Subsurface layers resolved==

Subsurface layers are resolved by inverse modeling of MT data acquired across a spec- trum of frequencies, as illustrated in [[:file:Applying-magnetotellurics fig16-1.png|Figure 1]].

Subsurface layers are resolved by inverse modeling of MT data acquired across a spectrum of frequencies, as illustrated in [[:file:Applying-magnetotellurics fig16-1.png|Figure 1]].

==Magnetotellurics resolution==

==Magnetotellurics resolution==

The rule-of-thumb for MT resolution for depth of burial vs. layer thickness is 10:1. For example, to “see” a layer at a depth of 1,500 m (5,000 ft), the thickness of the layer needs to be approximately 150 m (500 ft) or more. Low-resistivity layers are more easily delineated than high-resistivity layers. It is difficult for MT to resolve more than three or four subsurface layers.

The rule of thumb for MT resolution of depth of burial vs. layer thickness is 10:1. For example, to “see” a layer at a depth of 1,500 m (5,000 ft), the thickness of the layer needs to be approximately 150 m (500 ft) or more. Low-resistivity layers are more easily delineated than high-resistivity layers. It is difficult for MT to resolve more than three or four subsurface layers.

==See also==

==See also==

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Applying magnetotellurics]]

[[Category:Applying magnetotellurics]]