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From Thule to Huli's:
Use of Magnetotellurics in Difficult Acquisition Areas
Christopherson,
Karen Rae
Chinook Geoconsulting, Inc., Evergreen CO
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Recent applications of Magnetotellurics
have produced results superior to those of earlier years by many
improvements in the technology, the application and the interpretation
of the method. MT continues to be useful in those areas where seismic
acquisition is either difficult or expensive, where the surface inhibits
effective seismic penetration, or where the use of MT is cost-effective
as a predecessor to seismic.
Improvements made to MT within the last few years include: multi-site
acquisition with varied station spacings and omni-directional, low
frequency antennae; smaller, higher storage field computers, sensor-box
modifications for filtering unwanted signal (such as lightning);
post-acquisition re-processing of the data via robust schemes; and
faster, larger 2-D and 3-D modeling capabilities.
Within the last two years, MT has been used world-wide for a variety of
exploration targets. These include the continued use of MT for mapping
sub-carbonate plays in Papua New Guinea with on-going drilling. Here,
use of seismic is precluded due to thick, high-velocity surface
limestone. MT has been used as a precursor to seismic in overthrust
regimes in Nevada and Colorado where MT is used to highgrade areas as
prospects before seismic programs are acquired. In Greenland, MT has
been used for reconnaissance mapping in large basin environments
sub-basalt.
On-going system modifications are being made to provide larger channel
systems and future marine acquisition of MT.
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