Super- HRAM (Helicopter) Data
Example 2 – Shallow channel detection
Certain surficial deposits and forms will give rise to magnetic
anomalies. In western Canada, glacial material (and reworked products) derived from the Canadian
Shield and their reworked products often has a higher magnetic
susceptibility than the underlying bedrock. Where these deposits are
contained within a defined landform, such as a paleo-channel or esker,
they will give rise to a measurable magnetic anomaly. Tertiary and
Quaternary buried channels, i.e. those with little or no surface
expression, are important for hydrocarbon exploration. Super-HRAM (and
HRAM) surveys have been successful in detecting buried channels in a
highly cost-effective manner.
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 Example of residual magnetic
image, highlighting several channels of Tertiary/Quaternary age. The
image shows several northward draining fluvial channels that terminate at
a larger, approximately east-west-trending channel. Also imaged by the
magnetic data is a pipeline (dotted pattern in the lower half of image)
and individual wells, industrial plant etc. (‘bull’s-eyes’ scattered
throughout the image). The main channel is approximately 2000m wide,
whereas the tributaries are 300-400m wide. None of the channels have a
current surface expression.
[click to enlarge]
For more information on this example see our
publications.
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As well as magnetic detection, the shallow channels are often detected
using electromagnetic (EM) surveying methods. Magnetic and EM sensors are combined on the
Fugro Resolve© system. This system was test-flown in an area of shallow
gas production.
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Example of collecting joint EM and magnetic data for shallow channel
detection. The image on the left is resistivity at 400Hz, and image on
the right is residual magnetic intensity.
[click to enlarge]
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The data shows that the channels can be identified in the
EM-resistivity image by their higher resistivity values (greens and
blues), which contrasts with the more conductive bedrock shales (reds).
In the magnetic image, the contact between the bedrock and in-filling
valley material is defined by a strong dipole magnetic anomaly, with the
positive peak on the side of the more magnetic material (glacial drift in
the valley). Additional magnetic anomalies within the limits of the
channel either represent changes in the magnetic properties of the fill
material and/or ‘terracing’ within the valley profile. The results show
that both the EM and magnetic datasets can be used to define the channel,
and provide maximum benefit when flown in conjunction.
Example 1 – Thrust fault detection.
Example 3 – Fold mapping in the mountain belt.
back to Super- HRAM (Helicopter) Data
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