Unmanned aerial magnetic survey

Search for valuable mineral resources is always a complex task, which can be performed more easily using geophysical methods, specifically magnetic survey. Magnetic survey is usually the first step of any research on a newly discovered site.
Aeromagnetic survey can be applied for:
Locating ferrous and non-ferrous ores
Locating ferrous and non-ferrous metal ore;
Archeological objects
Archeological research;
Man-made metal objects
Locating man-made metal objects;
Rare metals
Search of rare and precious metals (Cu, Au etc.);
Diamond deposites
Exploration of primary and alluvial diamond deposites;
Geological mapping
Geological mapping of platform and rough terrain.
This kind of survey is possible because of ferromagnetic minerals presence in ores, which interferes with magnetic field in abnormal way.

Geophysical research methods are also used for geological applications as:

Geological mapping of platform and rough terrain;
Discovery of buried cultural artifacts.

Deposites survey

Recently aeromagnetic survey required helicopters or planes use to perform it in distant areas with rough terrain conditions. This was the main reason of extremely high price of such research.

Now, an affordable alternative became availible - aeromagnetic survey with unmanned quadcopter as a carrier. This method is perfect for severe terrains and especially useful in case there is a large altitude difference or swampy area. More importantly, it eliminates any risk for operator during the mission.

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Magnetic survey methods comparison

  Land survey UAV survey Aviation survey
Price
($/km)
from 105 from 32 from 24
Precision high / interference
exposure
high /
precise
average / complex
interference compensation
Performance
(km/day)
15 on average up to 220 up to 1000
Preparation complex simple complex / expensive
Human
error possibility
high none average/ crew life
risk

Unmanned magnetic survey efficiency

This method proved itself as a flexible tool for geophysics engineer. Key advantages:

Routes up to 220 km a dayFast battery change allows performing 12-16 flights in a row.
3D magnetic field mappingVisibility of results makes it much more efficient.
High survey detailingNo matter how rough terrain is, the results are accurate
Safe flight altitudeThe route is plotted above the 3D model to use the terrain curves to its advantage. It even takes trees and man-made objects into account to provide maximum safety level possible.
Excludes surface objects interferenceFlight smoothness reduces surface noise interference drastically.
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Comparison of magnetic survey data

Precise proximity flightDuring flight, magnetometric sensor keeps the same distance to the ground and moves with constant speed to make accurate counts every time.
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Detailed proximity flight results

Comparison of magnetic survey data

ММС-214 aviational magnetometer was used in 1988 to perform survey on the same site, where Geoscan 401 Geophysics system was applied in 2017. The results comparison is presented:

ABnormal magnetic field

Abnormal magnetic field (1988)Abnormal magnetic field 2017
year 1988
AN-2, ММС-214
Survey scale 1:25 000
year 2017
Geoscan 401 Geophysics
Survey scale 1:10 000

Magnetic field vertical gradient

Magnetic field vertical gradient 1988Magnetic field vertical gradient 2017
year 1988
AN-2, ММС-214
Survey scale 1:25 000
year 2017
Geoscan 401 Geophysics
Survey scale 1:10 000
Geoscan 401 geophysics

Geoscan 401 Geophysics for aeromagnetic survey

To use the advantages of unmanned magnetometric survey, Geoscan engineers developed compact and highly-accurate quantum magnetometer (Geoscan Shark QM-Rb1). Geoscan 401 industrial quadcopter acts as a carrier.

The system includes a ground control station with pre-installed “Geoscan Planner” flight planning software. With Geoscan Planner you can easily set up survey parameters, specify landing point, perform a preflight system check and launch the UAV. During the flight mission, GCS displays UAV status and position, that allows see aerial mission progress.

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GCS laptop

Application

In January, 2019, Geoscan specialists performed aeromagnetic survey in north-western part of Laos Republic on Aurora site. The results are presented as a abnormal magnetic field map and a set of profiles.

This model shows the site's geological structure and allows to observe highly magnetic linear zones, which, possibly, correspond with Mt+Cu+Au mineralization with large amounts of copper, iron ore and gold.

To acquire enough data on specified territory, it is necessary to explore it multiple times, placing magnetometric sensor on different altitudes. Most affordable and convenient way to do this is using UAV multi-level measurements method.

The results are most efficient to locate sub-surface geological structures, their form and three-dimensional positioning.

Aeromagnetic UAV survey results can be presented as volumetric model.

This model represents internal geological structure of the site and helps to visualize it properly.

It is also possible to set values range to distinguish different magnetic structures from one another.

In-depth modelling allows to evaluate reserves and calculate them with extreme accuracy.