How is the Gedex HD-AGG different from other gravity gradiometers, and why are these differences so
important?
The Gedex HD-AGG is designed to outperform current systems by an order of magnitude, allowing it to
“see” important signatures that would otherwise be missed: Signatures that can help lead to
multi-billion dollar discoveries of natural resources.
The Gedex HD-AGG combines an instrument, designed for exploration in an aircraft, which accurately
measures the gravity gradient at a very fast rate, and an isolation system to further enhance its
performance. The HD-AGG is built on proprietary technologies developed by Gedex, in combination with
technologies licensed from the University of Maryland and Rio Tinto. These key technology differences
result in a dramatic improvement in noise levels to 1 Eotvos per √Hz.
The important result: Clear images of resource signatures.
The competitive edge delivered by Gedex is clearly evident in this channel sand example, imaged here
from one data set that represents the performance of conventional technology, and another data set
reflecting Gedex’s improved technology.
Systems using conventional technology are limited, and the image on the left shows how important
geological features are lost in the noise. In contrast, the image on the right shows the superior
performance of the Gedex HD-AGG, enabling identification of critical features.
Identifying channel sands – pockets of ‘clean’ sand that are free of shale – is important in the
development of Canada’s oil sands. Efficiently locating channel sands reduces unnecessary drilling,
saving time, lowering costs, and reducing the environmental impact of oilsands development. The the
Gedex HD-AGG provides similar advantages in many other areas of geophysical exploration.
INDUSTRY CHALLENGES & OPPORTUNITY
There is a pressing need in exploration for new technology that:
- Increases the certainty of discovery
- Identifies new resource opportunities
- Improves the time to market
- Lowers overall exploration costs
Easy discoveries have been made. The IEA (International Energy Agency) estimates the world will need to
spend over $1 trillion per year to bring on new supplies of oil. Much of this will be directed towards
deeper and more challenging and complex geology, where new technology such as the Gedex HD-AGG can
greatly assist imaging. Although airborne gravity gradiometry has been used since the mid 1980s,
existing systems appear to have reached their technological limits and still do not provide a defining
signal.
All current commercial gravity gradiometer systems are derived from Lockheed Martin technology. This
technology was initially designed for use in a submarine, and not designed to achieve the resolution
needed for resource exploration. The Gedex HD-AGG was designed from first principles to achieve
performance beyond systems deployed today – performance that can enable discovery.
Major corporations that modeled the gravitational signatures of important targets of interest defined
this performance to be:
•High Sensitivity
Gravity gradient error variance less than 1 Eotvos per √Hz; and
•High Spatial Resolution
Data acquisition sampling at the 1 Eotvos per √Hz noise level every second (approximately 60 metres
spatial resolution for data collected from an aircraft); and
•Operability Under Typical Survey Conditions
High accuracy and high spatial resolution maintained even in moderate turbulent conditions.
The impact on exploration can be seen in some two-dimensional examples below. Gedex technology also has
a dramatic impact on 3D inversion and provides the capability to improve seismic imaging through better
velocity models more accurately imaging salt bodies. Please contact us for further information
applicable to your exploration requirements.
DIAMOND EXPLORATION – IDENTIFYING KIMBERLITES
The largest diamond mines possess low density, non-magnetic caps making gravity one of the best tools
for new discoveries. Existing airborne gravity gradiometer systems will not reliably detect economic
deposits and the Gedex HD-AGG will have the noise and resolution specifications to be successful in this
space.
This model shows two relatively small kimberlite bodies, typical of those found in Canada.
The current fixed wing system (7E / √Hz) and the more expensive helicopter borne system (3E / √Hz )
modeled below show that the kimberlites would be essentially invisible due to system noise:
The modeled data from the Gedex HD-AGG is shown below. The much lower background noise provides a
dramatic improvement over the current state of the art systems, which would clearly allow the accurate
identification of the drill targets. False targets due to noise are virtually eliminated which will
decrease exploration cost and environmental damage from negative drilling results.
MINERAL EXPLORATION – IDENTIFYING A COPPER PORPHYRY DEPOSIT
A model of a copper porphyry deposit is shown below (Spence deposit in Chile, model supplied to CAMIRO
by BHP-Billiton). With conventional technology the deposit is lost in the noise, but once again the
improved resolution of the Gedex HD-AGG would enable the discovery.
Best Available System Today
Ambiguous Image
Gedex HD-AGG
Copper Deposit Detected