Transcript Assegai Geophysics Overview

Airborne, Ground and Borehole Geophysics
For Civil, Geotechnical and Environmental
Contents
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INTRODUCTION
BENEFITS OF GEOPHYSICS
SOLUTIONS
CASE STUDIES
Engineering and Environmental
Geophysics
Exploration Geophysics
Mission
Improved site characterization by provision of accurate and cost-effective geophysical solutions using siteappropriate geophysical techniques
Vision
To become a preferred provider of geophysical solutions through innovative and sound application of geophysics
Geophysical Borehole Logging
Borehole Logging – Data processing – Log Analysis - Innovation
Gyrocopter Light Airborne Geophysics
Where Vision Becomes Reality!
Benefits of Geophysics
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Non-destructive and usually non-intrusive
Faster than invasive and destructive methods
Able to cover large areas and gives continuous data
Proven methods, based on physical parameters which links to geology
Cost-effective
Quantitative data
Use Geophysics to Investigate
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Shallow and deep voids in rock concrete or near subsurface materials
Fractures, joints bedding and faults: presence, positions and orientation
Resistivity profiling for grounding or cathodic protection requirements
Depth to bedrock
Concrete or tar road investigations
Lithological boundaries
Water leaks from retainers
Local stress (breakout)
Geology
Geological structure
P-wave and s-wave velocities that can aid in establishing engineering parameters such
as :
– Rippability of Earth materials
– Poisson’s ratio
– Shear, Bulk and/or Young’s moduli
Choosing Geophysical Methods
• Generally a direct trade off exists between resolution and spatial coverage
– For example, some downhole logs can measure cm scale anomalies but only in the
borehole while large and deep aquifers can be mapped with electromagnetic methods but
in very low resolution.
– Both will take a day or more to complete
• No physical property contrast, no geophysics
• Important to the success of any project to choose the correct tool for the
geological/geotechnical problem
RESOURCES AND PEOPLE
Alten du Plessis
(Senior Geophysicist
& Manager)
MSc Geophysics
(Wits)
Robert Whitehead
(Junior Geophysicist)
DP de Villiers
(Junior Geophysicist)
Equipment
MSc Physics
15 years experience
BSc Hons (Wits)
MSc Candidate
Software
Field Team
Contract Personnel
Open Ground Resources – List of Typical Services
• Engineering and Geotechnical
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Mapping of services & utilities
Mapping of voids (very shallow < 1m to deep up to 30m)
Dam Site Investigations to map bedrock depth, quarry sites, fault and fracture zones
Ground stability and gravimetric surveys
Ground earthing and corrositivity
Road pavement investigations (road layers, moistures, shallow voids)
Depth to bedrock and thickness of overburden / fill material
Stratigraphy and general geology
Compressional and shear wave velocity measurements (MASW, down-hole, cross-hole)
GPR in underground mining hanging wall investigations: Training and Support
• Environmental
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Landfill and groundwater contamination investigations
Mapping of preferential groundwater flow paths and permeable layers such as gravels, etc.
Mapping of buried objects
Mapping of pollution plumes
Case Study 1: Mapping of Buried Objects using Ground Penetrating Radar (GPR)
Open Ground Resources was requested by an industrial client to map the presence of buried metal drums containing hazardous material and to confirm the
presence and extent thereof. Magnetic and electromagnetic data were previously collected on the site but results were contaminated due to interference from
existing infrastructure.
Magnetic data displayed above could not be used to infer the
presence of the buried drums and interpretation was based on
the ‘known’ position of the buried objects.
GPR section with strong hyperbolic
anomalies interpreted as buried drums
The high resolution capability of the GPR technique was far superior to low resolution
magnetic and EM techniques and individual drums could be clearly observed. The
robustness of the technique with respect to interference from infrastructure makes it
ideal for application in industrial environments where maximum detail is required.
Case Study 2: MASW and Surface Waves to Map Fracture Zone in Open Pit Side Wall
The dispersion of Surface Waves can be used to provide a rapid means of
producing a continuous shear wave velocity section of the shallow subsurface,
up to depths of 20-30 metres can be mapped using a large sledgehammer.
The MASW method (Multi Channel Analysis of Surface Waves) was used to
map the presence of induced fractures in the sidewalls of a large open-pit.
These fractures are pre-dominantly vertically orientated and present a difficult
target for conventional geophysical methods as very high resolution are
required to map the fracture zones. A series of parallel MASW sections were
acquired using a land-streamer system (as shown in Figure to the right).
The land-streamer allows for semi-continuous acquisition of MASW data, the
streamer is moved at 1-2 m intervals with sledgehammer impacts shots at the
one end of the spread.
The MASW results showed a very consistent zone of low shear wave velocity on
all three MASW sections next to the open pit, with the reduction in shear wave
velocities interpreted from the presence of known fractures. An example of
data is shown to the left, with the position of the low-velocity zone indicated.
The results could be used to infer the spatial extent of the fracture zones .
Advantages of the MASW method
Shear wave velocity section with zone of low bedrock
velocity at the start of the section clearly visible
* No boreholes or difficult shear wave refraction survey are
required to produce a shear wave velocity section
* Does not suffer from velocity inversions as is the case with seismic
refraction
*Can be used in industrial areas and on tar/concrete surfaces
Case Study 3: Electrical Resistivity Imaging (ERI) for Lithology and Quarry Investigations
at Dam Site
Site A: Very resistive shallow and unweathered dolerite confirmed by drilling,
suitable for dam construction material. Drilling confirmed thickness of 30 metres.
Electrical Resistivity Imaging has been used for a dam site in Kwazula Natal, to source the depth and
lateral extent of dolerite for dam construction purposes. Potential quarry sites were selected based on
the visual appearance of dolerite outcrop and ERI was then used to map the depth and lateral extent of
dolerite lithology. A total of four quarry sites was investigated, and three sites could be immediately
discarded based on the ERI results with a resulting saving in drilling costs and investigation time.
Site B: Thin & weathered dolerite on surface underlain by more conductive mudstones; this site was found
unsuitable for dam building material.
Case Study 4: Application of Seismic Refraction at Coega Harbour, Port Elizabeth to
Map Faulted Quartzite
Application of the Seismic Refraction method proved to be a fast and effective means
of mapping a block of faulted shallow quartzite encountered during a routine drilling
investigation as part of the Coega Project, Port of Nqguru. Initial drilling had to be
halted due to logistical and safety issues with the unknown extent of possible shallow
bedrock of immediate concern in terms of excavation and harbour construction.
Jon McStay, WSP: “The design options for the terminal,
dredge basin and associated infrastructure was thus largely
based on the seismic refraction data”.
The seismic investigation provided accurate delineation of the shallow bedrock by
integration of the seismic results with available borehole information with a quick
turnaround time, without any mayor project delays.
Data was processed using SeisOpt2D and bedrock velocity
ranges was contoured to image bedrock datum elevation as
shown to the left.
Case Study 5: Electrical Resistivity Tomography to Map Concrete Integrity for Tower
Foundation
Electrical Resistivity Tomography (ERT) was used to evaluate the integrity of soil-crete foundations columns
which was found to be inconsistent in depth and diameter when investigated after column construction. It
was found that the columns were thinner in places than the design parameters, and concrete was also entirely
missing at certain depths.
The Supersting R8 8-channel Resistivity system was used to acquire ERT
data between 3 boreholes using two cables with 28 electrodes each @ 0.5
m spacing. The powerful 8 channel capability of the Supersting allowed for
the collection of more than 5000 measurements in approximately 4 hours,
allowing for high measurement density and stable inversion results.
Footprint of Tower Foundation with soil-crete colomns. Boreholes used for
tomography survey indicated in red.
Wireline Logging
Precision, objectivity and
continuity are the key
attributes of geotechnical
wireline data.
Downhole methods
Wireline Worksop specialises in developing custom solutions to our clients problems
Current capabilities include:
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Optical and acoustic televiewer
Resistivity
Sonic transit time
Natural gamma
Density
Temperature
Three-arm caliper
Porosity and permeability
Optical televiewer
Optical televiewers work best in clean
dry holes but will work perfectly well in
clean water – sometimes it’s worth
cleaning out a borehole before logging it.
Advantages
• Virtual core
• Continuous
• In-situ
• Orientated
What can we gain from this data?
• Bedding, joints, fractures, voids
• Lithology
Optical televiewer
Sonic log
Tight layer
Density log
Describes lithology
Full Waveform Sonic log
With P and S waves, we
can calculate the dynamic
moduli of elasticity
Semblance
Need to measure the P-wave
first arrival time and the Swave transit time
Acoustic televiewer
Juxtaposition with density
Acoustic televiewer - DIFs
Drilling induced events must be recognised and purged from derived logs.
Acoustic televiewer - Breakout
Acoustic televiewer – Stress rotation
In this example the stress orientation,
indicated by breakout, has rotated by 55
degrees.
A nearby fault is indicated.
Acoustic televiewer – picking Images
Manual picking involves placing a projected curve over a
fracture plane and classifying the type of event picked.
Automatic picking is available. It is quicker but lacks detail
and certainty.
Basic structure classification might include:
• Sedimentary bedding
• Veins
• Lithological boundaries
• Fractures
• Faults
Acoustic televiewer – fault drag and block rotation
Structure logs – presentation
Wireline logs offer
• Continuous measurement (no gaps)
• Objectivity (not an opinion)
• Precision (repeatable and vertically proportional / one event)
• In situ measurement
• Accuracy (via calibration or empirical conversion)
• High resolution of televiewer images
• Orientation of fractures and bedding
• Aperture of open fractures
• Orientation of maximum horizontal stress tensor
• A permanent digital record (easy manipulation and transmission)
Limitations of wireline logging
• Some logs cannot be captured in dry holes (sonic data)
• Density has relatively poor resolution
• Sonic logs are not necessarily measuring IRS
• Shear waves cannot be measured in slow formations
• Empirical data are needed for UCS and elastic moduli conversion
• Optical televiewer is superb…but needs a clean hole and/or clean water
• Proper planning to circumvent these limitations is necessary
List of Services
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Training in data capture (field operations)
Training in logging theory and radiation safety
Advising on logging modus operandi / planning field operations
QA of logs and logging contractor's procedures (in the field)
Intervention services (problem solving during operations)
Data processing and presentation to best effect
Log analysis and derivation of relevant outputs
Formal project reporting with conclusions and recommendations
Presentation of results
Gyrocopter Light Airborne Geophysics
Where Vision Becomes Reality!
Presented by
Dr. Laurent AMEGLIO
(GyroLAG – CEO & Technical Director)
Disclaimer & Forward-looking Statements
This document/presentation (the “Document”) has been prepared by GyroLAG (the “Company”) solely for information purposes only and shall not be regarded neither as
a proposal, acceptance, nor as a statement of will or official statement from Company and/or subsidiaries and/or affiliates and/or associates. This Document is the sole
responsibility of the Company. Information contained herein does not purport to be complete and is subject to certain qualifications and assumptions and should not be
relied upon for the purposes of making an investment in the securities or entering into any transaction. The information and opinions contained in the Document are
provided as at the date of the Document and are subject to change without notice and, in furnishing the Document, the Company does not undertake or agree to any
obligation to provide recipients with access to any additional information or to update or correct the Document.
In preparation of this Document, Company has exercised reasonable skill, care and diligence. The statements, conclusions and recommendations contained herein might
be based upon data obtained from third parties. No warranty or undertaking is made in respect of information that was obtained and used in this Document and which,
unknown to Company, was incorrect or incomplete.
Neither Company, nor any of its employees, nor any of their contractors, subcontractors or their employees, nor any of its Associates and shareholders, makes any
warranty, express or implied, or assumes any legal liability or responsibility whatsoever for, or in respect of, any use of, or reliance upon, this Document by recipient or
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state or reflect those of Company.
This document may contain "forward-looking statements and information” that are based on the Company's current expectations, estimates and projections about future
events and financial trends affecting the Company. Forward-looking statements and information can be identified by the use of words such as "may," "will," "should,"
"expect," "estimate" or other comparable terminology. Forward-looking statements and information are inherently subject to risks, uncertainties and assumptions, many
of which the Company cannot predict with accuracy and some of which the Company might not even anticipate. Important factors, which may affect these expectations,
estimates and projections and may cause expectations, estimates and projections to differ materially from those expressed in the forward looking statements and
information contained herein, include, but are not limited to: (i) continued availability of capital and financing; (ii) Company's ability to borrow on favourable terms; (iii)
general economic, market, business or governmental conditions; (iv) adverse changes in the airborne geophysics markets including, among other things, increased
competition with other companies, market prices; (v) risk of airborne surveys acquisition and development, including, among other things, risks that projects may not be
completed on schedule, that Clients may not or delay payment for services rendered by the Company to them, or that development or operating costs may be greater
than anticipated; (vi) risks of investing through joint venture structures, including risks that the Company's joint venture partners may not fulfil their financial obligations
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that these expectations, estimates and projections will be achieved. Future events and actual results may differ materially from those discussed in the forward-looking
statements.
GyroLAG – Company profile
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Technologies
Industries
Magnetic
Gamma spectrometry
Digital video
Aerial photo
Thermal imaging
Laser scanning
Scalar gravity
Multi- and Hyper-spectral
Self-Potential (Experimental)
Electromagnetic (R&D)
Mining
Security
Environment
Civil Engineering
Water Exploration
Mineral Exploration
Geological Mapping
Precision Agriculture
Oil & Gas Exploration
Where Vision becomes Reality !
www.gyrolag.com
[email protected]
GyroLAG – About the company
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GyroLAG (Pty) Ltd (Gyrocopter Light Airborne Geophysics), headquartered at Potchefstroom airport (South Africa,
26°40"05' S / 027°05"05' E WGS84), brings to reality the next generation of advanced and innovative airborne multisensor geophysical platforms to the natural resource exploration, environmental, civil engineering and precision
agriculture industries.
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Established in 2011 in Johannesburg, the vision of GyroLAG was to develop a small and stable multi-sensor
platform, resulting in highly flexible surveys flown at low/reasonable cost of operation.
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GyroLAG is 'Where Vision Becomes Reality'!
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GyroLAG owns complete airborne geophysical systems which are installed on board customized gyrocopters (our
flagship aviation platforms - see technical profile below) and one light fixed-wing aircraft, suited for a wide range of
topographic and environmental conditions.
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By using latest technological developments and out of the box thinking in both airborne carriers and geophysical and
geomatics sensors, GyroLAG is available to carry out specialized airborne surveys to individuals, consultants,
exploration companies, government entities, farming and environmental groups.
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Customizing its aircraft, GyroLAG also provides an uncompromising commitment and culture to
'Safety by Design, Not by Default'!
GyroLAG – Company profile
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GyroLAG – Tool box
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GyroLAG's selection of technology for geophysical and remote sensing applications are presented on the right with:
two three-components fluxgate magnetometers (a to d); gamma-ray spectrometers (4 ltr CsI and 16 ltr Nal with full
spectrum analysis – e); scalar gravimetry (1 mGal accuracy for 2 km full wavelength resolution – f); a CCD digital
video/aerial photos system (g); a thermal imaging camera (h); a laser scanner - LiDAR (i); DTM (j); data
interpretation products e.g. physical geology (k) and structural map (l).
GyroLAG – Company profile
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GyroLAG – Industries and applications
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By using latest technological developments and 'in new box' thinking in both airborne carriers and geophysical and
geomatics sensors, GyroLAG is available to carry out specialized airborne surveys to individuals, consultants,
exploration companies, government entities, farming and environmental groups along three main applications:
ROC - Resources Observation Carrier
... Light aircraft airborne geophysics and geomatics for the natural
resources exploration (mineral, water, oil and gas, etc).
(The Roc is a legendary bird of prey from Eastern mythology)
LEAF - Light Environmental & Agricultural Flying
... Light aircraft airborne geophysics and geomatics for the precision
farming and environmental industries.
(The ginkgo leaf is a living fossil dating back 270 million years)
ACE - Airborne Civil Engineering
... Light aircraft airborne geophysics and geomatics for the civil engineering
industries for roads building to mine infrastructures.
GyroLAG – Company profile
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GyroLAG – Products
TMI
DTM
NIR
K
Th
Tilt
U
Ternary
TIR
TotC
Photo
GyroLAG – Company profile
LiDAR
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GyroLAG – Interpretation products
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GyroLAG is also an exciting infusion of cutting edge science and expert interpretation that transform data into
knowledge:
Sub-outcrop geology map extrapolated from geophysical data and
2D models for PGE exploration.
Airborne total magnetic field map with selected targets (e.g. for
REE exploration).
Magnetite (green) and pyroxenite (beige) parts of a carbonatite
complex in Africa.
GyroLAG – Company profile
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GyroLAG – Technologies
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Devoted to the development of innovative and cutting edge airborne technologies and solutions, GyroLAG brings the
following bouquet of unique technological and geo-scientific applications to the industry:
FLAME – FLuxgate Airborne MagnEtic
... an association with Unistra (France)
POFADER – POtential Field Airborne DEtection & Record
SWIFT - Short Wave InFrared Technology
... A unique near- or short-wave infrared spectral profiler for
geological and mineral mapping. Under development.
GyroLAG – Company profile
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GyroLAG – Research and development
GyroLAG has also established strong ties and partnerships with academic and scientific entities at:
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UNISTRA - University of Strasbourg (France)
... development in airborne fluxgate magnetic surveying.
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NMMU & AEON - Nelson Mandela Metropolitan University (South Africa)
... AGEO - Airborne GEophysics Observatory.
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TUT - Tshwane University of Technology (South Africa)
... contributing to the airborne geophysics component of TUT's Science &
Technology Train project.
GyroLAG – Company profile
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GyroLAG – Research and development
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NWU - North West University (South Africa)
... development on airborne geophysics for precision agriculture and environmental
applications. Under discussion.
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Hochschule Koblenz & Fraunhofer - University & Research Institute (Germany)
... development NIR and TIR airborne mapping.
GyroLAG – Company profile
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GyroLAG – Trading innovations
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GyroLAG also invite you to join its ... FEEL - Frequent Executive Explorer League ... the world first and unique
frequent airborne geophysics flyer program.
With FEEL you earn valuable miles when you fly airborne geophysics or remote sensing
with GyroLAG. You can redeem your miles for new airborne geophysical surveys with
GyroLAG, special interpretation products, and much more.
Depending on the number of miles you earn within a period, you can also achieve status
and enjoy many special and exclusive geophysical privileges for your exploration and
mining activities.
GyroLAG – Company profile
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GyroLAG – Trading innovations
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GyroLAG is also a founding member of Assegai
Geophysics
(www.assegaigeophysics.com),
a
consortium of geophysical consulting and contracting
companies led by a team of industry experts with more
than 100 years of combined experience worldwide and
with a strong Africa focus.
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Assegai Geophysics is the portal of choice for integrated
tailored geophysical solutions in airborne, ground,
marine, wireline and data modelling applications to the
natural resources exploration, environmental, civil
engineering and precision agriculture industries.
GyroLAG – Company profile
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GyroLAG – Trading innovations
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GyroLAG is also now offering its gyrocopter airborne geophysics platform as a franchise with two configurations:
FLAG platform (Fly Light Airborne Geophysics)
FLAReS platform (Fly Light Airborne Remote Sensing platform)
GyroLAG – Company profile
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GyroLAG – Applied Research Centers
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GyroLAG teamed up with AEON, the Earth Stewardship Science Research Institute at the NMMU (South Africa),
setting up AGEO to provide light airborne geophysics support to earth systems science research projects, linking
marine to continental environments.
GyroLAG – Company profile
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GyroLAG – Applied Research Centers
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GyroLAG is looking for an academic entity interested to contribute to its 'X-farm' program to provide the agriculture
industry with a state-of-the-art affordable light airborne remote sensing (inc. geophysics) support for crops and farm
management.
GyroLAG – Company profile
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GyroLAG – Aviation
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GyroLAG fleet is made of unique and versatile light airborne platforms that provide a blend of capabilities to perform
effectively in any surveying environment.
GyroLAG – Company profile
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GyroLAG universe
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GyroLAG and its partners have created a compelling momentum at the cutting edge of airborne geophysics. We
interface a research & innovation hub and a commercial hub pulling together unprecedented forces to provide the
industry with unique and tailored solutions and services.
GyroLAG – Company profile
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GyroLAG – Offices
GyroLAG South Africa
ATC Tower, Potchefstroom Airfield (South Africa)
(WGS 84) 26°40"05' S / 027°05"05' E
Mail: P.O. Box 21153, Noordbrug 2522, South Africa
E-mail: [email protected]
Web: www.gyrolag.com
Reg. no.: 2011/129433/07
GyroLAG Botswana
Unit 7, plot 101, Commerce Park, Gaborone,
Botswana
Mail: P.O. Box 95ADD, Postnet Kgale View,
Gaborone, Botswana
E-mail: [email protected]
Web: www.gyrolag.com
Reg. no.: CO2013/12910
GyroLAG Australia
179 Back Yamma Rd, Parkes, 2870, NSW,
Australia
Mail: 179 Back Yamma Rd, Parkes, 2870, NSW,
Australia
E-mail: [email protected]
Web: www.gyrolag.com
GyroLAG – Company profile
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GyroLAG – Around the world
GyroLAG – Company profile
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Gyrocopter Light Airborne Geophysics
Cell.: +27 84 787 1000
Email: [email protected]
Web: www.gyrolag.com
Where Vision becomes Reality!