The survey division of Micro-g LaCoste & Scintrex
MGL Surveys specializes in providing high accuracy surface and
downhole gravity surveys. We utilize the following
instruments, all of which are manufactured in-house:
This unique instrument capability allows MGL surveys to provide the most efficient and accurate micro-gravity surveys available.
- Micro-g LaCoste A10-X and FG5-X absolute gravity meters.
- Scintrex CG-5 relative gravity meters.
- Bluecap and Gravilog borehole gravity meters.
Absolute Gravity Surveys
and Data Processing
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Micro-g LaCoste now offers a complete suite of absolute
gravity survey services, including both observation and data
processing, to the geophysical, explorations, and metrological
communities. Applications include primary control for
relative gravity networks, long term vertical deformation and
subsidence monitoring, monitoring of underground fluid
movement, and calibration of inertial navigation and force
For maximum efficiency in obtaining large networks of
micro-gravity networks, MGL Surveys is proud to offer our Hybrid Gravity®
System. This combination of an A10-X and a CG-5 eliminates the
need for off area base ties and minimizes time consuming
- Micro-g provides absolute
gravity survey services at outdoor and indoor environments
- Past survey projects include vertical uplift monitoring
in the New Zealand Alps and water flood injection mapping in
the harsh arctic environment of the Prudhoe Bay oil field.
Micro-g has also provided 2 µGal accuracy calibration
reference points for high precision metrology and
calibration laboratories located throughout the world.
- Our experienced field scientists and engineers, together
with our absolute gravity instrumentation, ensure absolute
gravity data products are of the highest quality.
- Micro-g's proven g absolute
gravity data acquisition and processing software uses
advanced data processing techniques. The software ensures
that geophysical, environmental, and metrological
corrections are applied according to strict standards agreed
upon by the scientific community. Independent
(re)processing services of absolute gravity data are also
MGL Surveys Borehole
Gravity Survey Services
MGL Surveys, provides
logging services with two borehole gravity instruments. The
Gravilog tool is designed to operate in the slim holes of the
mining industry. The Bluecap tool is designed for the petroleum
industry with higher temperature and pressure ratings.
Borehole gravity tools measure relative gravity within a
borehole to the same accuracy levels as surface gravity meters. These
measurements are used for remote sensing and deep investigation
density logs without the need for radioactive sources.
Typical survey objectives of Bluecap℠ borehole gravity surveys are:
- Time lapse monitoring of gas/oil and gas/water reservoirs and CO2 sequestration.
- Large volume density through casing
- Overburden pressure measurement offshore and for gas storage in salt
- Mapping remote structure eg. salt flanks.
- Carbonate porosity measurement
The Gravilog tool is designed for shallower mining
and geotechnical studies. Typical Gravilog℠ survey
- Large volume bulk density measurements in homogeneous, heterogeneous and heavily fractured rock units.
- Remote sensing of massive sulphide deposits and 3D inversion with multiple wells and surface gravity.
- Identification of nearby conductors as graphitic or metallic.
- Ore grade delineation with multiple wells and surface gravity.
- Overburden density determination.
- Void detection.
Combination Borehole and Surface Micro-Gravity Surveys
A combination of borehole and surface micro-gravity surveys is
well suited for for time lapse reservoir monitoring tasks,
particularly when oil / gas or gas / water fluids are
CO2 sequestration monitoring is another use for the surface /
Feasibility Studies and Survey Interpretation
MGL Surveys performs pre-survey fewsibility studies using
state of the art forward modeling and inversion techniques for
surface and borehole surveys.
MGL can take reservoir or seismic gridded data to generate
forward response models, add noise and invert the resulting
noisy data to provide realistic forecasts of interpreted
survey responses. This guides the decision to perform a survey
and determines the most effective measurement locations and
The same inversion techniques used for the feasibility studies
can be applied to data interpretation with suitable
constraints imposed by, for example, reservoir geometry and 4D
Current Instruments Available for Field Work
FG5 instrument in metrology laboratory.
- Absolute Accuracy: ± 2 µGal1
- Measurement Precision: ± 1 µGal
- Integration Time to 1 µGal: 1 hour
- Operation: Indoor and Outdoor (Protected Environments)
A10 instrument during winter field survey.
- Absolute Accuracy: ± 10 µGal2
- Measurement Precision: ± 5 µGal
- Integration Time to 10 uGal: 5 minutes
- Operation: Indoor and Outdoor (Exposed Environments)
- Acquisition: 30 minutes minimum including setup, occupation, and tear down time
Bluecap Borehole Gravity Tool
- Sensor: Metal, Zero-length spring
- Outside diameter: 60 mm (2-3/8").
- Maximum temperature: 160C
- Maximum pressure: 15,000 PSI
- Maximum deviation: 93 degrees from vertical
- Wireline cable: Single, 4, or 7 conductors
- Reading resolution: 1 uGal
- Standard deviation: 7 uGal
The Gravilog Borehole Gravity Tool
- Sensor: Fused quartz
- Outside diameter: 50 mm. to fit in NQ drill rod.
- Maximum temperature: 80C
- Maximum pressure: 3500 PSI, equivalent to 2400m
- Maximum deviation: 60 degrees from vertical
- Wireline cable: 4 conductor, GO cablehead
- Reading resolution: 1 uGal
- Standard deviation: 7 uGal
Previous Absolute Survey Customers4
- British Petroleum Exploration, Alaska
- U.S. Army Metrology Division
- National Science Foundation
- Scripps Institution of Oceanography
- Columbia University
- National Imagery and Mapping Agency
- U.S. Naval Surface Warfare Center
- U.S. Geological Survey
Contact Micro-g for more information on any of these services.
1Based on observations taken at
the NOAA Table Mountain Gravity Observatory.
2As determined by comparison with
3Gravity gradient determination
also available with A10 surveys.
4Included are both direct and
indirect contacts. Refrence contacts and example reports are
available upon request.