MGL Surveys

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:
  • Micro-g LaCoste A10-X and FG5-X absolute gravity meters.
  • Scintrex CG-5 relative gravity meters.
  • Bluecap and Gravilog borehole gravity meters.
This unique instrument capability allows MGL surveys to provide the most efficient and accurate micro-gravity surveys available.

Survey Services Icon Absolute Gravity Surveys and Data Processing

Click here to download a printer-friendly description of our absolute survey services (PDF® format).

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 measurement systems.

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 looping.

  • Micro-g provides absolute gravity survey services at outdoor and indoor environments world wide.
  • 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 available.

MGL Surveys Borehole Gravity Survey ServicesBluecap logo

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 objectives are:

  • 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 involved.
CO2 sequestration monitoring is another use for the surface / borehole combination.

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 timing.

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 seismic.

Current Instruments Available for Field Work

  • FG5-X Absolute Gravimeter

    FG5 gravity meter metrology survey

    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 Absolute Gravimeter

    A10 gravity meter winter survey

    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 logoBluecap™ 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
  • JILA
  • National Imagery and Mapping Agency
  • U.S. Naval Surface Warfare Center
  • U.S. Geological Survey
  • N.O.A.A
  • C.I.R.E.S

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 an FG5.
3Gravity gradient determination also available with A10 surveys.
4Included are both direct and indirect contacts. Refrence contacts and example reports are available upon request.