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 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 feasibility 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.