Geophysical borehole surveys play an essential role in environmental, geotechnical and mineral exploration studies.
Geophysics GPR has been performing borehole logging for over two decades.
Borehole logging typical tools and applications include:
Borehole Radar: Investigates a cylinder shaped volume around the borehole with a radius of 10 - 100 m; applications include fracture and fault characterization, karst imaging, detection of voids, thickness of aquifers and delineation of salt-water intrusion;
Caliper: The three arm caliper probe provides a single continuous log of borehole diameter as recorded by three mechanically coupled arms in contact with the borehole wall; Applications include location of borehole collapse or obstructions, cement volume calculations for grouting, identification of hard and soft lithologies, location of cracks, fissures, caving, faulting, casing breaks, correction of other logs affected by borehole diameter;
EM39 Induction Log: Provides measurement of the electrical conductivity of the soil and rock surrounding the borehole; applications include groundwater contamination monitoring, groundwater localisation, mineral exploration, and general geotechnical investigations;
Full Waveform Sonic: The tool emits a series of high frequency sonic impulses. Following their passage through the borehole fluid and formations, receivers at various distances from the transmitter detect these impulses. At each receiver, the arriving waveform is digitally sampled. Applications include cement bond logs (CBL), measurement of permeability index, estimation of elastic moduli of rock and as a specialist tool to carry out deep fracture identification;
Gamma Ray: Measures the natural-gamma radiation released from potassium and the decay products of uranium and thorium in the borehole; Applications include indication of clay or shale content, discriminating lithologies, identifying uranium ore body concentration and thickness and strata correlation between wells;
Normal Resistivity: Measures the apparent formation resistivity; application includes water quality, lithological and structural changes;
Optical Televiewers: Provides continuous high-resolution oriented optical image of the borehole wall and will work with or without presence of fluid in the borehole; applications include structural studies, fracture detection and evaluation, detection of thin beds, determination of bedding dip and lithological interpretation;
Acoustic Televiewers: Provides continuous high-resolution oriented ultrasonic image of the borehole wall and will work even with opaque borehole fluid; Applications include structural studies, fracture detection and evaluation, detection of thin beds, determination of bedding dip, breakout analysis, monitoring of earth stress field, casing inspection and high resolution calliper.
For more information, please contact our Ground Survey Team.
Geophysics GPR offers the full range of borehole imaging and geophysical logging tools. With the latest generation of acoustical and optical televiewer probes and acquisition equipment, we can provide high-resolution images and allow precise structural assessment for geotechnical studies.
We also offer versatile solutions for conducting cone penetration tests (CPTu) to measure tip resistance, dynamic pore pressure, and sleeve friction continuously during penetration.
Our borehole geophysics and R&D teams are currently building an all-in-one borehole geophysics mobile laboratory which will allow us to carry out multi-parameter surveys from a single acquisition vehicle.
The following are the most common techniques in borehole geophysics:
- Optical telewiewer and natural gamma
- Acoustic televiewer
- Conventional parameters (resistivity, mag. susceptibility,full-waveform sonic, caliper, etc.)