Tech-Log™
Tech-Log™ characterises the rock mass in and beyond the borehole wall. Oriented acoustic and optical televiewer images, caliper, full-waveform sonic and borehole radar for slopes, excavations, shafts, tunnels and foundations.
What Tech-Log™ answers
Tech-Log™ is geotechnical and structural characterisation by wireline logging: fully oriented, high-resolution images of the borehole wall and radar imaging of the ground beyond it, giving fracture, fault and bedding orientations, RQD and aperture, borehole condition, sonic velocities, dynamic elastic properties and off-hole reflectors.
Key answers
- StructureFault, shear, fracture, bedding and foliation orientations, classified
- RQD & apertureFracture frequency, RQD and aperture from oriented images, without oriented core
- Borehole conditionDiameter, ovality, washouts and breakouts from the caliper
- Sonic velocitiesP and S wave velocities from full-waveform sonic
- Elastic propertiesContinuous dynamic elastic moduli from density and sonic
- Off-hole reflectorsStructure imaged tens of metres from the hole with borehole radar
- StressBorehole breakout analysis and multi-hole field stress models
Applications
- Open-pit slope design
- Underground excavations and ground support
- Shafts and raise bores
- Tunnels
- Dam foundations
- Roads, bridges and major foundations
Tools in the Tech-Log string
- Acoustic televiewerUltrasonic image of the wall in any fluid: open fractures, breakouts and hole shape, oriented to north
- Optical televiewerTrue-colour photograph of the wall in clear water or air: lithology, veins and healed structure
- CaliperHole diameter, ovality and breakout orientation; the first log we look at
- Full-waveform sonicP and S velocities for dynamic moduli and rock-mass classification
- Borehole radarHelix Geotech memory-based radar imaging structure tens of metres into the formation
- Hazardous holesUnderground deployment system for holes crews cannot safely approach
Our Helix Geotech fully memory-based borehole radar system images structure tens of metres into the formation from a single hole.
Applications: blast holes for process optimisation and ground support · cover holes to detect water or methane-bearing fissures · geological holes to image mineralised reefs · pilot holes for shaft and raise-bore operations · development planning and 3D block modelling · tunnelling for fracture, void and metal object detection.
Understanding subsurface structures and formation mechanical properties is vitally important to any excavation or construction project. Tech-Log delivers the oriented evidence those designs depend on.
Tech-Log™ questions
What is the resolution of a televiewer image?
Acoustic televiewers typically sample 1 to 2 mm vertically at 144 to 288 samples around the hole; optical televiewers are similar or finer. Millimetre-scale fractures and bedding are routinely resolved.
What features in the borehole wall can the televiewers map?
Open and healed fractures, faults, veins, bedding, foliation, contacts, vugs, breakouts, casing damage and, on optical images, colour, texture and mineralogy. Every feature is oriented with dip and dip direction.
What is the difference between an acoustic and an optical televiewer?
The acoustic televiewer (ATV) images the wall with an ultrasonic pulse, recording travel time and amplitude, and works in muddy or opaque fluid. The optical televiewer (OTV) records a true-colour photograph of the wall and needs clear water or air. ATV emphasises open fractures and hole shape; OTV shows lithology and healed structure.
How do televiewers orient the image?
Each tool carries a three-axis magnetometer and accelerometers, so every scan line is referenced to magnetic north and to the high side of the hole. In magnetic ground or steel casing a gyro reference is used instead.
What in-hole conditions affect televiewer data quality?
Rough or washed-out walls, hole ovality, thick mud or gas bubbles (ATV), turbid fluid (OTV), rapid tool rotation and off-centre tool position. A caliper log and centralisers address most of these.
Why is a caliper log so important?
The caliper measures hole diameter. It corrects the other logs for hole size, shows washouts and breakouts that affect data quality, identifies fractured zones, and reveals in-situ stress direction through breakout orientation.
Can Tech-Log replace oriented core?
For structural orientation, yes. Televiewer images give true dip and dip direction of every feature, including zones of lost core, and restore orientation where core orientation failed. Core is still needed for strength testing and mineralogy, which the logs then extend along the whole hole.
More in the FAQ & glossary.
Field results
Kariba Dam rehabilitation
Rock mass characterisation of the plunge pool with advanced imaging.
Open the studyTech-LogCase studyRadar off-hole imaging of a platinum reef
Mapping reef geometry away from a single borehole.
Open the studyTech-LogCase studyIn-situ stress from borehole breakout
ATV breakout analysis and multi-hole field stress models.
Open the studyTech-LogCase studyUnderground deployment in hazardous holes
Fully oriented images from holes crews cannot approach.
Open the studyTech-LogCase studyOrienting radar reflectors with televiewer images
2D radargrams meet oriented borehole images.
Open the studyTech-LogCase study3D off-hole imaging from a three-hole fan
Joint 3D radar interpretation of unintersected structure.
Open the study