Very Broadband Borehole Systems
Applications
- Vertical seismic profiling
- Microseismic monitoring
- Robust velocity subsurface modelling
- Teleseismic earthquake monitoring
- Nuclear test ban treaty monitoring
Very Broadband Borehole Systems
Borehole installations offer excellent performance for low-noise detection of weak seismic signals such as from local microseismic events or from regional/teleseismic earthquakes.
We recommend you read our Very Broadband Borehole Systems brochure as we offer a range of options to assist you in achieving measurement at depth, allowing you to get closer to the seismic event and improve the accuracy of sub-surface velocities and event depths.
Our ‘very broadband’ borehole (VBB) system can house a weak-motion seismometer, a strong motion accelerometer, or a combination of the two.
If the borehole deviates from the vertical path we recommend our Radian system which can be installed at any angle.
The 5TB houses an accelerometer that is designed for strong-motion borehole studies. in cased holes with diameters of 99 to 203 mm
The 5T Borehole (5TB) accelerometer is designed for capturing strong motion and high intensity shaking.
- Flat acceleration output from DC to 100 Hz (200 Hz option)
- In addition to the borehole instrument with single jaw hole-lock, there is a 76 mm diameter option suitable for posthole installation with sand backfill to minimise convection
- Waterproof and durable with O-ring seals throughout
- Dual output (high and low gain) and optional high/low pass filters
- Optional electronic compass module to determine downhole attitude
- Remote DC offset zeroing
- Strain relief mechanism fully isolates the sensors from any motions in the load-bearing cable
The 3T borehole system designed for borehole diameters of 99 to 203 mm
The 3T Borehole (3TB) offers reliable, high quality performance in long period monitoring applications.
- Covers the complete seismic spectrum with a single transfer function
- 120 s to 50 Hz or 360 s to 50 Hz, other bespoke options available on request
- Hybrid velocity-acceleration responses available offering unrivalled dynamic range
- Single-jaw hole lock for inner borehole diameters of 99 to 203 mm, or backfill with sand to minimise convection
- Waterproof and durable with O-ring seals throughout
- Built-in inclinometer option for attitude checking at depth
- Operates with a tilt tolerance of up to 2.5 º with an option to increase this to 12.5 º
- Strain relief mechanism fully isolates the sensors from any motions in the load-bearing cable
Achieve exceptional dynamic range with this dual sensor 3T/5T borehole package
Acceleration and velocity monitoring in a single borehole instrument.
- Total realised dynamic range of over 200 dB with exceptionally low noise floor
- Simultaneous monitoring of both weak signals and high intensity shaking in a single system
- Single-jaw hole lock for inner borehole diameters of 99 to 203 mm, or backfill with sand to minimise convection
- Operates with a tilt tolerance of up to 2.5 º with an option to increase this to 12.5 º
- Waterproof and durable with O-ring seals throughout
- Built-in inclinometer option for attitude checking at depth
- Hole-lock units with cable pass-through available, allowing installation in boreholes already containing an instrument
- Strain relief mechanism fully isolates the sensors from any motions in the load-bearing cable
Downhole Minimus
For deployments exceeding 100 metres in depth, we recommend the Downhole Minimus digitiser. Digitizing the data at source ensures that the origin can be definitively
traced and not subject to attenuation during the travel to the surface; so signals are stronger and more reliable.
The Downhole Minimus, which integrates into the instrument to form a single unit, is an eight channel digitiser. It is connected via fibre optic cable to a surface interface unit which delivers advanced data processing capability and software communications, as well as allowing the user to access waveforms and state-of-health data at the installation location.
View our Very Broadband Borehole brochure:
