Both versions of the BHTV42 acoustic televiewer tool employ a rotating transducer mounted at the lower extremity of the tool to send a highly focussed ultrasonic pulse radially outwards towards the borehole wall up to 360 times per revolution, the amplitude and travel time of which are measured on its return to the probe after reflection at the borehole wall.
This information, combined with the data given by the tool’s onboard orientation system, provides an extremely detailed and orientated acoustic image of the borehole wall.
A high-temperature variant, the BHTV42-HT, can operate at up to 125°C.
BHTV42 SPECIFICATIONS
Technical Specifications
✓ Diameter : 42 mm
✓ Length : 2100 mm
✓ Weight : 8 Kg
✓ Housing : titanium and non magnetic brass
✓ Max. Temp : 70°C/100°C for BHTV42-HT
✓ Pressure : 200 bar
Sensors Parameters
✓ Transducer type : 1 inch focussed piezocomposite sensor and rotating mirror
✓ Signal frequency : 1.5 MHz
✓ Acoustic beam angle : 3° (3dB) conical
✓ Rotation speed : Up to 20 revolutions per second
✓ Orientation : Triple magnetometers / accelerometers
✓ Amplification : 0 to 60 dB, in 1 dB steps and AGC
✓ Pulses per resolution : 90, 120, 180 or 360 (horizontal definition)
✓ Vertical definition : Unlimited, determined by logging speed
✓ Orientation accuracy : ± 0.5° dipping ; ± 1.0° azimuth
Options And Accessories
✓ Gamma ray sensor: ø25 x 50 mm NaI(Tl) crystal
✓ Centralisers non-magnetic
✓ Bowspring centralisers
✓ Centraliser collar
✓ Weighter (load)
✓ Verticality calibrator
Borehole Conditions
✓ Fluid-filled open borehole: : water or light bentonite mud
✓ Probe must be centralised
✓ Recommended diam. range : 75 – 300 mm
