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HRAT-LU (Logging tool)


Model id: Robertson Geologging High Resolution Acoustic Televiewer (HRAT)

Measurements:

  • travel time of an acoustic signal
  • amplitude of an acoustic signal
  • probe orientation derived from magnetometer and accelerometer/gravimeter data
  • total natural gamma

Purpose: geological structures: bedding, foliation, lamination, natural & induced fractures, breakouts, high-resolution oriented borehole calliper, borehole trajectory, casing inspection

Description: The HRAT provides a continuous high-resolution oriented ultrasound image of the borehole wall. The probe uses a fixed acoustic transducer and a rotating acoustic mirror to scan the borehole walls with a focussed ultrasound beam. The amplitude and travel time of the reflected acoustic signal are recorded as separate image logs. Features such as fractures reduce the reflected amplitude and appear as dark sinusoidal traces on the log. The travel-time log is equivalent to a high-precision 360-arm caliper and shows diameter changes within open fractures and ‘break-outs’. Directional information is also recorded and used to orient the images in real time. Interpretation software is available for detailed analysis of the displayed features and includes conventional arrow (tadpole) plots, stereograms of feature orientations and synthetic core images.

Characteristics: Transducer type: 1.5MHz piezo-composite; Rotation rate: 5 – 20rev/s; Sample rate: up to 360/rev

Specifications:

Vertical resolution:0.002 m
Typical logging speed:2.00 m/min
Maximum pressure:20.0 MPa
Maximum temperature:70℃
Required boreholefluid:
liquidThe borehole has to be filled with some sort of liquid.
Minimum borehole diameter:0.070 m
Maximum borehole diameter:0.180 m
Centralisation required:yes
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Type of datatransfer:
cableData are transferred in real time via a cable.
Required type of logging cable:
4 conductorA logging cable with 4 conductors.
Required cablehead:
GO4Connector according to GO 4 standard (4 conductors).
Implement search on winches with this cable head.
Type of signal:
digitalDigital signal transmission.
Maximum cable length:2000 m
Acquisitionsystem (recommended):RG-LU
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Length:2.06 m
Maximum diameter:0.042 m
Weight:6.5 kg
Belongs to toolstring:
standaloneA stand alone tool that cannot be integrated in a tool string.
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Usage conditons:Commercial usage allowed/welcome.
Additional usage conditions:Logging as service by Lund University

Operator and contact:

Operator:Lund University, Engineering Geology
Contact person:Per-Gunnar Alm
Email:per-gunnar.alm@tg.lth.se
Telephone:+46 462228992
Address: John Ericssons väg 1
223 63 Lund, Sweden


End of I-EDDA database record