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Robertson Geo • High Resolution Acoustic Televiewer (HRAT)

Product Type
Wireline Logging Tool
Product Snapshot
Product Name
High Resolution Acoustic Televiewer (HRAT)
Product Type
Wireline Logging Tool
Robertson Geo
Rent ● Equipment & Operator
Robertson Geo's High Resolution Acoustic Televiewer (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 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.
Features & Applications
  • Fracture identification and orientation
  • Stratigraphic studies
  • Local stress studies (break-out)
  • Core orientation
  • Cased-hole studies
Operating Conditions
Borehole Type
Fluid filled
Logging Speed
Probe Specifications
42 mm
Length (Assembled)
1.55m or 1.99m (with natural gamma option)
Weight (Assembled)
Transducer Type
1.5MHz piezo-composite
Up to 360/rev
Launch & Recovery
Related Products
Robertson Geo's High Resolution Optical Televiewer (Hi-OPTV) provides a continuous very high resolution oriented image of the borehole walls using a conventional light source. A unique optical system based on a fisheye lens allows the probe to survey 360 degrees simultaneously. This information is processed in real time to produce a complete 'unwrapped' ... Moreimage of the borehole oriented to magnetic north. The probe offers superior resolution to the High Resolution Acoustic Televiewer (HRAT) and produces images in real colour. While, unlike the HRAT, it can operate in air-filled boreholes, it is unsuitable for boreholes containing mud or cloudy fluids.

WellCad™ Image-Processing Software
WellCad™ is a Windows-based package for processing, interpreting and displaying acoustic and optical televiewer image logs. Standard log presentations include tadpole and stick plots, stereographic projections of poles to planes and azimuth frequency diagrams. The synthetic core display allows convenient comparison of log and field data for orientation of fractured or incomplete core sections.
Robertson Geo's 3-Arm Caliper probe provides a single continuous log of borehole diameter, as recorded by three mechanically coupled arms in contact with the borehole wall. 710mm, 1000mm and 1500mm range calipers are available to suit a range of well diameters. The caliper is a useful first log to determine the borehole conditions before running more ... Morecostly probes or those containing radioactive sources.

Principle of Measurement
Opening and closing of the motor-drivercaliper arms is by surface command, allowing the probe to run into the borehole with the arms retracted. Once opened, the spring-loaded arms respond to borehole diameter variations as the probe is raised up the borehole.
Robertson Geo's Density Guardlog probe uses dual shielded detectors to provide a borehole compensated density measurement with good bed-boundary resolution, similar to the Formation Density probe. The Density Guardlog probe offers an additional LL3 focussed electrical measurement with good vertical resolution and depth of investigation.... More

Principle of Measurement
The Density Guardlog probe contains a detachable 137Cs gamma source and two scintillation gamma detectors. The active windows of the source and detectors are maintained in contact with the borehole wall by a motorised caliper arm. Gamma radiation back-scattered by the formation (Compton effect) reaches the detectors where the relative count rates provide a measure of formation density.
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+44 1492 582323