Geotechnical Engineering

Fracture detection and analysis

The detection, location, orientation, and size of fractures are important in most geotechnical, hydrogeological and geological investigations. Acoustic and optical imaging are convenient and cost effective ways of obtaining such information. These techniques provide an orientated, ‘unwrapped’ image of the borehole walls which may be used for core orientation or after structure picking for detailed interpretations.

The Optical Imager contains a precision machined prism and high definition digital camera assembly which permits high quality images of the borehole wall to be recorded at 0.5mm intervals vertically and 720 pixels per 360° horizontally.

The Acoustic Imager produces an image of the borehole wall using the travel time and amplitude of an acoustic signal transmitted and received by the tool. The variance of the acoustic properties of the formation and associated features enable the nature of fractures, fissures, veins, bedding planes and lithological changes to be determined. The acoustic image below shows both fractures and steeply dipping bedding.