: A new experimental apparatus was developed in order to measure the geomechanical properties of rock samples. The main feature of this triaxial cell is that radial and axial deformations are measured using four laser beams. No more contact transducers are attached to the sample (strain gauges or LVDT) affecting the accuracy of the measurements. Thanks to this Laser Cell, new and more accurate measurements are possible especially on loose sandstone or shaly samples. The main fields of application of the Laser Cell are high accuracy geomechanical characterization of loose geomaterials, sand production prevention, subsidence evaluation, compaction measurement of sedimentary basins and mechanical testing of side wall cores.
The geomechanical characterization of loose materials, hard soils, compacted sands, or unconsolidated shales is nowadays a very critical point in rock mechanics, related to hydrocarbon exploration and production activities. Compression tests (isotropic, uniaxial or triaxial) are the state of the art in order to simulate and predict, in the laboratory, the in-situ behavior or rock formations. The main drawback of loose geomaterials testing is the accuracy of sample deformation measurement. The high stress levels to impose on rock specimen coming from deep wells (thousands of meters of depth) require that test equipment can not house pressure sensible transducers. A new approach to conduct deformation measurement during triaxial tests is nowadays possible.