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Unconfined Compressive Strength Testing

Unconfined Compressive Strength Testing



  • Rock strength is crucial for designing any field development activity, whether drilling a wellbore, hydraulically fracking or assessing mechanical behavior of a reservoir that is already producing.
  • Uniaxial Compressive Strength/ Unconfined Compressive Strength (UCS) test is the simplest of the laboratory geomechanics tests that provide measure of strength and mechanical property (Young’s Modulus and Poisson’s Ratio).
  • No confining pressure, no need for pressure vessel - “unconfined” strength.
  • The sample diameter can be between 0.75 to 4 inches. with length being twice the sample diameter, per ASTM/ISRM standard.
  • The example test shown here reports peak stress achieved during the test as UCS of the rock sample with Young’s Modulus being the slope of the stress-strain plot at linear-elastic region, after closure of micro-cracks (if any) and before yield.


Recommended Sample Dimensions:


  • Length: 2” Diameter : 1”
  • Length: 3” Diameter: 1.5”
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