Method, apparatus and system for estimation of rock mechanical properties

A system for measuring mechanical properties of a rock formation, the system comprising:

• a load frame device, the load frame device including actuators configured to apply opposing compressive forces to a disc-shaped sample of a core plug specimen from the rock formation;
• an extensometer device, the extensometer device including sensors to measure axial and lateral displacements of the disc-shaped sample when the opposing compressive forces are applied to the disc-shaped sample;
• and
• force application fixtures coupled to the actuators, wherein each of the force application fixtures include an applicant portion having an end cap, the end cap having a shaped surface that is configured to conform with a portion of a non-planar side of the disc-shaped sample such that substantially an entire volume of the disc-shaped sample experiences a compressive stress when the opposing compressive forces are applied to the portions of the non-planar side.

A method of measuring mechanical properties of a rock formation, comprising:

• providing a core plug specimen from the rock formation;
• dividing the core plug specimen into disc-shaped samples;
• successively placing each one of the disc-shaped samples into to an apparatus such that force application fixtures of the apparatus can apply opposing compressive forces to the disc-shaped samples such that substantially an entire volume of the samples is configured to experience a compressive stress,
• successively applying the opposing compressive forces to each of the disc-shaped samples, wherein for each of the disc-shaped samples, the opposing compressive forces are applied in directions that are at a different angles relative to a direction of in situ force experienced by the core sample;
• and
• successively measuring axial and lateral displacements of each of the disc shaped samples during the application of the opposing compressive forces until failure of the each of the disc-shaped samples is detected, wherein:
• the axial displacement is measured along a first axis, the first axis parallel to the directions of the opposing compressive forces, and the lateral displacement is measured along a second axis, the second axis perpendicular to the directions of the opposing compressive forces.