Methodology and Preliminary Testing of Rocks Under Volumetric Compression Using the MDS-450 and MTS-815 ServoHydraulic Systems

This methodological paper describes the development and preliminary validation of an experimental procedure for testing rock specimens under volumetric compression using the MDS-450 and MTS-815 servo-hydraulic systems. The apparatus allows the simultaneous application of axial load, confining pressure, pore pressure, and temperature to simulate thermobaric conditions corresponding to depths of about 10–12 km. In this study, the system was used only under room-temperature conditions in order to verify the loading path and data acquisition scheme. The procedure provides stepwise reproduction of reservoir conditions and is designed to record triaxial compressive strength, deformation moduli, dilatancy, and acoustic and ultrasonic responses. Results from preliminary tests on sedimentary rock specimens at confining pressures of 90 and 120 MPa and room temperature demonstrate typical stages of volumetric compression and confirm the stability of the experimental method. To support the verification of the methodology, additional tests were also performed at a confining pressure of 50 MPa, incorporating the temperature factor and acoustic emission monitoring.