The “PIK-ST” automated installation for core strength profile constructing (scratch-test)

The PIK-ST installation is designed to determine rock samples strength by cutting method.

 Analysis is based on cutting forces profiles recorded during core surface scratching process with a cutter placed on a movable carriage. The carriage is driven by a servo drive through a ball-screw transmission. Cutting depth is set by flywheel and is monitored by linear displacement sensor. The load occurring on the cutter is detected by accurate force sensor. Sensor register longitudinal and normal component of the cutting force. Rock strength characteristics are calculated from cut depth known values ​​and cutting forces.

 Depending on the used theory, core material availability and time, PIK-ST tests can be carried out under various programs. For a preliminary assessment of rocks strength properties, cutting force profiles can be used as correlation basis with rock strength parameter for uniaxial compression (UCS – unconfined compressive strength). In the case of extended research program, UCS values can be significantly clarified for the selected lithotypes, as well as values assessment of internal friction angle can be carried out for these lithotypes.

The software allows user to associate core strength with depth. There is a possibility of combining analysis of several wells in one card. Analysis results can be exported to a spreadsheet, compatible with Microsoft Office.

The installation can additionally be equipped with photographing unit for creating continuous core images and unit for measuring ultrasonic wave propagation velocities and determining samples elastic properties. The software allows user to superimpose strength and elastic sample properties profile on the resulting photo image for detailed and visual display of measurement results.
Measurement mode is automatic, that reduces human factor influence. The installation is controlled from a computer.