Description
The PREPEAK triaxial cell is designed to apply deviatoric stresses to the core sample, facilitating anisotropic stress states. It features a built-in hydraulic piston that applies an axial load on the specimen, allowing distinct radial and axial confining pressures to be applied. Unlike equipment designed for rock-failure testing, this cell is optimized for sub-failure loading where the rock remains intact. A wide range of advanced measurements—acoustic, petrophysical and mechanical—depend on stable, precisely managed stress states rather than inducing rock failure. Each unit can be custom-configured to meet specific requirements, offering a wide range of pressure capacities, temperature limits, specimen sizes, and test modules to provide a fully tailored solution. When corrosive fluids are used, the stainless-steel wetted parts can be substituted with Hastelloy components.
Specifications
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Pore pressure range
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0-70 MPa
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Confining pressure range | 0-70 MPa |
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Axial pressure range | 0-70 MPa |
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Deviatoric stress range | 0-70 MPa |
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Temperature range | -20 to 150°C |
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Sample diameter | up to 2 inches
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Sample length | Twice the length |
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Wetted part material
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Stainless steel / Hastelloy
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Loading
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Hydrostatic / Triaxial
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Port fittings | 1/8 inch
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Benefits
The PREPEAK triaxial cell enables a comprehensive series of geomechanical and petrophysical tests, providing detailed evaluation of deformation behavior, fluid‐flow properties, elastic responses, and fracture‐related processes under controlled laboratory conditions. These include:
* Creep and long-term deformation: involve constant-load compaction, time-dependent strain, and behaviors essential for simulating reservoir depletion.
* Rock compressibility: leads to stress-induced volume reduction and pore-structure compaction, resulting in a pressure-dependent storage capacity.
* Stress-dependent porosity: decreases due to pore-throat closure and compaction, which reduce the total void space available in the rock.
* Stress-dependent permeability: changes because the deformation of the pore network leads to anisotropic flow, restricting fluid movement differently in each direction.
* Acoustic velocity testing (Vp/Vs): reflects stress-dependent elastic properties influenced by microcrack closure and the development of anisotropy.
* Electrical resistivity: reflects stress-dependent conductivity driven by pore-structure evolution and changes in microcrack connectivity.
* Acoustic Emission (AE): captures microcrack initiation and damage evolution during sub-failure stress cycling.
* Hydraulic fracturing AE tests: monitor borehole pressurization to detect microcrack initiation and track subsequent fracture propagation.