Current industry practices to determine rock tensile strength employ either the Brazilian method or the encumbered epoxied-grapple hook method. Neither method directly tests the stresses needed to induce tensile fractures in the rock matrix, a key petrophysical property in petroleum engineering necessary for hydraulic fracturing. The test developed by this research directly determines the tensile strength of rock with a novel strategy that achieves over-pressurized pore fluids via an adjustable confining stress schedule to induce tensile micro-fractures. Failure is defined by displacement, microfracture initiation, as indicated by strain gages adhered to the specimens. The pore over-pressurization method proves effective for creating tensile fractures in rocks with both milli-and micro-darcy level permeability. Results indicate tensile strengths ranging from 40 to 220 psi (0.3 MPa to 1.5 MPa) for Oriskany Sandstone and 650 psi (4.5 MPa) at 300 psi/min and 180 psi (1.2 MPa) at 600 psi/min for Salem Limestone. The directness of this methodology for tight rock provides a viable alternative to the limitations and biases of indirect testing m
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