Subcritical crack growth behavior of clay‐rich unconventional tight rocks under water‐saturated conditions

Hydraulic fracturing is the most widely used primary method for stimulation of unconventional oil and gas resources. While knowledge hydraulic fracture parameters critical to reservoir productivity, predicting initiation important determining complexity network. Subcritical crack growth in rock plays an role forming networks, but understanding influence conditions on subcritical still lacking. In this paper, behavior sandstone shale under ambient air, deionized (DI) water, slick-water studied. X-ray diffraction analysis done samples determine their mineralogical composition, while tensile strength measured by Brazilian test. Then Load Relaxation mode, a Double-Torsion test (DT) carried out different study samples. To further verify clay-rich minerals, similar performed clay-free granitic The results DT demonstrate that presence clay minerals main reason difference DI water seems better improve compared with other conditions. value Index (n) smaller environment than environment, revealing slick can promote complex propagation.