Combined effects of high temperature and lithology on the tensile mechanical damage and fracture surface morphology of reservoir rocks

Understanding the influence of high temperature on reservoir rocks is necessary for the repair and reinforcement of high-temperature rock engineering. In this study, X-ray diffraction (XRD) tests, scanning electron microscope (SEM) tests, Brazilian splitting tests, and morphological scanning tests were performed on Cretaceous granite (CG), Jurassic granite (JG), and Jurassic sandstone (JS) after high temperature (25 900 °C) treatment. These tests aimed to analyze their mineral composition, microstructure, tensile mechanical damage, and morphological parameters. The results indicate that as temperature rises, the volume of the rocks generally increases, accompanied by a rise in tensile strength damage, reaching 75.4