01-06-2024 | Original Paper
Combined effects of high temperature and lithology on the tensile mechanical damage and fracture surface morphology of reservoir rocks
Authors:
Peng Zhang, Cong Wang, Zhen Gao, Zhihe Wang, Changtai Zhou, Fei Wang
Published in:
Bulletin of Engineering Geology and the Environment
|
Issue 6/2024
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Abstract
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% ~ 98.1% at 900 ℃. Notably, the same heat treatment causes the most damage to dense JG and the least damage to porous JS. These findings are related to the microcracks in the samples caused by mineral expansion, as verified in their microstructure. Moreover, with increasing temperature, the height parameter (Sz), roughness parameters (Sa and Sq), and power spectral parameters of the fracture surface morphology for three lithologies decrease to the minimum at 300 °C and then increase, except for the continuous increase in roughness parameters of JG. These trends are attributed to the combined effect of high temperature-induced mineral expansion and the initial structure of lithology. Furthermore, the surface morphology fractal dimension of CG and JG reaches the maximum at 900 °C, while that of JS reaches its smallest, likely due to the single mineral component present in JS.