Australia's geothermal frontier: Unlocking Granite's energy secrets
Publication Name
Geoenergy Science and Engineering
Abstract
Comprehending the temperature-dependent mechanical behaviour of reservoir rocks under cyclic heating and cooling conditions holds significant implications for various deep-earth engineering applications, namely deep geothermal energy recovery, deep nuclear waste disposal, and coal gasification. In this study, the thermo-mechanical behaviour of Australian Harcourt granite is examined through a cyclic heating and quenching process. A series of comprehensive experiments were conducted to analyse the stiffness of the material, across a range of temperatures (20 °C–900 °C) and quenching cycles (1–15 cycles). The fracture distribution resulting from quenching cycles was investigated using Micro-CT scanning, while acoustic emission technology was employed to examine the fracture development, propagation, and failure process during shearing. The findings revealed that as temperature and heating/cooling cycles increased, the compressive strength, Young's modulus, shear modulus, crack damage threshold, and brittleness index exhibited a reduction. Conversely, the strain at failure and Poisson's ratio showed an increase. The cyclic quenching treatment resulted in significant rock degradation, as observed through increased porosity and cumulative acoustic emission counts with higher temperatures and heating/cooling cycles. These observations suggest that the granite transitions from a brittle to a “quasi-brittle” state as temperature and thermal cycles increase, signifying further evolution in its mechanical behaviour.
Open Access Status
This publication is not available as open access
Volume
234
Article Number
212665
Funding Number
18562