Coupled thermal-hydraulic simulations of fracturing in granite under high temperature and high pressure treatment via peridynamic. (December 2022)

• Record Type: Journal Article
• Authors: Yang, Zhen; Yang, Sheng-Qi; Zheng, Wenbo; Tannant, Dwayne D.
• Is Part Of: International journal of rock mechanics and mining sciences. Volume 160(2022)
• Publication Date: 2022-12
• Subjects: Ordinary state-based peridynamics -- Thermo-mechanical coupling -- Granite -- Improved multi-layer computational method -- Fracturing -- High-temperature and high-pressure treatment; Rock mechanics -- Periodicals; Soil mechanics -- Periodicals; Mining engineering -- Periodicals; Roches, Mécanique des -- Périodiques; Sols, Mécanique des -- Périodiques; Technique minière -- Périodiques; 624.151305
• DOI: 10.1016/j.ijrmms.2022.105247
• Languages: English
• ISSNs: 1365-1609

Abstract

Abstract: This paper described an improved multi-layer computational method based on fully coupled thermal-mechanical ordinary state-based peridynamics (OSB-PD), which enables simulating fracturing in granite under coupled thermal-hydraulic effects. Four computational layers, i.e., pre-treatment thermal layer (PTL), mechanical loading layer (MLL), interactive thermal layer (ITL), and hydraulic mechanical layer (HML) were included in this method. PTL was used to simulate the heterogeneity of granite materials by creating initial pre-existing microcracks. MLL was utilized to apply borehole pressure, while ITL was designed to generate real-time thermal forces. HML was employed to apply equivalent hydraulic pressure to cracks, and distinguish between thermal-induced and hydraulic-induced damage. Two verification cases, including hydraulic fracturing and sleeve fracturing of granite specimens at different pressurization rates, as well as the steady-state heat conduction of a hollow cylindrical specimen, were simulated to investigate the convergence, capability and accuracy of the numerical method. The proposed method was then applied to the hydraulic fracturing of granite under high temperature and high pressure (HTHP) treatment. The complex interactions among natural pre-existing microcracks, thermal-induced microcracks and hydraulic-induced cracks was properly predicted. The effect of cold water (temperature gradient) on the fracture morphology and breakdown pressure of granite specimens was also discussed. A systematic comparison with the experimental results shed lights to the failure mechanisms of granite specimens subjected to HTHP hydraulic fracturing tests.