Mathematical Problems in Engineering
Volume 2017, Article ID 1290748, 13 pages
https://doi.org/10.1155/2017/1290748
CO2 Permeability Analysis of Caprock Containing a Single Fracture Subject to Coupled Thermal-Hydromechanical Effects
1State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China
2College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China
Correspondence should be addressed to Qian Yin; moc.liamxof@niyrej
Received 20 January 2017; Accepted 26 February 2017; Published 28 March 2017
Academic Editor: Sandro Longo
Copyright © 2017 Qian Yin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Coupled THM (thermal-hydromechanical) processes have become increasingly important in studying the issues affecting subsurface flow systems. CO2 permeability of the fracture in caprock is a key factor that affects sealing efficiency of caprock. A new model associated with coupled THM processes that shows a good reliability was derived. Then, based on the COMSOL multiphysics software, a series of numerical calculations were performed on caprock models with a single fracture subject to coupled THM effects. Transmissivity of the fracture as a function of fracture angle, overburden pressure, fluid pressure difference, injected CO2 temperature, and the initial fracture aperture was elucidated, respectively. Average transmissivity of the fracture undergoes an increase by 1.74 times with the fracture angle (45°–90°), 2-3 orders of magnitude with the fluid pressure difference (5–30 MPa), and 4-5 orders of magnitude with the initial fracture aperture (0.05–0.5 mm), while it decreases by 3-4 orders of magnitude as overburden pressure increases from 30 to 80 MPa. Injected CO2 temperature has a small impact on the fracture permeability. This work provides an alternative tool to enrich the numerical modeling for the assessment of CO2 caprock sealing efficiency.