Extension of TOUGH-FLAC to the finite strain framework

• Published in: Computers & geosciences 2017-11, Vol.108 (C), p.64-71
• Main Authors: Blanco-Martín, Laura, Rutqvist, Jonny, Birkholzer, Jens T.
• Format: Article
• Language: English
• Subjects: Coupled THM processes; Earth Sciences; Finite strains; FLAC3D; Sciences of the Universe; Sequential modeling; TOUGH2; Voro
• ISSN: 0098-3004; 1873-7803
• DOI: 10.1016/j.cageo.2016.10.015

The TOUGH-FLAC simulator for coupled thermal-hydraulic-mechanical processes modeling has been extended to the finite strain framework. In the approach selected, this extension has required modifications to the flow simulator (TOUGH2) and to the coupling scheme between the geomechanics and the flow sub-problems. In TOUGH2, the mass and energy balance equations have been extended to account for volume changes. Additionally, as large deformations are computed by FLAC3D, the geometry is updated in the flow sub-problem. The Voronoi partition needed in TOUGH2 is computed using an external open source library (Voro++) that uses the centroids of the deformed geomechanics mesh as generators of the Voronoi diagram. TOUGH-FLAC in infinitesimal and finite strain frameworks is verified against analytical solutions and other approaches to couple flow and geomechanics. Within the finite strain framework, TOUGH-FLAC is also successfully applied to a large-scale case. The extension of TOUGH-FLAC to the finite strain framework has little impact to the user as only one additional executable is needed (for Voro++), and the input files and the workflow of a simulation are the same as in standard TOUGH-FLAC. With this new provision for finite strains, TOUGH-FLAC can be used in the analysis of a wider range of engineering problems, and the areas of application of this simulator are therefore broadened. •TOUGH-FLAC simulator for coupled THM analyses extended to finite strain framework.•TOUGH2: balance equations extended to include volume changes and geometry update•Simulator validated against closed-form solutions and other codes and approaches.•Voronoi partition always used in TOUGH2, recalculated from FLAC3D mesh using Voro++.•New version of TOUGH-FLAC can be used in a wider range of engineering problems.