2018 TOUGH Symposium
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TReactMech Course

October 10, 2018 - October 12, 2018

TReactMech V1.0 Short Course

A TReactMech V1.0 Short Course will be held at Lawrence Berkeley National Laboratory, Berkeley, California. Note that space is limited and registration is on a first-come, first-served basis.
Registration Cost: General Attendee $1,250; Student $600

AGENDA

NOTES:

  • Information provided below is meant to give you a sense of what to expect during this course (but is subject to change).
  • This course is tentatively scheduled for October 10-12, 2018.
  • Space is limited and registration is on a first-come, first-served basis.

TReactMech V1.0 is a new 3-D coupled thermal-hydrological-mechanical-chemical (THMC) code that solves the continuum geomechanical stress and failure equations using a finite element formulation coupled to non-isothermal, multiphase/multicomponent fluid flow, heat transport, aqueous and gaseous species advection-diffusion, and equilibrium/kinetic water-gas-rock reactions. TReactMech combines a new geomechanics approach with the latest TOUGHREACT V3.30-OMP multiphase reactive-transport capabilities. Notable applications of TReactMech V1.0 are in the simulation of coupled THMC processes in Enhanced Geothermal Systems, geological CO2 sequestration, hydraulic fracturing in unconventional hydrocarbon reservoirs, nuclear waste isolation, injection/production-induced uplift/subsidence, and other subsurface problems involving geomechanical, hydrological, and geochemical processes. A wide range of spatial and temporal scales can be modeled from fracture deformation in lab experiments, hydraulic fracturing at scales of tens of meters around injection wells, to complex kilometer-scale problems involving hydrological, mineralogical, and chemical heterogeneity and crustal heat and fluid flow over geologic time scales. The course will focus on the basic formulations used in TReactMech, including poroelasticity, Mohr-Coulomb failure, and coupling of geomechanics to fluid pressure, heat transport, and fracture permeability changes. Hands-on example problems will focus on the set-up of hydro-geomechanical problems, stress-strain simulations involving poroelasticity, injection-induced fracture shear and tensile failure, and simple reactive-transport coupling. Pre-requisites include prior experience or courses in TOUGH2 or TOUGHREACT.

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A little more about TReactMech

TReactMech introduces a parallel coupled continuum geomechanics capability into the thermal-hydrological-(biogeo)-chemical (THMCB) parallel simulator TOUGHREACT V3.X-OMP (Sonnenthal et al., 2014; 2017; Xu et al. 2011; 2006), with improvements to the TOUGH2 multiphase flow core (Pruess et al., 1999). The geomechanical formulation is based on a 3-D continuum finite-element model with full 3-D stress calculations, plastic deformation via shear and tensile failure (Kim et al., 2012; 2015; Smith et al., 2015). Applications of TReactMech to Enhanced Geothermal System stimulation modeling and THMC experiments on rock cores are presented in Sonnenthal et al. (2015, 2018), Kneafsey et al. (2016, 2017).

TReactMech is ideally suited for continuum representations of fractured and porous rock masses at scales of meters to tens of kilometers. However, TReactMech can also simulate processes at the scale of individual fractures, such as for simulating hydraulic fracturing, or single-fracture deformation at the core-scale. The continuum model approach considers local (grid-block scale) averaging of fracture porosities, permeabilities, and other properties, in comparison to discrete fracture models (DFM) that capture fracture aperture changes typically using statistical realizations of fracture size distributions and orientations.

In TReactMech, heat and fluid flow, stress, and reactive transport are solved using the sequential non-iterative approach, as shown below. Fluid flow and heat transport are solved simultaneously as in TOUGH2 (Pruess et al., 1999) with modifications to consider multiple coupled geochemical and geomechanical effects on porosity and permeability, as well as new capabilities such as temperature-dependent thermal properties. TReactMech uses a hybrid parallel computation approach, in which the geomechanics are solved using Petsc/MPI and the reactive chemistry with OpenMP. Geomechanics (3D stress equations, strain and failure strain) are solved after fluid and heat flow, followed by transport of aqueous and gaseous species, mineral-water-gas reactions, and finally permeability-porosity-capillary pressure changes owing to geomechanical and geochemical changes to porosity (or fracture aperture).

TReactMech flowchart (left). Simulation of predicted permeability changes for a multi-well combined tensile and shear failure EGS stimulation (Sonnenthal et al., 2018).

 

Details

Start:
October 10, 2018
End:
October 12, 2018