Monday, June 1, 2015
HG E22, 13:00 - 13:30

Modeling of Inelastic Strain Induced by CO2 Injection; Victor Vilarrasa (EPFL, Switzerland)

Co-Authors: Lyesse Laloui (EPFL, Switzerland)

Inelastic strain, which is associated to the induced microseismicity observed in CO2 injection sites like Weyburn or In Salah, is likely to occur in CO2 storage sites. Furthermore, CO2 will reach the storage formation at a colder temperature than the rock, which will induce a thermal stress reduction. We model non-isothermal injection of CO2 in a deep saline formation using the fully coupled finite element code CODE_BRIGHT. We find that despite inelastic strain is likely to occur in the cooled region around the injection well, fracture propagation does not extend into the caprock in the normal faulting stress regime simulated in this study.

Monday, June 1, 2015
HG E22, 13:30 - 14:00

CFD Computations of a Cavitation Vortex Rope; Jean Decaix (HES-SO//Valais-Wallis, Switzerland)

Co-Authors: Sebastien Alligné (Power Vision Engineering Sàrl, Switzerland); Andres Müller (EPFL, Switzerland); Cécile Münch (HES-SO//Valais-Wallis, Switzerland); François Avellan (EPFL, Switzerland)

Due to the increase in renewable energies in the electricity market, hydraulic power plants have to run at off-design operating points. For Francis turbines, this leads to the formation of a vortex rope known to promote cavitation surge. If the flow discharge is higher than the nominal one, an axisymmetric cavitation vortex rope develops in the draft tube cone. Such a vortex rope leads to high pressure fluctuations that interact with the entire power plant and limit the range of operating points. To better understand the physics of the phenomenon and to provide input to 1D models, two-phase 3D CFD calculations are performed and compared with experimental data

Monday, June 1, 2015
HG E22, 14:00 - 14:30

Challenges of Simulating Geothermal Reservoir Processes; Julian Mindel (ETH Zurich, Switzerland)

Co-Authors: Thomas Driesner (ETH Zurich, Switzerland)

Future geothermal power production in Switzerland requires circulating water through deep (~ 5km), fractured rock masses at temperatures exceeding 180°C. The extreme conditions massively limit direct, in situ observation and steering of reservoir processes, making numerical simulation a key research and development technology. The biggest challenges are a combination of complex but poorly know geometries (thin, irregular fracture networks in a large rock mass) and strongly coupled, non-linear processes (thermo-hydro-mechanical-chemical interactions). This contribution outlines the goals and challenges of numerical code development in the SCCER-SoE and related initiatives.

Monday, June 1, 2015
HG E22, 14:30 - 15:00

A New Volcanic Hydrothermal System in Java; the Lusi Mud Eruption and Aftermath; Stephen Miller (University of Neuchatel, Switzerland)

Co-Authors: Maïté Faubert (University of Neuchatel, Switzerland); Reza Sohrabi (University of Neuchatel, Switzerland)

In 2006 a magnitude 6.3 earthquake occurred in Yogyakarta on the island of Java. This relatively shallow earthquake resulted in 20,000 deaths and widespread destruction of the city. About 48 hours later, in the town of Sidoarjo about 250 km from the earthquake epicentre, mud began to spill out onto the surface and Lusi was born. Eruption rates peaked at 180,000 cubic meters of mud per day, and continues today as a vigorous geyser system, with geochemistry studies showing that is a geologic rarity of a newborn tectonic-scale hydrothermal system linked to the nearby volcano complex. We are modelling this system to gain insight of its workings and the possible exploitation of geothermal energy.

Monday, June 1, 2015
HG E22, 15:30 - 16:00

Modeling 3D THM Processes in Geothermics with Continuum Mechanics; Gunnar Jansen (University of Neuchatel, Switzerland)

Co-Authors: Reza Sohrabi (University of Neuchatel, Switzerland); Boris Galvan (University of Neuchatel, Switzerland); Stephen A. Miller (University of Neuchatel, Switzerland)

The geothermal community is challenged by the Energy Strategy 2050 goal to uncover the potential of renewable energy resources in Switzerland. To this end we implement a novel finite element based simulation tool for rock and fluid physics. It efficiently couples the dominant processes in the subsurface, such as fracture nucleation and growth using continuum mechanics, anisotropic multiphase fluid flow and heat transfer to provide a deeper understanding. We aim at state of the art performance by using massively parallel tools and modern accelerator techniques. We present first results from 3D fully coupled THM-simulations and evaluate the performance from a series of benchmark simulations.

Monday, June 1, 2015
HG E22, 16:00 - 16:30

Prediction of Elastostatic Friction for Rock-Like Surfaces with FEM; Alessandro Rigazzi (Università della Svizzera italiana, Switzerland)

Co-Authors: Rolf Krause (Università della Svizzera italiana, Switzerland)

We present the results of our recent work, in which we apply the Finite Element Method to study the frictional forces resulting from the elastostatic interactions of surface asperities. To do this, we generate several self-affine rough surfaces that are statistically similar to rock surfaces. Such surfaces are used as rigid obstacles onto which an elastic smooth cube is pushed and sheared to measure the maximal resistance opposed by the asperities. The contact problem gives rise to a huge nonsmooth system of equations. We solve this system with a solver based on our nonsmooth multigrid algorithm of optimal complexity for which we investigate scaling properties.

Monday, June 1, 2015
HG E22, 16:30 - 17:00

Modeling Induced Seismic Hazard During Geothermal Reservoir Creation; Joseph Doetsch (ETH Zurich, Switzerland)

Co-Authors: Valentin Gischig (ETH Zurich, Switzerland); Dimitrios Karvounis (ETH Zurich, Switzerland); Stefan Wiemer (ETH Zurich, Switzerland)

To enable the large-scale exploitation of deep geothermal energy for electricity generation in Switzerland, solutions must be found for two fundamental and coupled problems: (1) How to create an efficient heat exchanger in the hot underground that can produce energy for decades and (2) at the same time keeping the risk posed by induced earthquakes to acceptable levels' Numerical simulations of different complexity and physical detail are currently being developed for an Advanced Traffic Light System (ATLS) to predict the risk of in induces earthquakes in real-time. This contribution presents developments of the induced seismicity prediction codes towards high performance computing.

Monday, June 1, 2015
HG E22, 17:00 - 17:30

Silt Erosion Simulation Using Finite Volume Particle Method; Ebrahim Jahanbakhsh (EPFL, Switzerland)

Co-Authors:

Silt erosion is a destructive phenomenon that may occur in hydropower plants. This work presents a new erosion prediction model in which, fluid flow and solid deformation equations are discretized by Finite Volume Particle Method (FVPM), and silt contact forces are calculated according to Hertz contact theory. FVPM is a meshless method which includes many of the desirable features of the mesh-based finite volume method. To obtain a more accurate and robust model, a new FVPM formulation is presented in which particle interaction integrals are evaluated exactly and efficiently. To validate the new silt erosion model, 2D and 3D erosion cases are simulated and compared with experimental data.