Project

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Unraveling the attenuation and velocity dispersion of seismic waves in complex fractured media by means of multilevel simulations

Applicant Favino Marco
Number 180112
Funding scheme Ambizione
Research institution Institut des sciences de la Terre Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Mathematics
Start/End 01.12.2018 - 30.11.2022
Approved amount 556'272.00
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All Disciplines (2)

Discipline
Mathematics
Geophysics

Keywords (7)

Biot's equations; Seismic attenuation and velocity dispersion; Multilevel Monte Carlo; Random Fracture Networks; Multigrid; Fluid pressure diffusion; Adaptive mesh refinement

Lay Summary (Italian)

Lead
Un'onda sismica che si propaga attraverso rocce porose con sistemi di fratture è soggetta a fenomeni di attenuazione e dispersione dovuti alla diffusione del fluido presente all'interno delle stesse formazioni rocciose. La caratterizzazione sismica di questo tipo di rocce permette di comprendere le loro proprietà geometriche, meccaniche e idrauliche. Poiché le misurazioni dirette forniscono solo informazioni parziali, il ricorso a modelli matematici e a metodi numerici di simulazione risulta fondamentale.
Lay summary
Ad oggi, la simulazione dell'accoppiamento idromeccanico in rocce con reti di fratture aventi geometrie realistiche non è possibile a causa dell'elevato costo di calcolo. L'obiettivo di questo progetto è di sviluppare efficienti metodi di soluzione multilivello, che sfruttano modelli surrogati per accelerare la simulazione di modelli accurati, permettendo quindi di realizzare simulazioni stocastiche con un grande numero di campioni. In particolare, verranno sviluppati un metodo di soluzione multigriglia e un metodo Monte Carlo multilivello. Per i modelli surrogati verranno utilizzate griglie lasche che derivano da una strategia di raffinamento adottivo, che permette di descrivere con accuratezza crescente la geometria delle fratture. Successivamente, i dati sperimentali disponibili verranno sfruttati per una calibrazione ottimale dei modelli fisici, utilizzando strategie di assimilazione dei dati.
Questo progetto di frontiera nella ricerca in geofisica avrà importanti ricadute in diversi campi di applicazione,
quali la produzione di energia geotermica, la ricerca di depositi di idrocarburi e lo stoccaggio di scorie nucleari. In particolare, in Svizzera il passaggio all'energia geotermica è uno degli obiettivi della Strategia energetica 2050.
 
Direct link to Lay Summary Last update: 23.08.2018

Responsible applicant and co-applicants

Employees

Publications

Publication
Fully-automated adaptive mesh refinement for media embedding complex heterogeneities: application to poroelastic fluid pressure diffusion
Favino Marco, Hunziker Jürg, Caspari Eva, Quintal Beatriz, Holliger Klaus, Krause Rolf (2020), Fully-automated adaptive mesh refinement for media embedding complex heterogeneities: application to poroelastic fluid pressure diffusion, in Computational Geosciences, 24(3), 1101-1120.

Collaboration

Group / person Country
Types of collaboration
Prof. Fabio Nobile, EPF Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Cornelis W. Oosterlee, TU Delft Netherlands (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Francisco Gaspar, University of Zaragoza Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Klaus Holliger, University of Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Chemnitz Finite Element Symposium Talk given at a conference An accuracy condition for the finite element discretization of Biot's equations 09.09.2019 Mülheim an der Ruhr, Germany Favino Marco;
SCCER-SoE Annual Conference Talk given at a conference Hydromechanical Coupling in Heterogeneous and Fractured Media 03.09.2019 Lausanne, Switzerland Favino Marco;
X-DMS Conference on eXtended Discretization MethodS Talk given at a conference Multigrid Methods for Complex Fracture Networks in Porous Media 03.07.2019 Lugano, Switzerland Favino Marco;


Self-organised

Title Date Place

Abstract

Recent advances in numerical mathematics and data assimilation allow for realistic simulations and for accurate calibrations of mathematical models, from which a wide range of novel applications stand to profit. One research field that would substantially benefit from advanced simulation techniques is the geometric, mechanical, and hydraulic characterization and fracture networks in the Earth's crust, which is widely regarded as a major scientific and technical frontier. Knowledge of the mechanical and hydraulic behavior of fractured rock formations is essential for a wide variety of important practical applications, such as, for example, geothermal energy production, hydrocarbon exploration, nuclear waste storage, and CO2 sequestration. Since the characterization of fractures by means of direct observations is generally not possible, indirect approaches based on mathematical models are of pre-eminent importance. A particularly promising avenue in this regard is the realistic numerical simulation of the effects of fractures on the propagation of seismic waves in fluid-saturated porous rocks. Notably, there is recent evidence to suggest that relating the attenuation and the velocity dispersion of seismic waves to the underlying fluid pressure diffusion process has the potential of revealing essential information about the geometric and physical properties of fracture networks.To date, numerical simulations of realistic three-dimensional fracture networks are not possible due to the associated computational cost. A cheaper alternative is to model fractures as lower-dimensional manifolds in which only fluid flow is considered. However, this approach does not adequately account for the hydro-mechanical coupling in the fractures which in turn has prominent effects on the resulting attenuation and velocity dispersion. To overcome these fundamental limitations, I propose a interdisciplinary project aiming at the efficient simulation of three-dimensional random fracture networks. Specifically, I will adapt multilevel strategies to the solution of this specific problem. The two main ingredients will be a multigrid solver and a multilevel Monte Carlo method, which in turn will greatly enhance the efficiency of the numerical simulations. My work will provide a novel numerical tool for the seismic characterization of fractured rocks, which will ideally complement and reinforce related ongoing projects in the context of deep geothermal energy production at the host institution and at the national level, notably within the context of the Swiss Compentence Center for Energy Research or SCCER (www.sccer-soe.ch).The realization of this project will greatly benefit from my experience and expertise in poroelasticity and in the application of high-performance solvers to real-world problems. It will also allow me to further sharpen my scientific profile and to develop it towards the independence required by the next career step. The project will be hosted at the Institute of Earth Sciences of the University of Lausanne, where the research group of Prof. Klaus Holliger pursues related objectives from an applied geophysical perspective. While the choice of the host institution is ideal for the transfer of knowledge and technology, the collaboration with Prof. Fabio Nobile, Chair of Scientific Computing and Uncertainty Quantification at EPFL, will greatly strengthen the theoretical and methodological aspects of the proposed research.
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