Philipp Schaedle Publications

Philipp Schaedle

PhD Student

daniel_vogler_234x323

Mailing Address
Philipp Schädle
Geothermal Energy & Geofluids
Institute of Geophysics
NO F 51.1
Sonneggstrasse 5
CH-8092 Zurich Switzerland

Contact
Phone +41 44 633 8059
Email philscha@ethz.ch

Administration
Dominique Ballarin Dolfin
Phone +41 44 632 3465
Email ballarin(at)ethz.ch

Publications

[Go to Proceedings Refereed]  [Go to Theses]

Underlined names are links to recent or past GEG members

REFEREED PUBLICATIONS IN JOURNALS

3. 
Schädle, P., P. Zulian, D. Vogler, S. Bhopalam R., M.G.C. Nestola, A. Ebigbo, R. Krause, and M.O. Saar 3D non-conforming mesh model for flow in fractured porous media using Lagrange multipliers Computers & Geosciences, 132, pp. 42-55, 2019. [Download PDF] [View Abstract]This work presents a modeling approach for single-phase flow in 3D fractured porous media with non-conforming meshes. To this end, a Lagrange multiplier method is combined with a parallel variational transfer approach. This Lagrange multiplier method enables the use of non-conforming meshes and depicts the variable coupling between fracture and matrix domain. The variational transfer allows general, accurate, and parallel projection of variables between non-conforming meshes (i.e. between fracture and matrix domain). Comparisons of simulations with 2D benchmarks show good agreement, and the applied finite element Lagrange multiplier spaces show good performance. The method is further evaluated on 3D fracture networks by comparing it to results from conforming mesh simulations which were used as a reference. Application to realistic fracture networks with hundreds of fractures is demonstrated. Mesh size and mesh convergence are investigated for benchmark cases and 3D fracture network applications. Results demonstrate that the Lagrange multiplier method, in combination with the variational transfer approach, is capable of modeling single-phase flow through realistic 3D fracture networks.

2. 
Schaedle, P., T. Kaempfer, G. Pepin, J. Wendling, and J. Bommundt Combining high-resolution two-phase with simplified single-phase simulations in order to optimize the performance of PA/SA simulations for a deep geological repository for radioactive waste Geological Society, London, Special Publications, 433/443/SP443.4, 2017. [Download PDF] [View Abstract]The transport of a radioactive solute during the transient thermo-hydraulic regime with gas generation in and around a disposal cell depends on complex multi-phase processes. Numerical simulations can improve the understanding of the system by providing detailed information on the temporal and spatial distribution of the radionuclides. In particular, their fluxes can be computed under the given transient conditions considering radionuclide, heat and gas release from the waste. However, such detailed multi-phase simulations are very demanding with respect to com- putational resources and time. Based on the knowledge gained from such complex simulations, we have developed a robust simplified single-phase approach for performance and safety assessment, the improved efficiency of which enables extensive parameter studies. The simplified approach comprises, on the one hand, homogenization of features of high detail and, on the other hand, the employment of two-phase simulation results that are used to deduce equivalent single-phase parameterizations. The results have been validated with various benchmark criteria at well-defined interfaces in the modelled disposal cells based on the simulated radionuclides fluxes.

1. 
Schaedle, P., N. Hubschwerlen, and H. Class Optimizing the modeling performance for safety assessments of nuclear waste repositories by approximating two-phase flow and transport by single-phase transport simulations Nuclear Technology/187(2), pp. 188-197, 2014. [Download PDF]


[back to Top of Page]

PROCEEDINGS REFEREED

2. 
Lima, M., P. Schädle, D. Vogler, M. Saar, and X.-Z. Kong A Numerical Model for Formation Dry-out During CO2 Injection in Fractured Reservoirs Using the MOOSE Framework: Implications for CO2-based Geothermal Energy Extraction , Proceedings of the World Geothermal Congress 2020, Reykjavík, Iceland, (in press). [View Abstract]Injection of supercritical carbon dioxide (scCO2) into geological reservoirs is involved in Carbon Capture, Utilization, and Storage (CCUS), such as geological CO2 storage, and Enhanced Geothermal Systems (EGS). The potential physico-chemical interactions between the dry scCO2, the reservoir fluid, and rocks may cause formation dry-out, where mineral precipitates due to continuous evaporation of water into the scCO2 stream. This salt precipitation may impair the rock bulk permeability and cause a significant decrease in the well injectivity. Formation dry-out and the associated salt precipitation during scCO2 injection into porous media have been investigated in previous studies by means of numerical simulations and laboratory experiments. However, few studies have focused on the dry-out effects in fractured rocks in particular, where the mass transport is strongly influenced by the fracture aperture distribution. In this study, we numerically model the dry-out processes occurring during scCO2 injection into brine-saturated single fractures and evaluate the potential of salt precipitation. Fracture aperture fields are photogrammetrically determined with fracture geometries of naturally fractured granite cores from the Deep Underground Geothermal (DUG) Lab at the Grimsel Test Site (GTS), in Switzerland. We use an open-source, parallel finite element framework to numerically model two-phase flow through a 2D fracture plane. Under in-situ reservoir conditions, the brine is displaced by dry scCO2 and also evaporates into the CO2 stream. The fracture permeability is calculated with the local cubic law. Additionally, we extend the numerical model by the Young-Laplace equation to determine the aperture-based capillary pressure. Finally, as future work, the precipitation of salt will be modelled by employing a uniform mineral growth approach, where the local aperture uniformly decreases with the increase in precipitated mineral volume. The numerical simulations assist in understanding the long-term behaviour of reservoir injectivity during subsurface applications that involve scCO2 injection, including CO2-based geothermal energy extraction.

1. 
Lima, M.M., P. Schädle, D. Vogler, M.O. Saar, and X.-Z. Kong Impact of Effective Normal Stress on Capillary Pressure in a Single Natural Fracture , European Geothermal Congress 2019, pp. 1-9, 2019. [View Abstract]Multiphase fluid flow through rock fractures occurs in many reservoir applications such as geological CO2 storage, Enhanced Geothermal Systems (EGS), nuclear waste disposal, and oil and gas production. However, constitutional relations of capillary pressure versus fluid saturation, particularly considering the change of fracture aperture distributions under various stress conditions, are poorly understood. In this study, we use fracture geometries of naturally-fractured granodiorite cores as input for numerical simulations of two-phase brine displacement by super critical CO 2 under various effective normal stress conditions. The aperture fields are first mapped via photogrammetry, and the effective normal stresses are applied by means of a Fast Fourier Transform (FFT)-based convolution numerical method. Throughout the simulations, the capillary pressure is evaluated from the local aperture. Two approaches to obtain the capillary pressure are used for comparison: either directly using the Young-Laplace equation, or the van Genuchten equation fitted from capillary pressure-saturation relations generated using the pore-occupancy model. Analyses of the resulting CO2 injection patterns and the breakthrough times enable investigation of the relationships between the effective normal stress, flow channelling and aperture-based capillary pressures. The obtained results assist the evaluation of two-phase flow through fractures in the context of various subsurface applications.


[back to Top of Page]

THESES

1. 
Schaedle, P. Rechenzeitoptimierung bei numerischen Sicherheitsabschätzungen für Atommüll-Endlager, MSc Thesis, University of Stuttgart, 82 pp., 2012. [View Abstract]Seit Mitte der 50er Jahre werden Atomkraftwerke gebaut und somit auch Abfälle produziert, die grosse Schwierigkeiten in der Handhabung und Lagerung mit sich bringen. Das grösste Problem liegt nicht in der Menge der Abfälle, sondern in der langanhaltenden schädlichen Strahlendosis die von den Abfällen abgegeben wird. Die momentan wissenschaftlich und wirtschaftlich vorherrschende Meinung ist, den Müll in geologischen Tiefenlagern zu deponieren. In der Vergangenheit wurden bereits unterschiedliche Gesteinsformationen als Endlagerstätten untersucht, getestet und auch eingesetzt. Viele haben sich jedoch als ungeeignet für die Deponierung atomaren Abfalls herausgestellt. Derzeit werden in Frankreich und der Schweiz Tonformationen als potenzielle Endlagerstandorte untersucht. Die geringe Durchlässigkeit und gleichermassen die über einen langen Zeitraum anhaltende Verschlusswirkung in Bezug auf Druck und Temperatur zeichnen eine Tonformation gegenüber Salz- oder Kristallinformationen aus. Zur Beurteilung eines potenziellen Endlagerstandorts werden geologische Erkundungen und Studien durchgeführt. Nach der ersten Erkundungsphase gilt es den Standort genauer zu untersuchen und das Gestein hinsichtlich seines Verhaltens während der Einlagerung zu verstehen. Um letztendlich eine Aussage über die Leistungsfähigkeit und Sicherheit eines potenziellen Endlagers machen zu können, sind auf Grundlage der zuvor gewonnenen Erkenntnisse umfangreiche numerische Simulationen nötig. Im Rahmen dieser Simulationen müssen unter anderem in der näheren Umgebung der Einlagerungsstollen hochaufgelöste Detailmodelle erstellt werden. Diese Modelle stellen die komplexen physikalischen Prozesse dar, die während der Einlagerung und nach dem Verschluss des Stollens ablaufen. Um möglichst viele Erkenntnisse über eventuelle Ereignisse oder Parameterunsicherheiten zu sammeln, müssen zusätzlich zu diesen Detailmodellen, deterministische und probabilistische Sicherheitsanalysen durchgeführt werden. Diese Arbeit wird bei der AF-Consult Switzerland AG im Rahmen eines durch die französische ANDRA (Agence nationale pour la gestion des déchets radioactifs – Französische nationale Agentur für die Entsorgung radioaktiver Abfälle) beauftragten Projekts durchgeführt. Dieses befasst sich mit der Optimierung und der effektiveren Umsetzung der Simulationen zur Berechnung der Radionuklidausbreitung. Durch die Projektvorgaben der ANDRA wird sich diese Arbeit an dem Endlagerkonzept der ANDRA orientieren. Die erarbeiteten numerischen Methoden sind aber gleichermassen auf andere Konzepte und Aufgabenstellungen anwendbar. Ein im Zusammenhang mit dieser Arbeit verfasster Konferenzbeitrag für das „TOUGH Symposium 2012“ wurde mit dem „Karsten Pruess Student Paper Award“ ausgezeichnet.