Project

Back to overview

Magnetic pore fabrics: Predicting pore geometry, permeability anisotropy and preferred flow directions based on magnetic anisotropy data

English title Magnetic pore fabrics: Predicting pore geometry, permeability anisotropy and preferred flow directions based on magnetic anisotropy data
Applicant Biedermann Andrea Regina
Number 176917
Funding scheme SNSF Professorships
Research institution Institut für Geologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Geophysics
Start/End 01.11.2018 - 31.10.2022
Approved amount 1'572'451.00
Show all

All Disciplines (2)

Discipline
Geophysics
Geology

Keywords (5)

permeability anisotropy; fluid flow; pore fabric; magnetic anisotropy; preferred flow direction

Lay Summary (German)

Lead
Um unser Trinkwasser sauber zu halten, Erdwärme zu nutzen, oder die Bildung von Erzlagerstättenzu verstehen, ist es wichtig zu wissen, wie sich Fluide (Flüssigkeiten, Gase) im Untergrundbewegen. Auf der Mikrometerskala müssen sich diese ihren Weg von Pore zu Pore suchen.Wenn längliche Poren eine bevorzugte Orientierung aufweisen, gibt es Richtungen, entlangdieser sich die Fluide schneller bewegen können, was zu bevorzugten Fliessrichtungenführt. Das Ziel dieses Projekts ist es, die Anwendung magnetischer Methoden voranzutreiben,um den Porenraum schneller und mit höherer Auflösung zu beschreiben als bisher. Diese neuenMethoden werden Anwendungen in den Geo-, Umwelt- und Materialwissenschaften finden.
Lay summary
Das Hauptziel dieses Projekts ist es den Porenraum in Gesteinen, insbesondere die Form und Orientierung der Poren und die daraus resultierenden bevorzugten Fliessrichtungen besser zu verstehen. Dazu werden wir eine Methode weiterentwickeln, die bisher vor allem dazu gebraucht wurde, die Orientierung von Mineralen im Gestein schnell und effizient zu beschreiben; magnetische Anisotropie, oder die Variation magnetischer Eigenschaften mit der Messrichtung. Die Idee hinter diesem Projekt ist, dass alle Poren im Gestein mit einer stark magnetischen Flüssigkeit, dem sogenannten Ferrofluid, gefüllt werden, und dann die magnetischen Eigenschaften dieser ferrofluid-gesättigten Probe gemessen werden. Wenn die magnetischen Eigenschaften von der Messrichtung abhängen, können Rückschlüsse über Porenform und deren bevorzugter Ausrichtung gezogen werden. Diese magnetische Methode ist effizienter und braucht weniger Speicherplatz als traditionelle Methoden der Porencharakterisierung. Ausserdem hat sie das Potential, dass kleinere Poren mit berücksichtigt werden können. Erste Resultate zeigen Potential, allerdings ist die Beziehung zwischen der Porengeometrie, -orientierung und -anordnung und magnetischen Resultaten noch nicht vollständig erforscht und verstanden. Deshalb werden wir in diesem Projekt die magnetische Methode mit anderen Methoden, die den Porenraum beschreiben, vergleichen, und Modelle entwickeln, die die Interpretation magnetischer Daten in Zukunft vereinfachen. Dadurch können Porenräume in künftigen Studien schneller beschrieben werden, was es Forschenden ermöglicht, mehr Proben zu analysieren und z.B. ein besseres Verständnis von lokalen Variationen der Fliesseigenschaften zu erhalten. Die Methode kann auf verschiedene Materialien angewendet werden, zum Beispiel auch in Material- und Umweltwissenschaften.
Direct link to Lay Summary Last update: 09.03.2018

Responsible applicant and co-applicants

Employees

Publications

Publication
Magnetic pore fabrics: the role of shape and distribution anisotropy in defining the magnetic anisotropy of ferrofluid-impregnated samples
Biedermann Andrea Regina, Magnetic pore fabrics: the role of shape and distribution anisotropy in defining the magnetic anisotropy of ferrofluid-impregnated samples, in Geochemistry, Geophysics, Geosystems.

Collaboration

Group / person Country
Types of collaboration
Anneleen Foubert, University of Fribourg Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Claudio Madonna, ETH Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Institute of Geological Sciences, Uni Bern (Diamond, Herwegh, Hermann) Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Kong Xiang-Zhao/Martin Saar, ETH Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Ann Hirt, ETH Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Josep Pares, CENIEH Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Swiss Geoscience Meeting Poster Characterization of 3D pore shape and distribution in sedimentary rocks with different porosity by X-ray microcomputed tomography 23.11.2019 Fribourg, Switzerland Biedermann Andrea Regina; Pugnetti Michele; Zhou Yi;
Swiss Geoscience Meeting Poster Anisotropy of magnetic susceptibility to investigate the pore fabric of rocks with various porosity using ferrofluid impregnation: First results and method improvements 23.11.2019 Fribourg, Switzerland Pugnetti Michele; Zhou Yi; Biedermann Andrea Regina; Bula Sandro;
Forum at the Institute of Geological Sciences, University of Bern Individual talk Quantitative comparison of 3D pore geometry by X-ray microcomputed tomography with magnetic pore fabrics in sedimentary rocks 28.10.2019 Bern, Switzerland Zhou Yi;
Forum at the Institute of Geological Sciences, University of Bern Individual talk Anisotropy of magnetic susceptibility to investigate the pore fabric of ferrofluid impregnated rocks 21.10.2019 Bern, Switzerland Pugnetti Michele;
EGU General Assembly Talk given at a conference Short course: Predicting anisotropic physical properties using single crystal and texture data; Session: Rock physics: upscaling thermo-hydro-mechanical rock properties from laboratory to natural systems 07.04.2019 Vienna, Austria Biedermann Andrea Regina;
Kolloquium at the Institute of Geological Sciences, University of Bern Individual talk Magnetic anisotropy: from single crystals to tectonic interpretations 04.03.2019 Bern, Switzerland Biedermann Andrea Regina;
AGU Fall Meeting Talk given at a conference Prediction of physical properties and anisotropy in rocks using mineral and microstructural data (Scientific Workshop) 09.12.2018 Washington DC, United States of America Biedermann Andrea Regina;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Magnetic fabrics: applications and challenges, Kolloquium at the Institute of Geophysics, ETH Zurich Talk 11.10.2019 Zurich, Switzerland Biedermann Andrea Regina;
Environmental magnetism: investigating formation, transportation and alteration processes with rock magnetic methods, Exogene Geology and Quaternary Global Change Seminar, University of Bern Talk 10.10.2019 Bern, Switzerland Biedermann Andrea Regina;
Fokus Forschung: Faszination Gesteinsmagnetismus Talk 25.04.2019 Bern, Universitätsbibliothek Münstergasse, Switzerland Biedermann Andrea Regina;
Das Magnetfeld - Die (un?)sichtbare Kraft, Schnuppertag für Maturandinnen Talk 21.03.2019 Bern, Institut für Geologie/Fakultät Naturwissenschaften, Switzerland Biedermann Andrea Regina;


Abstract

Pore fabric is defined as the shape and arrangement of pores and the ways they are connected, and is the primary control on rock properties such as permeability and transmissivity. Because pore fabric can be used as predictor for fluid flow directions, it has important applications to geothermal systems and to contaminant transport studies. Methods commonly used to directly assess pore fabrics include image analysis on thin sections, scanning electron microscopy (SEM) of surface pores, or X-ray computed tomography (XRCT). These direct methods have the advantage that they image and map pores; however, they are limited by spatial resolution, representativeness, pore alteration during sample preparation, time and the amount of data that needs to be stored and processed. Alternatively, pore fabrics can be characterized indirectly, using methods like permeability anisotropy, seismic anisotropy, or magnetic pore fabrics (MPF). Permeability anisotropy is the most direct predictor of preferred flow paths, but requires that the orientations of principal permeability axes are known prior to measurement. Seismic anisotropy is affected by both connected and unconnected pores, and may thus not relate reliably to flow properties. The magnetic anisotropy of ferrofluid-impregnated samples, i.e. MPF, has been proposed as a fast and efficient alternative to assess the average 3D structure of connected pores, that also captures a representative number of pores and pore sizes (down to 10 nm). This allows for big collections of samples to be analyzed, so that local or regional variations in pore fabric can be characterized. Initial studies show promising empirical relationships between preferred shape and orientation of pores and MPF, both in terms of principal directions and degree of anisotropy. However, the link between MPF and pore fabrics must be quantified before it can be used as a reliable tool. In particular, this project aims to determine how maximum susceptibility is oriented with respect to pore and pore throat orientations, and to quantify the relationship between the strength (degree) of MPF, pore fabric, and permeability anisotropy.The main focus of this interdisciplinary 4-year project is to develop a more systematic and quantitative understanding of MPF. Part A of the project investigates the variation of MPF with experimental parameters (fluid type, frequency), and seeks to identify contributions from different pores through analyzing both synthetic and natural samples. Part B compares MPF with permeability anisotropy and XRCT results. These results will be used to create models to predict MPF for given pore geometries, and to facilitate future interpretation of MPF measurements (Part C). Being interdisciplinary, this research provides a unique opportunity to train students in a variety of experimental methods. The project will establish a new research group in Rock Magnetism (2 PhD students, technician and principal investigator), and introduce magnetic methods as a complimentary method to tackle geological problems at the Institute of Geological Sciences, University of Bern. The institute offers a dynamic environment with exciting opportunities to apply these methods to ongoing geothermal or CO2-storage projects. Other collaborations within and outside the University of Bern are possible in the fields of Earth Science, Environmental Science, and Materials Research.
-