Towards a better understanding of electrical relaxation
- Other than commonly assumed the relaxation times observed in the electrical low-frequency range (1 mHz – 40 kHz) of natural porous media like sandstones and tuff stones cannot be directly related to the dominant (modal) pore throat sizes, measured (e.g.) with mercury intrusion porosimetry (MIP). Working with a great variety of sandstones from very different origins and featuring great variations in textural and chemical compositions as well as in geometrical pore space properties, it was observed that particularly samples with narrow pore throats were characterized by long (low-frequency) relaxations. These, however, can (following the current theories) be rather explained by long “characteristic length scales” in these media or low diffusion coefficients along the electrical double layer. However, there is no straightforward way (or single approved method) of getting reliable numbers for properties such as the lengths of pore throats, the diameter and length of the wide pores andOther than commonly assumed the relaxation times observed in the electrical low-frequency range (1 mHz – 40 kHz) of natural porous media like sandstones and tuff stones cannot be directly related to the dominant (modal) pore throat sizes, measured (e.g.) with mercury intrusion porosimetry (MIP). Working with a great variety of sandstones from very different origins and featuring great variations in textural and chemical compositions as well as in geometrical pore space properties, it was observed that particularly samples with narrow pore throats were characterized by long (low-frequency) relaxations. These, however, can (following the current theories) be rather explained by long “characteristic length scales” in these media or low diffusion coefficients along the electrical double layer. However, there is no straightforward way (or single approved method) of getting reliable numbers for properties such as the lengths of pore throats, the diameter and length of the wide pores and their respective distributions. Consequently we follow a multi-methodical approach and combine the benefits of MIP, micro-computed tomography (μ-CT) and nuclear magnetic resonance (NMR) to achieve much deeper insight due to the different resolutions and sensitivities to either pore constrictions (throats) or wide pores. This helps us to understand, whether the observed electrical relaxation phenomena actually depend on geometric length scales or rather on other properties such as chemical composition, clay content, clay type or cation exchange capacity. In this paper, we showcase selected results of a systematic study of a total of 16 sandstones and three tuffs. Findings and the particular advantage of the used method combination are discussed and shown in detail for a representative sample selection.…
Autor*innen: | Sabine KruschwitzORCiD, M. Halisch, Carsten PrinzORCiD, Andreas Weller, M. Müller-Petke, R. Dlugosch |
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Dokumenttyp: | Beitrag zu einem Tagungsband |
Veröffentlichungsform: | Graue Literatur |
Sprache: | Englisch |
Titel des übergeordneten Werkes (Englisch): | Proceedings of the Annual Symposium of the Society of Core Analysts (SCA) |
Jahr der Erstveröffentlichung: | 2017 |
Jahrgang/Band: | SCA2017-080 |
Erste Seite: | 1 |
Letzte Seite: | 9 |
DDC-Klassifikation: | Naturwissenschaften und Mathematik / Chemie / Analytische Chemie |
Freie Schlagwörter: | Complex resistivity; Electrical relaxation; Mercury intrusion porosimetry; Nuclear magnetic resonance; Pore size distribution; Sandstone; Spectral induced polarization |
Veranstaltung: | Annual Symposium of the Society of Core Analysts (SCA) |
Veranstaltungsort: | Vienna, Austria |
Beginndatum der Veranstaltung: | 28.08.2017 |
Enddatum der Veranstaltung: | 01.09.2017 |
Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |
Datum der Freischaltung: | 21.11.2017 |
Referierte Publikation: | Nein |