NMR Measurements of Tortuosity in Partially Saturated Porous Media

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The tortuosity (τ), defined in the present context as the ratio of the free diffusion coefficient to the restricted diffusion coefficient of a contained fluid, is an important but difficult to measure characteristic of a porous medium, particularly when it is partially saturated with water. We develop and apply methodology, based on nuclear magnetic resonance (NMR) pulsed field gradient techniques, to measure τ for various sandstone rock cores as a function of residual water fraction. The NMR methodology requires the use of bipolar pulsed field gradient stimulated echo pulse sequences to avoid systematic errors due to magnetic susceptibility differences and D2O as a stationary immiscible water phase; this was selected as it provides no 1H NMR signal. Tortuosity of the free pore space was successfully measured using liquid ethane as a probe fluid for three different sandstones over the full accessible range of residual water saturation. Generally, the tortuosity was observed to increase with residual water (D2O) content; however, significant variations were observed between the different sandstones.

Original languageEnglish
Pages (from-to)271-288
Number of pages18
JournalTransport in Porous Media
Volume125
Issue number2
DOIs
Publication statusPublished - Nov 2018

Fingerprint

Magnetic resonance measurement
Porous materials
Sandstone
Nuclear magnetic resonance
Water
Ethane
Fluids
Systematic errors
Magnetic susceptibility
Water content
Rocks
Liquids

Cite this

@article{9858436961b3422a8b79136f02f293ac,
title = "NMR Measurements of Tortuosity in Partially Saturated Porous Media",
abstract = "The tortuosity (τ), defined in the present context as the ratio of the free diffusion coefficient to the restricted diffusion coefficient of a contained fluid, is an important but difficult to measure characteristic of a porous medium, particularly when it is partially saturated with water. We develop and apply methodology, based on nuclear magnetic resonance (NMR) pulsed field gradient techniques, to measure τ for various sandstone rock cores as a function of residual water fraction. The NMR methodology requires the use of bipolar pulsed field gradient stimulated echo pulse sequences to avoid systematic errors due to magnetic susceptibility differences and D2O as a stationary immiscible water phase; this was selected as it provides no 1H NMR signal. Tortuosity of the free pore space was successfully measured using liquid ethane as a probe fluid for three different sandstones over the full accessible range of residual water saturation. Generally, the tortuosity was observed to increase with residual water (D2O) content; however, significant variations were observed between the different sandstones.",
keywords = "Diffusion, PFGSTE, Tortuosity",
author = "Marco Zecca and Vogt, {Sarah J.} and Connolly, {Paul R.J.} and May, {Eric F.} and Johns, {Michael L.}",
year = "2018",
month = "11",
doi = "10.1007/s11242-018-1118-y",
language = "English",
volume = "125",
pages = "271--288",
journal = "Transport in Porous Media",
issn = "0169-3913",
publisher = "Springer",
number = "2",

}

NMR Measurements of Tortuosity in Partially Saturated Porous Media. / Zecca, Marco; Vogt, Sarah J.; Connolly, Paul R.J.; May, Eric F.; Johns, Michael L.

In: Transport in Porous Media, Vol. 125, No. 2, 11.2018, p. 271-288.

Research output: Contribution to journalArticle

TY - JOUR

T1 - NMR Measurements of Tortuosity in Partially Saturated Porous Media

AU - Zecca, Marco

AU - Vogt, Sarah J.

AU - Connolly, Paul R.J.

AU - May, Eric F.

AU - Johns, Michael L.

PY - 2018/11

Y1 - 2018/11

N2 - The tortuosity (τ), defined in the present context as the ratio of the free diffusion coefficient to the restricted diffusion coefficient of a contained fluid, is an important but difficult to measure characteristic of a porous medium, particularly when it is partially saturated with water. We develop and apply methodology, based on nuclear magnetic resonance (NMR) pulsed field gradient techniques, to measure τ for various sandstone rock cores as a function of residual water fraction. The NMR methodology requires the use of bipolar pulsed field gradient stimulated echo pulse sequences to avoid systematic errors due to magnetic susceptibility differences and D2O as a stationary immiscible water phase; this was selected as it provides no 1H NMR signal. Tortuosity of the free pore space was successfully measured using liquid ethane as a probe fluid for three different sandstones over the full accessible range of residual water saturation. Generally, the tortuosity was observed to increase with residual water (D2O) content; however, significant variations were observed between the different sandstones.

AB - The tortuosity (τ), defined in the present context as the ratio of the free diffusion coefficient to the restricted diffusion coefficient of a contained fluid, is an important but difficult to measure characteristic of a porous medium, particularly when it is partially saturated with water. We develop and apply methodology, based on nuclear magnetic resonance (NMR) pulsed field gradient techniques, to measure τ for various sandstone rock cores as a function of residual water fraction. The NMR methodology requires the use of bipolar pulsed field gradient stimulated echo pulse sequences to avoid systematic errors due to magnetic susceptibility differences and D2O as a stationary immiscible water phase; this was selected as it provides no 1H NMR signal. Tortuosity of the free pore space was successfully measured using liquid ethane as a probe fluid for three different sandstones over the full accessible range of residual water saturation. Generally, the tortuosity was observed to increase with residual water (D2O) content; however, significant variations were observed between the different sandstones.

KW - Diffusion

KW - PFGSTE

KW - Tortuosity

UR - http://www.scopus.com/inward/record.url?scp=85049940525&partnerID=8YFLogxK

U2 - 10.1007/s11242-018-1118-y

DO - 10.1007/s11242-018-1118-y

M3 - Article

VL - 125

SP - 271

EP - 288

JO - Transport in Porous Media

JF - Transport in Porous Media

SN - 0169-3913

IS - 2

ER -