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Temperature-Dependent Oxygen Effect on NMR D-[Formula: see text] Relaxation-Diffusion Correlation of n-Alkanes

Nuclear magnetic resonance (NMR) diffusion-relaxation correlation experiments (D-[Formula: see text] ) are widely used for the petrophysical characterisation of rocks saturated with petroleum fluids both in situ and for laboratory analyses. The encoding for both diffusion and relaxation offers incre...

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Autores principales: Shikhov, Igor, Arns, Christoph H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Vienna 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5099375/
https://www.ncbi.nlm.nih.gov/pubmed/27881902
http://dx.doi.org/10.1007/s00723-016-0830-4
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author Shikhov, Igor
Arns, Christoph H.
author_facet Shikhov, Igor
Arns, Christoph H.
author_sort Shikhov, Igor
collection PubMed
description Nuclear magnetic resonance (NMR) diffusion-relaxation correlation experiments (D-[Formula: see text] ) are widely used for the petrophysical characterisation of rocks saturated with petroleum fluids both in situ and for laboratory analyses. The encoding for both diffusion and relaxation offers increased fluid typing contrast by discriminating fluids based on their self-diffusion coefficients, while relaxation times provide information about the interaction of solid and fluid phases and associated confinement geometry (if NMR responses of pure fluids at particular temperature and pressure are known). Petrophysical interpretation of D-[Formula: see text] correlation maps is typically assisted by the “standard alkane line”—a relaxation-diffusion correlation valid for pure normal alkanes and their mixtures in the absence of restrictions to diffusing molecules and effects of internal gradients. This correlation assumes fluids are free from paramagnetic impurities. In situations where fluid samples cannot be maintained at air-free state the diffusion-relaxation response of fluids shift towards shorter relaxation times due to oxygen paramagnetic relaxation enhancement. Interpretation of such a response using the “standard alkane line” would be erroneous and is further complicated by the temperature-dependence of oxygen solubility for each component of the alkane mixture. We propose a diffusion-relaxation correlation suitable for interpretation of low-field NMR D-[Formula: see text] responses of normal alkanes and their mixtures saturating rocks over a broad temperature range, in equilibrium with atmospheric air. We review and where necessary revise existing viscosity-relaxation correlations. Findings are applied to diffusion-relaxation dependencies taking into account the temperature dependence of oxygen solubility and solvent vapour pressure. The effect is demonstrated on a partially saturated carbonate rock.
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spelling pubmed-50993752016-11-21 Temperature-Dependent Oxygen Effect on NMR D-[Formula: see text] Relaxation-Diffusion Correlation of n-Alkanes Shikhov, Igor Arns, Christoph H. Appl Magn Reson Original Paper Nuclear magnetic resonance (NMR) diffusion-relaxation correlation experiments (D-[Formula: see text] ) are widely used for the petrophysical characterisation of rocks saturated with petroleum fluids both in situ and for laboratory analyses. The encoding for both diffusion and relaxation offers increased fluid typing contrast by discriminating fluids based on their self-diffusion coefficients, while relaxation times provide information about the interaction of solid and fluid phases and associated confinement geometry (if NMR responses of pure fluids at particular temperature and pressure are known). Petrophysical interpretation of D-[Formula: see text] correlation maps is typically assisted by the “standard alkane line”—a relaxation-diffusion correlation valid for pure normal alkanes and their mixtures in the absence of restrictions to diffusing molecules and effects of internal gradients. This correlation assumes fluids are free from paramagnetic impurities. In situations where fluid samples cannot be maintained at air-free state the diffusion-relaxation response of fluids shift towards shorter relaxation times due to oxygen paramagnetic relaxation enhancement. Interpretation of such a response using the “standard alkane line” would be erroneous and is further complicated by the temperature-dependence of oxygen solubility for each component of the alkane mixture. We propose a diffusion-relaxation correlation suitable for interpretation of low-field NMR D-[Formula: see text] responses of normal alkanes and their mixtures saturating rocks over a broad temperature range, in equilibrium with atmospheric air. We review and where necessary revise existing viscosity-relaxation correlations. Findings are applied to diffusion-relaxation dependencies taking into account the temperature dependence of oxygen solubility and solvent vapour pressure. The effect is demonstrated on a partially saturated carbonate rock. Springer Vienna 2016-09-19 2016 /pmc/articles/PMC5099375/ /pubmed/27881902 http://dx.doi.org/10.1007/s00723-016-0830-4 Text en © The Author(s) 2016 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
spellingShingle Original Paper
Shikhov, Igor
Arns, Christoph H.
Temperature-Dependent Oxygen Effect on NMR D-[Formula: see text] Relaxation-Diffusion Correlation of n-Alkanes
title Temperature-Dependent Oxygen Effect on NMR D-[Formula: see text] Relaxation-Diffusion Correlation of n-Alkanes
title_full Temperature-Dependent Oxygen Effect on NMR D-[Formula: see text] Relaxation-Diffusion Correlation of n-Alkanes
title_fullStr Temperature-Dependent Oxygen Effect on NMR D-[Formula: see text] Relaxation-Diffusion Correlation of n-Alkanes
title_full_unstemmed Temperature-Dependent Oxygen Effect on NMR D-[Formula: see text] Relaxation-Diffusion Correlation of n-Alkanes
title_short Temperature-Dependent Oxygen Effect on NMR D-[Formula: see text] Relaxation-Diffusion Correlation of n-Alkanes
title_sort temperature-dependent oxygen effect on nmr d-[formula: see text] relaxation-diffusion correlation of n-alkanes
topic Original Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5099375/
https://www.ncbi.nlm.nih.gov/pubmed/27881902
http://dx.doi.org/10.1007/s00723-016-0830-4
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