Optimized Droplet Sizing of Water-in-Crude Oil Emulsions Using Nuclear Magnetic Resonance

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    Abstract

    Water-in-crude oil emulsions are an increasing problem during production. Essential to any emulsion breaking method is an ability to accurately measure droplet size distributions; this is rendered extremely difficult given that the samples are both concentrated and opaque. Here, we systematically consider the use of a standard, low-field benchtop nuclear magnetic resonance (NMR) apparatus to accurately measure the droplet size distributions. Such measurements are challenging because the NMR signal from the oil phase erroneously contributes to the measured water droplet size distribution. Conventionally, the oil-phase signal is nulled-out based on differences in the NMR T1 relaxation parameter between water and oil. However, in the case of crude oil, the oil presents a broad T1 distribution, rendering this approach infeasible. On the basis of this oil T1 distribution, we present an optimization routine that adjusts various NMR measurement timing parameters [observation time (Δ) and inversion time (Tinv)] to effectively eliminate this erroneous crude oil contribution. An implementation of this optimization routine was validated against measurements performed using unambiguous chemical-shift selection of the water (droplet) signal, as would conventionally be provided by high-field superconducting NMR spectrometers. We finally demonstrate successful droplet sizing of a range of water-in-crude oil emulsions. © 2014 American Chemical Society.
    Original languageEnglish
    Pages (from-to)1756-1764
    JournalEnergy & Fuels
    Volume28
    Issue number3
    DOIs
    Publication statusPublished - 18 Feb 2014

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    Petroleum
    Emulsions
    Oils
    Crude oil
    Nuclear magnetic resonance
    Water
    Magnetic resonance spectrometers
    Magnetic resonance measurement
    Chemical shift

    Cite this

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    title = "Optimized Droplet Sizing of Water-in-Crude Oil Emulsions Using Nuclear Magnetic Resonance",
    abstract = "Water-in-crude oil emulsions are an increasing problem during production. Essential to any emulsion breaking method is an ability to accurately measure droplet size distributions; this is rendered extremely difficult given that the samples are both concentrated and opaque. Here, we systematically consider the use of a standard, low-field benchtop nuclear magnetic resonance (NMR) apparatus to accurately measure the droplet size distributions. Such measurements are challenging because the NMR signal from the oil phase erroneously contributes to the measured water droplet size distribution. Conventionally, the oil-phase signal is nulled-out based on differences in the NMR T1 relaxation parameter between water and oil. However, in the case of crude oil, the oil presents a broad T1 distribution, rendering this approach infeasible. On the basis of this oil T1 distribution, we present an optimization routine that adjusts various NMR measurement timing parameters [observation time (Δ) and inversion time (Tinv)] to effectively eliminate this erroneous crude oil contribution. An implementation of this optimization routine was validated against measurements performed using unambiguous chemical-shift selection of the water (droplet) signal, as would conventionally be provided by high-field superconducting NMR spectrometers. We finally demonstrate successful droplet sizing of a range of water-in-crude oil emulsions. {\circledC} 2014 American Chemical Society.",
    author = "Einar Fridjonsson and Brendan Graham and M. Akhfash and Eric May and Michael Johns",
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    journal = "Energy & Fuels",
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    Optimized Droplet Sizing of Water-in-Crude Oil Emulsions Using Nuclear Magnetic Resonance. / Fridjonsson, Einar; Graham, Brendan; Akhfash, M.; May, Eric; Johns, Michael.

    In: Energy & Fuels, Vol. 28, No. 3, 18.02.2014, p. 1756-1764.

    Research output: Contribution to journalArticle

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    AU - Graham, Brendan

    AU - Akhfash, M.

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    AB - Water-in-crude oil emulsions are an increasing problem during production. Essential to any emulsion breaking method is an ability to accurately measure droplet size distributions; this is rendered extremely difficult given that the samples are both concentrated and opaque. Here, we systematically consider the use of a standard, low-field benchtop nuclear magnetic resonance (NMR) apparatus to accurately measure the droplet size distributions. Such measurements are challenging because the NMR signal from the oil phase erroneously contributes to the measured water droplet size distribution. Conventionally, the oil-phase signal is nulled-out based on differences in the NMR T1 relaxation parameter between water and oil. However, in the case of crude oil, the oil presents a broad T1 distribution, rendering this approach infeasible. On the basis of this oil T1 distribution, we present an optimization routine that adjusts various NMR measurement timing parameters [observation time (Δ) and inversion time (Tinv)] to effectively eliminate this erroneous crude oil contribution. An implementation of this optimization routine was validated against measurements performed using unambiguous chemical-shift selection of the water (droplet) signal, as would conventionally be provided by high-field superconducting NMR spectrometers. We finally demonstrate successful droplet sizing of a range of water-in-crude oil emulsions. © 2014 American Chemical Society.

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