Quantifying the Effect of Salinity on Oilfield Water-in-Oil Emulsion Stability

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Abstract

The effect of salinity on water-in-oil emulsions was systematically studied using a combination of nuclear magnetic resonance (NMR) pulsed field gradient (PFG) measurements of emulsion droplet size distribution complemented by interfacial tension measurements using the pendant drop method. Long-term emulsion stability over periods of up to 5 days was found to increase with salinity; this was shown to be independent of whether a monovalent (NaCl) or divalent (CaCl2) salt was used. The methodology was applied to water-in-oil emulsions formulated with crude oil, paraffin oil, xylene, crude oil with reduced asphaltene content, and crude oil with reduced organic acid content as the continuous phase, respectively. In all cases, emulsion stability increased consistently with aqueous phase salinity, with no discernible difference between the continuous oil phases with respect to the extent of this stabilization. The enhanced stability could thus not be attributed to differences in density, interfacial tension, or dielectric permittivity. This leaves a potential increased surface accumulation of stabilizing surface-active species driven by increasing salinity as the most plausible explanation for the observations reported here.

Original languageEnglish
Pages (from-to)10042-10049
Number of pages8
JournalEnergy and Fuels
Volume32
Issue number9
DOIs
Publication statusPublished - 20 Sep 2018

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Emulsions
Oils
Petroleum
Water
Crude oil
Surface tension
Paraffin oils
Xylenes
Organic acids
Surface potential
Xylene
Permittivity
Stabilization
Salts
Nuclear magnetic resonance

Cite this

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title = "Quantifying the Effect of Salinity on Oilfield Water-in-Oil Emulsion Stability",
abstract = "The effect of salinity on water-in-oil emulsions was systematically studied using a combination of nuclear magnetic resonance (NMR) pulsed field gradient (PFG) measurements of emulsion droplet size distribution complemented by interfacial tension measurements using the pendant drop method. Long-term emulsion stability over periods of up to 5 days was found to increase with salinity; this was shown to be independent of whether a monovalent (NaCl) or divalent (CaCl2) salt was used. The methodology was applied to water-in-oil emulsions formulated with crude oil, paraffin oil, xylene, crude oil with reduced asphaltene content, and crude oil with reduced organic acid content as the continuous phase, respectively. In all cases, emulsion stability increased consistently with aqueous phase salinity, with no discernible difference between the continuous oil phases with respect to the extent of this stabilization. The enhanced stability could thus not be attributed to differences in density, interfacial tension, or dielectric permittivity. This leaves a potential increased surface accumulation of stabilizing surface-active species driven by increasing salinity as the most plausible explanation for the observations reported here.",
author = "Ling, {N. N.A.} and A. Haber and Graham, {B. F.} and Aman, {Z. M.} and May, {E. F.} and Fridjonsson, {E. O.} and Johns, {M. L.}",
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T1 - Quantifying the Effect of Salinity on Oilfield Water-in-Oil Emulsion Stability

AU - Ling, N. N.A.

AU - Haber, A.

AU - Graham, B. F.

AU - Aman, Z. M.

AU - May, E. F.

AU - Fridjonsson, E. O.

AU - Johns, M. L.

PY - 2018/9/20

Y1 - 2018/9/20

N2 - The effect of salinity on water-in-oil emulsions was systematically studied using a combination of nuclear magnetic resonance (NMR) pulsed field gradient (PFG) measurements of emulsion droplet size distribution complemented by interfacial tension measurements using the pendant drop method. Long-term emulsion stability over periods of up to 5 days was found to increase with salinity; this was shown to be independent of whether a monovalent (NaCl) or divalent (CaCl2) salt was used. The methodology was applied to water-in-oil emulsions formulated with crude oil, paraffin oil, xylene, crude oil with reduced asphaltene content, and crude oil with reduced organic acid content as the continuous phase, respectively. In all cases, emulsion stability increased consistently with aqueous phase salinity, with no discernible difference between the continuous oil phases with respect to the extent of this stabilization. The enhanced stability could thus not be attributed to differences in density, interfacial tension, or dielectric permittivity. This leaves a potential increased surface accumulation of stabilizing surface-active species driven by increasing salinity as the most plausible explanation for the observations reported here.

AB - The effect of salinity on water-in-oil emulsions was systematically studied using a combination of nuclear magnetic resonance (NMR) pulsed field gradient (PFG) measurements of emulsion droplet size distribution complemented by interfacial tension measurements using the pendant drop method. Long-term emulsion stability over periods of up to 5 days was found to increase with salinity; this was shown to be independent of whether a monovalent (NaCl) or divalent (CaCl2) salt was used. The methodology was applied to water-in-oil emulsions formulated with crude oil, paraffin oil, xylene, crude oil with reduced asphaltene content, and crude oil with reduced organic acid content as the continuous phase, respectively. In all cases, emulsion stability increased consistently with aqueous phase salinity, with no discernible difference between the continuous oil phases with respect to the extent of this stabilization. The enhanced stability could thus not be attributed to differences in density, interfacial tension, or dielectric permittivity. This leaves a potential increased surface accumulation of stabilizing surface-active species driven by increasing salinity as the most plausible explanation for the observations reported here.

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U2 - 10.1021/acs.energyfuels.8b02143

DO - 10.1021/acs.energyfuels.8b02143

M3 - Article

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EP - 10049

JO - Energy & Fuels

JF - Energy & Fuels

SN - 0887-0624

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ER -