Formation and stability of emulsions produced by dilution of emulsifiable concentrates. Part III. The coalescence of oil droplets at a planar oil—water interface

Summary The conventional experimental techniques used for performance evaluation of enhanced oil recovery (EOR) chemicals, such as polymers and surfactants, have been mostly limited to bulk viscosity, phase behavior/interfacial tension (IFT), and thermal stability measurements. Furthermore, fundamental studies exploring the different microscale interactions instigated by the EOR chemicals at the crude oil/water interface are scanty. The objective of this experimental study is to fill this existing knowledge gap and deliver an important understanding on underlying interfacial sciences and their potential implications for oil recovery in chemical EOR. Different microscale interactions of EOR chemicals, at crude oil/water interface, were studied by using a suite of experimental techniques, including an interfacial shear rheometer, Langmuir trough, and coalescence time measurement apparatus at both ambient (23°C) and elevated (70°C) temperatures. The reservoir crude oil and high-salinity injection water (57,000 ppm total dissolved solids) were used. Two chemicals, an amphoteric surfactant (at 1,000 ppm) and a sulfonated polyacrylamide polymer (at 500 and 700 ppm) were chosen because they are tolerant to high-salinity and high-temperature conditions. Interfacial viscous and elastic moduli (viscoelasticity), interface pressures, interface compression energies, and coalescence time between crude oil droplets are the major experimental data measured. Interfacial shear rheology results showed that surfactant favorably reduced the viscoelasticity of crude oil/water interface by decreasing the elastic and viscous modulus and increasing the phase angle to soften the interfacial film. Polymers in brine either alone or together with surfactant increased the viscous and elastic modulus and decreased the phase angle at the oil/water interface, thereby contributing to interfacial film rigidity. Interfacial pressures with polymers remained almost in the same order of magnitude as the high-salinity brine. In contrast, a significant reduction in interfacial pressures with surfactant was observed. The interface compression energies indicated the same trend and were reduced by approximately two orders of magnitude when surfactant was added to the brine. The surfactant was also able to retain similar interface behavior under compression even in the presence of polymers. The coalescence times between crude oil droplets were increased by polymers, while they were substantially decreased by the surfactant. These consistent findings from different experimental techniques demonstrated the adverse interactions of polymers at the crude oil/water interface to result in more rigid films, while confirming the high efficiency of the surfactant to soften the interfacial film, promote the oil droplets coalescence, and mobilize substantial amounts of residual oil in chemical EOR. This experimental study, for the first time, characterized the microscale interactions of surfactant-polymer chemicals at the crude oil/water interface. The applicability of several interfacial experimental techniques has been demonstrated to successfully understand underlying interfacial sciences and oil mobilization mechanisms in chemical EOR. These techniques and methods can provide potential means to efficiently screen and optimize EOR chemical formulations for better oil recovery in both sandstone and carbonate reservoirs.

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Reversible adsorption of proteins at the oil/water interface I. Preferential adsorption of proteins at charged oil/water interfaces

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1946.0006 ◽

1946 ◽

Vol 133 (870) ◽

pp. 121-121

Keyword(s):

Sodium Chloride ◽

Isoelectric Point ◽

Interfacial Area ◽

Ammonium Bromide ◽

Water Interface ◽

Oil Droplets ◽

Water Emulsion ◽

Oil In Water ◽

Alkaline Side ◽

Oil Water

The behaviour of positively and negatively charged oil-in-water emulsions, stabilized with hexadecyl trimethyl ammonium bromide and sodium hexadecyl sulphate respectively in the presence of protein solutions has been studied. Under certain conditions proteins will adsorb to a charged oil/water interface. When finely dispersed oil-in-water emulsion was used to provide this oil/water interface, adsorption of protein resulted in flocculation of the oil droplets. Flocculation of emulsion on the addition of protein is pH conditioned and occurred on the acid side of the isoelectric point of the protein with negatively charged and on the alkaline side with positively charged oil globules. No flocculation occurred on the alkaline side of the isoelectric point with a negative emulsion or the acid side with a positive emulsion. The amount of protein required to cause maximum clarification of the subnatant fluid corresponded with that needed to give a firmly gelled protein monolayer at the interface, namely, 2∙5 mg. of protein/sq. m. of interfacial area. With that amount of protein the flocculated oil globules remained discrete and no coalescence or liberation of free oil occurred. If only 1 mg. of protein/sq. m. of interfacial area was added, flocculation was followed by rapid coalescence of oil globules and liberation of free oil. If smaller amounts still were used, no visible change in the dispersion of the oil droplets could be seen macroscopically. With greater amounts than 2∙5 mg. /sq. m. of interfacial area, up to ten times the monolayer concentration was adsorbed to the interface. Sodium chloride affected the flocculation range, and instead of the clear-cut change-over between the positive and negative interfaces at the isoelectric point of the protein, overlapping occurred. 5% sodium chloride shifted the flocculation point about 1 unit of pH . The addition of sodium chloride also altered the point of maximum clarification. Thus with haemoglobin the maximum clarification point was shifted from 2∙5 to 1∙7 mg. /sq. m. of interfacial area by the addition of 1% sodium chloride. The adsorption of protein on to charged oil/water interfaces was reversible. This was best demonstrated with haemoglobin. Thus, haemoglobin was adsorbed at pH 5∙0 to a negative emulsion—the red floccules were washed and transferred to a buffer at pH 10. The haemoglobin was released and the emulsion was redispersed. The effect of adsorption and desorption on the structure of the protein molecule has been studied with haemoglobin. By solubility and colour tests it was shown that the haemoglobin molecule was changed to parahaematin by adsorption and subsequent desorption from a charged oil /water interface. Molecular weight and shape determinations were carried out on the desorbed protein. Two proteins have been separated by this adsorption mechanism. This was demonstrated on a mixture of album in and haemoglobin. Some applications of the flocculation technique are indicated and the significance of the phenomena described are discussed.

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Stabilisation of Emulsified Agarwood Oil in an Aqueous System Using Non-Ionic Surfactant

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.797.186 ◽

2019 ◽

Vol 797 ◽

pp. 186-195

Author(s):

Boon Yih Tien ◽

Mohd Nazli Naim ◽

Rabitah Zakaria ◽

Noor Fitrah Abu Bakar ◽

Noraini Ahmad ◽

...

Keyword(s):

Zeta Potential ◽

Droplet Size ◽

Ostwald Ripening ◽

Alkaline Condition ◽

Ionic Surfactant ◽

Water Interface ◽

Oil Droplets ◽

Emulsified Oil ◽

Oil Water ◽

Agarwood Oil

Owing to the annually increasing market value of pure agarwood oil, the extracted agarwood oil from Aquilaria malaccensis was emulsified in an aqueous solution using non-ionic surfactant (Tween 80). The surfactant concentration of 0.0167% was determined as the critical micelle concentration (CMC) with an interfacial tension value of 0.014 mNm-1. The adsorption of surfactant at the oil/water interface at the CMC value, however, reduced the zeta potential of the emulsified oil from –45 to –43 mV, and increased its size from 85 to 89 nm. Outside of the CMC value, the emulsified oil droplets tended to coalesce, owing to insufficient coverage of the surfactant at oil/water interface and Ostwald ripening. The droplet size distribution and zeta potential value of the emulsified oil droplets produced at the CMC were the most stable over a month of storage. No significant changes in the emulsified droplet size occurred when the pH conditions varied from pH 3 to 10. The emulsified droplets images obtained from transmission electron microscopy analysis showed a reduction in the layer thickness of the surfactant from 30 to 10 nm in acidic condition and 30 to 19 nm in alkaline condition. The agarwood oil emulsification at CMC value enhance the stability of chemically unstable compounds from degradation.

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Reversible adsorption of proteins at the oil/water interface I. Preferential adsorption of proteins at charged oil/water interfaces

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1943.0042 ◽

1945 ◽

Vol 184 (996) ◽

pp. 102-115 ◽

Cited By ~ 6

Keyword(s):

Sodium Chloride ◽

Isoelectric Point ◽

Interfacial Area ◽

Ammonium Bromide ◽

Water Interface ◽

Oil Droplets ◽

Water Emulsion ◽

Oil In Water ◽

Alkaline Side ◽

Oil Water

The behaviour of positively and negatively charged oil-in-water emulsions, stabilized with hexadecyl trimethyl ammonium bromide and sodium hexadecyl sulphate respectively in the presence of protein solutions has been studied. Under certain conditions proteins will adsorb to a charged oil/water interface. When finely dispersed oil-in-water emulsion was used to provide this oil/water interface, adsorption of protein resulted in flocculation of the oil droplets. Flocculation of emulsion on the addition of protein is pH conditioned and occurred on the acid side of the isoelectric point of the protein with negatively charged and on the alkaline side with positively charged oil globules. No flocculation occurred on the alkaline side of the isoelectric point with a negative emulsion or the acid side with a positive emulsion. The amount of protein required to cause maximum clarification of the subnatant fluid corresponded with that needed to give a firmly gelled protein monolayer at the interface, namely, 2·5 mg. of protein/sq.m, of interfacial area. With that amount of protein the flocculated oil globules remained discrete and no coalescence or liberation of free oil occurred. If only 1 mg. of protein/sq.m, of interfacial area was added, flocculation was followed by rapid coalescence of oil globules and liberation of free oil. If smaller amounts still were used, no visible change in the dispersion of the oil droplets could be seen macroscopically. With greater amounts than 2·5 mg./sq.m, of interfacial area, up to ten times the monolayer concentration was adsorbed to the interface. Sodium chloride affected the flocculation range, and instead of the clear-cut change-over between the positive and negative interfaces at the isoelectric point of the protein, overlapping occurred. 5 % sodium chloride shifted the flocculation point about 1 unit of pH. The addition of sodium chloride also altered the point of maximum clarification. Thus with haemoglobin the maximum clarification point was shifted from 2·5 to 1·7 mg./sq.m. of interfacial area by the addition of 1 % sodium chloride. The adsorption of protein on to charged oil/water interfaces was reversible. This was best demonstrated with haemoglobin. Thus, haemoglobin was adsorbed at pH 5·0 to a negative emulsion— the red floccules were washed and transferred to a buffer at pH 10. The haemoglobin was released and the emulsion was redispersed. The effect of adsorption and desorption on the structure of the protein molecule has been studied with haemoglobin. By solubility and colour tests it was shown that the haemoglobin molecule was changed to parahaematin by adsorption and subsequent desorption from a charged oil/water interface. Molecular weight and shape determinations were carried out on the desorbed protein. Two proteins have been separated by this adsorption mechanism. This was demonstrated on a mixture of albumin and haemoglobin. Some applications of the flocculation technique are indicated and the significance of the phenomena described are discussed.

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Persistent thin water films encapsulate oil droplets crossing an oil-water interface

Chemical Engineering Journal ◽

10.1016/j.cej.2020.124075 ◽

2020 ◽

Vol 387 ◽

pp. 124075

Author(s):

Omri Ram ◽

Joseph Katz

Keyword(s):

Water Interface ◽

Oil Droplets ◽

Water Films ◽

Oil Water

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Bacterial motility enhances adhesion to oil droplets

Soft Matter ◽

10.1039/d0sm00944j ◽

2020 ◽

Vol 16 (35) ◽

pp. 8237-8244

Author(s):

Narendra K. Dewangan ◽

Jacinta C. Conrad

Keyword(s):

Marine Bacteria ◽

Bacterial Motility ◽

Water Interface ◽

Oil Droplets ◽

Oil Water

Adhesion of marine bacteria onto the oil–water interface is enhanced by motility.

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Water Ion Interactions at Crude-Oil/Water Interface and Their Implications for Smart Waterflooding in Carbonates

SPE Journal ◽

10.2118/183894-pa ◽

2018 ◽

Vol 23 (05) ◽

pp. 1817-1832 ◽

Cited By ~ 8

Author(s):

Subhash C. Ayirala ◽

Ali A. Al-Yousef ◽

Zuoli Li ◽

Zhenghe Xu

Keyword(s):

Crude Oil ◽

Oil Recovery ◽

Measurement Techniques ◽

Fluid Interfaces ◽

Water Interface ◽

Oil Droplets ◽

Coalescence Time ◽

Ion Interactions ◽

Phase Connectivity ◽

Oil Water

Summary Smart waterflooding (SWF) through tailoring of injection-water salinity and ionic composition is receiving favorable attention in the industry for both improved and enhanced oil recovery (EOR) in carbonate reservoirs. Surface/intermolecular forces, thin-film dynamics, and capillary/adhesion forces at rock/fluid interfaces govern crude-oil liberation from pores. On the other hand, stability and rigidity of oil/water interfaces control the destabilization of interfacial film to promote coalescence between released oil droplets and to improve the oil-phase connectivity. As a result, the dynamics of oil recovery in smart waterflood is caused by the combined effect of favorable interactions occurring at both oil/brine and oil/brine/rock interfaces across the thin film. Most of the laboratory studies reported so far have been focused on only studying the interactions at rock/fluid interfaces. However, the other important aspect of characterizing water ion interactions at the crude oil/water interface and their impact on film stability and oil-droplet coalescence remains largely unexplored. A detailed experimental investigation was conducted to understand the effects of different water ions at the crude-oil/water interface by using several instruments such as Langmuir trough, interfacial shear rheometer, Attension tensiometer, and coalescence time-measurement apparatus. The reservoir crude oil and four different water recipes with varying salinities and individual ion concentrations were used. Interfacial tension (IFT), interface pressures, compression energy, interfacial viscous and elastic moduli, oil-droplet crumpling ratio, and coalescence time between crude-oil droplets are the major experimental data measured. The IFTs are found to be the largest for deionized (DI) water, followed by the 10-times-reduced-salinity seawater and 10-times-reduced-salinity seawater enriched with sulfates. Interfacial pressures gradually increased with compressing surface area for all the brines and DI water. The compression energy (integration of interfacial pressure over the surface-area change) is the highest for DI water, followed by the lower-salinity brine containing sulfate ions, indicating rigid interfaces. The transition times of interfacial layer to become elastic-dominant from viscous-dominant structures are found to be much shorter for brines enriched with sulfates, once again confirming the rigidity of interface. The crumpling ratios (oil drop wrinkles when contracted) are also higher with the two recipes of DI water and sulfates-only brine to indicate the same trend and to confirm elastic rigid skin at the interface. The coalescence time between oil droplets was the least in brines containing sufficient amounts of magnesium and calcium ions, while the highest in DI water and sulfate-rich brine, respectively. These results, therefore, showed a good correlation of coalescence times with the rigidity of oil/water interface, as interpreted from different measurement techniques. This study, thereby, integrates consistent results obtained from different measurement techniques at the crude-oil/water interface to demonstrate the importance of both salinity and certain ions, such as magnesium and calcium, on crude-oil-droplets coalescence, and to improve oil-phase connectivity in smart waterflood.

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Porous materials from cellulose nanocrystal and mxene surfactants at the oil/water interface

10.1021/scimeetings.0c07366 ◽

2020 ◽

Author(s):

Bingqing qian ◽

Haiqiao Wang ◽

Dong Wang ◽

Hao-Bin Zhang ◽

Jessica Wu ◽

...

Keyword(s):

Porous Materials ◽

Cellulose Nanocrystal ◽

Water Interface ◽

Oil Water

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Polarizability and nonpolarizability of oil-water interfaces with relevance to a.c. impendance measurements

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19910112 ◽

1991 ◽

Vol 56 (1) ◽

pp. 112-129 ◽

Cited By ~ 14

Author(s):

Takashi Kakiuchi ◽

Mitsugi Senda

Keyword(s):

Charge Transfer ◽

Numerical Calculation ◽

Supporting Electrolyte ◽

Water Interface ◽

Migration Effect ◽

Ac Current ◽

Stationary Interface ◽

Oil Water ◽

Anion Transfer

We have estimated the degree of polarizability of a polarized oil-water interface used as a working interface and that of the nonpolarizability of a nonpolarized interface used as a reference oil-water interface from the numerical calculation of dc and ac current vs potential behavior at both interfaces. Theoretical equations of dc and ac currents for simultaneous cation and anion transfer of supporting electrolytes have been derived for the planar stationary interface for reversible and quasi-reversible cases. In the derivation, the migration effect and the coupling of the cation and anion transfer have been incorporated. The transfer of ions constituting a supporting electrolyte contributes to the total admittance of the interface even in the region where the interface may be considered as polarized in dc sense, as pointed out first by Samec et al. (J. Electroanal. Chem. 126, 121 (1981)). Moreover, the reference oil-water interface is not ideally reversible, so that the contribution from this interface to the measured admittance cannot be negligible, unless the area of the reference oil-water interface is much larger than that of the working oil-water interface. The effect of non-ideality of the reference oil-water interface on the determination of double layer capacitances and kinetic parameters of charge transfer at the working oil-water interface has been estimated.

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