Oil-in-water and water-in-oil emulsions formation and demulsification

Sousa, Ana M.; Pereira, Maria João Veloso da Costa Ramos; Matos, Henrique A.

doi:10.1016/j.petrol.2021.110041

Cited by 88 publications

(24 citation statements)

References 199 publications

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“…Oil and water emulsions are often encountered in the petroleum industry, not only in oilfield exploitation but also during the transportation and refining processes . Especially in the later stage of oilfield development, crude oil is mostly recovered in the form of emulsion due to the increase of water content and the application of various enhanced oil recovery (EOR) techniques.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, coalescence may occur between two water droplets because of the above two potential mechanisms, i.e., dipole coalescence or migratory coalescence, thereby achieving the demulsification effect . It was found that the electric field, including AC, DC, pulsed-DC fields, and their combinations, is effective for the demulsification of W/O emulsion. − In addition, the electric field method also has the advantages of environmental friendliness and less energy consumption. ,, Therefore, electric field demulsification technology has been widely used in the petroleum industry. ,, …”

Section: Introductionmentioning

confidence: 99%

“…These natural surfactants will also promote the stability of the W/O emulsions by forming highly viscous or rigid interfacial films between oil and water. − As a result, the coalescence of water droplets is prevented. But on the other hand, some surfactants (e.g., nonionic surfactants) can destabilize the emulsions and so act as demulsifiers. ,,− It is suggested that the different surfactants may have different effects on the emulsions.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Study on the Demulsification Mechanism of Water-In-Oil Emulsion with SDS Surfactant under a DC Electric Field

Yuan

Zhang

et al. 2022

Langmuir

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Application of an electric field is an effective demulsification method for water-in-oil (W/O) emulsions. For the W/O emulsions stabilized by anionic surfactants, the microscopic demulsification mechanism is still not very clear. In this work, the coalescence behavior of two droplets stabilized by the anionic surfactant sodium dodecyl sulfate (SDS) in the oil phase under a DC electric field is investigated by molecular dynamics simulation. The effects of electric field strength and oil type on the electrocoalescence of two water droplets are mainly considered. The trajectory snapshots and center of mass of the two water droplets suggest that there is almost no migratory coalescence. The movement of sodium ions and SDS, which is a combined effect of the electric field force and the resistance from the oil phase, is crucial for the deformation and connection of two water droplets. The results of mean square displacement, radial distribution function, hydration number, and interaction energies of Na + -H 2 O and SDS-H 2 O indicate that the sodium ion has a stronger ability to carry water molecules for movement than SDS. The stronger electric field strength will result in more severe deformation and shorter coalescence time. Under the higher electric field strength, the two droplets will be elongated into a slender water ribbon. By applying a pulsed DC electric field with suitable amplitude, frequency, and duty ratio, it is possible to achieve full coalescence for the ionic surfactant-stabilized W/O emulsions. The oil phase also plays an important role for the deformation of droplets and the migration of emulsion components. For the different oil phases, a longer time or stronger electric field strength would be needed for the electrocoalescence of droplets in the oil phase with higher density and viscosity. Our results are expected to be helpful for practical application in the petroleum industry and chemical engineering.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Molecular Dynamics Study on the Demulsification Mechanism of Water-In-Oil Emulsion with SDS Surfactant under a DC Electric Field

Yuan

Zhang

et al. 2022

Langmuir

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“… 29 Ionic demulsifiers contain a positive or negative charge known as cationic or anionic demulsifiers, respectively. 30 Cationic demulsifiers are mainly quaternary ammonium salts that can reduce electrostatic repulsion among oil droplets, neutralize the negative charge on the surface of oil droplets, and thus enhance their coalescence. 31 Yonguep et al investigated the effect of two cationic demulsifiers (cetyl-trimethylammonium bromide and trimethyl-tetradecylammonium chloride) on the demulsification of O/W emulsions, and the results showed that above 80% demulsification efficiency was achieved with 10 h of settling.…”

Section: Introductionmentioning

confidence: 99%

“…Nonionic demulsifiers are mainly based on nonionic polyether and are not very effective at demulsifying O/W emulsion containing tiny emulsified oil droplets (≤2 μm). , They are also ineffective at demulsifying heavy crude oil emulsions, where only a 51.95% demulsification efficiency was achieved at high temperatures (e.g., 80 °C) . Ionic demulsifiers contain a positive or negative charge known as cationic or anionic demulsifiers, respectively . Cationic demulsifiers are mainly quaternary ammonium salts that can reduce electrostatic repulsion among oil droplets, neutralize the negative charge on the surface of oil droplets, and thus enhance their coalescence .…”

Section: Introductionmentioning

confidence: 99%

Investigation of Dioctyl Sodium Sulfosuccinate in Demulsifying Crude Oil-in-Water Emulsions

Hassanshahi

2022

ACS Omega

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This research investigated the performance of dioctyl sodium sulfosuccinate (DSS), a double-chain anionic surfactant, in breaking crude oil-in-water emulsions. The response surface methodology was used to consider the effect of the DSS concentration, oil concentration, and shaking time on demulsification efficiency and obtain optimum demulsification conditions. Further single-factor experiments were conducted to investigate the effects of salinity, crude oil conditions (fresh and weathered), and gravity separation settling time. The results showed that DSS efficiently demulsified stable emulsions under different oil concentrations (500–3000 mg/L) within 15 min shaking time. Increasing DSS concentration to 900 mg/L (critical micelle concentration) increased the demulsification efficiency to 99%. DSS not only improved the demulsification efficiency but also did not impede the demulsifier interfacial adsorption at the oil–water interface due to the presence of the double-chain structure. The low molecular weight enables the homogeneous distribution of DSS molecules in the emulsion, leading to a high demulsification efficiency within 15 min. Analysis of variance results indicated the importance of considering the interaction of oil concentration and shaking time in demulsification. DSS could reduce the total extractable petroleum hydrocarbons in the separated water to <10 mg/L without gravity separation and could achieve promising demulsification performance at high salinity (36 g/L) and various concentrations of fresh and weathered oil. The demulsification mechanism was explained by analyzing the microscopic images and the transmittance of the emulsion. DSS could be an efficient double-chain anionic surfactant in demulsifying stable oil-in-water emulsions.

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Preparation of cationic polyacrylate W/O crude oil emulsion demulsifier by free‐radical solution polymerization

Yuan

Wang

et al. 2023

J of Applied Polymer Sci

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The block polyether demulsifier prepared by ring-opening polymerization of ethylene oxide and propylene oxide under high temperature and high pressure is the most widely used demulsifier for water in crude oil emulsion. It has the high synthesis risk and cost. Therefore, the development of non-block polyether demulsifier has attracted more and more attention. In this article, a new type of demulsifier was sythesized by radical polymerization of acrylate and cationic monomer. It was found that the copolymer PMA-co-PDBC of methyl acrylate (MA) and benzyldimethyl [2-[(1-oxoallyl)oxy] ethyl] ammonium chloride (DBC) synthesized in the mixed solvent of dipropylene glycol methyl ether and water had a good performance. When dosage of PMA-co-PDBC was 200 mg/L, the dehydration rate of water in crude oil emulsion with 50% water content can reach 80% at 80 C within 4 h. Structural and interface properties analysis presented that PMA-co-PDBC had a microblock structure similar with block polyether and it can effectively reduce the strength of W/O interfacial film to realize the demulsification. Although the demulsification performance of PMA-co-PDBC was not better than block polyether, its preparation safety and cost are much better. The results of this article can provide a new option for the development of crude oil demulsifier.

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Oil-in-water and water-in-oil emulsions formation and demulsification

Cited by 88 publications

References 199 publications

Molecular Dynamics Study on the Demulsification Mechanism of Water-In-Oil Emulsion with SDS Surfactant under a DC Electric Field

Molecular Dynamics Study on the Demulsification Mechanism of Water-In-Oil Emulsion with SDS Surfactant under a DC Electric Field

Investigation of Dioctyl Sodium Sulfosuccinate in Demulsifying Crude Oil-in-Water Emulsions

Preparation of cationic polyacrylate W/O crude oil emulsion demulsifier by free‐radical solution polymerization

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