Preliminary Material

Sørbø, Marie Nedregotten

doi:10.1163/9789004337176_001

Cited by 2 publications

(3 citation statements)

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“…However, the exact compositions of crude oil, which consists of thousands of different components, are hardly accessible. − Furthermore, the crude oils used in these experiments also have different compositions from various sources. The probable reasons for the controversies in the synthetic oil–brine systems are diverse experimental conditions and purity of the samples, while for crude oil–brine systems, the most probable reason might be the different oil compositions, especially the polar components, which serve as surface-active species and have significant influences on interfacial properties. ,, Therefore, the explicit understanding of the effect of salinity on the oil–brine interfacial phenomena and IFT with different oil components is still unclear. Furthermore, grasping the corresponding underlying mechanisms still remains a daunting challenge for experiments. ,,− …”

Section: Introductionmentioning

confidence: 99%

“…The polar components are represented by N-bearing compounds (pyridine and quinoline), S-bearing compounds (thiophene and benzothiophene), and O-bearing compounds (phenol and decanoic acid), respectively, which are used to explicitly study their effects in oil–brine systems. Although the polar components used in this work are commonly present in oils, their effects on oil–brine interfacial properties are rarely studied. ,, However, it should be noted that they cannot stand for all polar components of crude oils. We simulate under a typical reservoir condition (353 K and 200 bar) and investigate the effects of salinity as well as various polar components on the oil–brine interfacial properties, after carefully calibrating the force fields and system size.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Salinity and N-, S-, and O-Bearing Polar Components on Light Oil–Brine Interfacial Properties from Molecular Perspectives

Nan

Wen

et al. 2019

J. Phys. Chem. C

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Oil–brine interfaces play an important role in oil recovery and oil–brine separation, in which the effects of salinity on interfacial tension (IFT) have been much of debate in the past in experiments and modeling studies owing to complex oil compositions. In this work, we use molecular dynamics (MD) simulations to study the oil–brine interfacial properties by designing seven systems containing different oil compositions (decane with/without polar compounds) and the salinity in brine of up to ∼14 wt %. We carefully investigate the salinity and polar component effects by analyzing IFTs, density profiles, orientation parameters, hydrogen bond densities, and charge density profiles. The results indicate that O-bearing compounds (phenol and decanoic acid) can significantly reduce the oil–brine IFT and exhibit the highest Gibbs surface excess relative to water, while the others, including N-bearing compounds (pyridine and quinoline) and S-bearing compounds (thiophene and benzothiophene), only slightly decrease the oil–brine IFTs and show a relatively small Gibbs surface excess. Increasing salinity can slightly increase the oil–brine IFT except in the system containing phenol, which shows a decrease. Phenol and decanoic acid incline to be perpendicular to the interface and generate numerous hydrogen bonds with water in the interfacial region, while others prefer to be parallel to the interface with much fewer hydrogen bonds with water. On the other hand, salinity has an insignificant effect on the orientation of polar molecules and hydrogen bond density in the interfacial region. The charges at the interfaces on the brine and oil sides are negative and positive, respectively, and the polar compounds disturb the arrangement of water molecules in the interfacial regions, while the addition of salt ions result in the higher peak values of charges in terms of water and system. Our study should provide new insights into the oil–brine interfacial issues and clarify some unsettled disputes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Salinity and N-, S-, and O-Bearing Polar Components on Light Oil–Brine Interfacial Properties from Molecular Perspectives

Nan

Wen

et al. 2019

J. Phys. Chem. C

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“…Furthermore, most studies in the literature use a simple hydrocarbon to represent the crude oil phase (e.g., octane, decane, or dodecane) and ignore the crude oil’s structural complexity. , The many controversies in the literature on IFT trends might be due to the crude oil and brine composition’s diversity . Some researchers did not consider the polar components in modeling the oil despite its essential impact on the IFT. , …”

Section: Introductionmentioning

confidence: 99%

Specificity and Synergy at the Oil–Brine Interface: New Insights from Experiments and Molecular Dynamics Simulations

et al. 2021

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The interfacial tension (IFT) between oil and brine is a key parameter affecting the enhanced oil recovery process. Despite the several theoretical and experimental investigations on the oil–brine system, the salinity effect on the IFT of oil–brine is still not fully understood. There is a contradiction in the literature rather than consistency. In the present study, we combine molecular dynamics (MD) simulations with the pendant drop method to investigate the molecular interactions at the oil–brine interface to better understand the salinity–IFT relationship. Herein, we are taking into account the complex composition of both crude oil and brine and the pH and total acid number. Different salinity conditions have been considered ranging from deionized water to connate (formation) water. We also consider the effects of individual brines of the main alkali salts (i.e., NaCl, MgCl2, and CaCl2) that are common in carbonate reservoirs. The specificity and synergy of the molecular interactions are observed via the confrontation of the results of the mixed brines (seawater and formation water) with those of the individual brines. We observed a significant impact of the divalent cations on the oil–brine interfacial tension. Due to the specificity of the organic acid–Ca2+ type of interaction and the synergy between the different ions, complete encapsulation of the Ca2+ ions has been observed within the formation water brine. This induces the depletion of the organic acids at the interface and thus increases the IFT. Such ionic encapsulation has not been observed in the individual brines because the cation–anion (Cl–) and the cation–water interactions are strong enough to prevent the cation–acid encapsulation. The interplay between the electrostatic interactions and the cations’ dehydration-free energies is the main parameter that controls their specificity and synergy, affecting the oil–brine interfacial properties. This work provides important details on the ionic interactions influencing the interfacial properties between crude hydrocarbons and brine.

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Preliminary Material

Abstract: This is an open access chapter distributed under the terms of the prevailing cc-by-nc License.

Cited by 2 publications

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Effects of Salinity and N-, S-, and O-Bearing Polar Components on Light Oil–Brine Interfacial Properties from Molecular Perspectives

Effects of Salinity and N-, S-, and O-Bearing Polar Components on Light Oil–Brine Interfacial Properties from Molecular Perspectives

Specificity and Synergy at the Oil–Brine Interface: New Insights from Experiments and Molecular Dynamics Simulations

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