Effects of polar fractions on interfacial and bulk properties at the oil/carbonated aqueous solution interface: Insight from molecular dynamics simulation

Mirzaalian Dastjerdi, Ali; Kharrat, Riyaz; Niasar, Vahid; Ott, Holger

doi:10.1016/j.colsurfa.2023.132660

Cited by 2 publications

(3 citation statements)

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“…BA represents the polar fraction of natural organic matter in underground petroleum and water resources. It mimics carboxylic acids with an aromatic ring, accounting for the key characteristic of the polar fraction of crude oil. − Initially, the calcite silts mimic nanopores with an aperture of 7 nm in the z -direction. To study the effects of carbonated water, a thin brine film that covers each calcite slab enriched with carbon dioxide was employed.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, we demonstrated that the presence of polar fractions results in a more pronounced influence of CO 2 on the fluidity of the oil phase than IFT reduction. 31 However, there remains a lack of concrete experimental or simulation studies elucidating the molecular mechanisms behind changes in oil viscosity due to carbon dioxide transfer from the water phase to the oil phase in an oil layer confined by the brine. Furthermore, the effect of polar aromatic components, as the principal part of asphaltenes, has not yet been investigated in this resolution.…”

Section: Introductionmentioning

confidence: 99%

“…As demonstrated, CO 2 exhibits significant mass transfer from the brine into the oil phase, reducing oil viscosity and improving the oil–water mobility ratio. Recently, we demonstrated that the presence of polar fractions results in a more pronounced influence of CO 2 on the fluidity of the oil phase than IFT reduction . However, there remains a lack of concrete experimental or simulation studies elucidating the molecular mechanisms behind changes in oil viscosity due to carbon dioxide transfer from the water phase to the oil phase in an oil layer confined by the brine.…”

Section: Introductionmentioning

confidence: 99%

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Salinity-Driven Structural and Viscosity Modulation of Confined Polar Oil Phases by Carbonated Brine Films: Novel Insights from Molecular Dynamics

Dastjerdi,

Kharrat,

Niasar

et al. 2024

J. Phys. Chem. B

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The structural and dynamic properties of fluids under confinement in a porous medium differ from their bulk properties. This study delves into the surface structuring and hydrodynamic characteristics of oil/thin film carbonated brine twophase within a calcite channel upon salinity variation. To this end, both equilibrium and non-equilibrium molecular dynamics simulations are utilized to unveil the effect of the carboxylic acid component (benzoic acid) in a simple model oil (decane) confined between two thin films of carbonated brine on the oil−brine− calcite characteristics. The salinity effect was scrutinized under four saline carbonated waters, deionized carbonated water (DCW), carbonated low-salinity brine (CLSB, 30,000 ppm), carbonated seawater (CSW, 60,000 ppm), and carbonated high-salinity brine (CHSB, 180,000 ppm). An electrical double layer (EDL) is observed at varying salinities, comprising a Stern-like positive layer (formed by Na + ions) followed by a negative one (formed by Cl − ions primarily residing on top of the adsorbed sodium cations). By lowering the salinity, the Na + ions cover the interface regions (brine−calcite and brine−oil), depleting within the brine bulk region. The lowest positive surface charge on the rock surface was found in salinity corresponding to seawater. Two distinct Na + peaks at the oleic phase interface have been observed in the carbonated high-salinity brine system, enhancing the adsorption of polar molecules at the thin brine film interfaces. There is a pronounced EDL formation at the oleic phase interface in the case of CSW, resulting in a strong interface region containing ions and functional fractions. Likewise, the oil region confined by CSW exhibited the lowest apparent viscosity, attributed to the optimized salinity distribution and inclination of benzoic acid fractions uniformly at the brine− oil interface, acting as a slippery surface. Moreover, the results reveal that the presence of polar fractions could increase the oil phase's apparent viscosity, and introducing ions to this system reduces the polar molecules' destructive effect on the apparent viscosity of the oil region. Therefore, the fluidity of confined systems is modulated by both composition of the brine and oil phases.

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