TY - JOUR
T1 - Salinity-Driven Structural and Viscosity Modulation of Confined Polar Oil Phases by Carbonated Brine Films
T2 - Novel Insights from Molecular Dynamics
AU - Mirzaalian Dastjerdi, Ali
AU - Kharrat, Riyaz
AU - Niasar, Vahid
AU - Ott, Holger
N1 - Publisher Copyright: © 2024 American Chemical Society.
PY - 2024/2/9
Y1 - 2024/2/9
N2 - 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 two-phase 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.
AB - 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 two-phase 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.
KW - Calcite
KW - Ions
KW - Lipids
KW - Molecule
UR - https://doi.org/10.1021/acs.jpcb.3c07300
UR - http://www.scopus.com/inward/record.url?scp=85185716987&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.3c07300
DO - 10.1021/acs.jpcb.3c07300
M3 - Article
SN - 1089-5647
VL - 128.2024
SP - 1780
EP - 1795
JO - Journal of physical chemistry (B, Condensed matter, materials, surfaces, interfaces, & biophysical chemistry)
JF - Journal of physical chemistry (B, Condensed matter, materials, surfaces, interfaces, & biophysical chemistry)
IS - 7
ER -