Combined interfacial shear rheology and microstructure visualization of asphaltenes at air-water and oil-water interfaces

Abstract

Asphaltenes are surface-active polyaromatic molecules in crude oil that are known to deposit in pipelines or stabilize water droplets by flocculating at interfaces resulting highly viscous emulsions, leading to significant flow assurance problems. Commercial dispersants have been developed to disturb asphaltene aggregation to mitigate deposition, but their role on the interfacial properties of asphaltene films is unclear. In this study, we elucidate asphaltene interfacial rheology at air-water and oil-water interfaces at high and low asphaltene surface coverage and in the presence of dispersants. A modified Langmuir trough with double-wall ring rheometer is used to simultaneously visualize the microstructure of asphaltene interface and measure the rheological responses. Two surface coverages, 0.5 and 4 lg cm À2 , show widely different rheological responses at air-water interfaces. Strong yielding behavior was observed for higher coverage while a less yielding behavior and wider linear viscoelastic regime were observed for the lower coverage. Additionally, asphaltenes at decane-water interfaces were less shear-thinning than at air-water interfaces. Surface pressure-area compression-expansion curves show that the interface is more compressible in the presence of commercial chemical dispersants. This combined imaging and interfacial rheology platform provide an effective method to correlate asphaltene microstructure to interfacial rheological properties. V

Evaluating physicochemical properties of crude oil as indicators of low-salinity–induced wettability alteration in carbonate minerals

“…8[b]; R 2 = 0.62). The general trend agrees with the widely accepted premise that precipitated asphaltene can stabilize water-in-oil dispersion, probably due to the formation of an asphaltene rigid layer at the oil/water interface and its ability to provide electrostatic and steric repulsion for a repulsive disjoining pressure [62][63][64][65] . Duboue et al 49 .…”

Interference Provides Clarity: Direct Observation of 2D Materials at Fluid–Fluid Interfaces

“…The particles were allowed 15 min to equilibrate at the new decane–water interface after the turbulent spreading process before images were acquired. While it is known that the order of addition of the upper fluid phase during preparation of a fluid–particle–fluid system can influence interfacial morphology, e . g ., particles first, then oil, versus oil first, then particles, we do not expect the way in which we prepared the decane–water interfaces in this work to have significantly altered the optical properties of the system.…”

On the shear thinning of non-Brownian suspensions: Friction or adhesion?

“…Visualisation of dense particle suspension microstructure is challenging and thus optical imaging and actual quantification of the shear-induced characteristics of such systems has been fairly limited; to date very few relevant studies exist mainly focusing on smooth or spherical particles and biological samples, such as blood (Gunes et al, 2008;Kaliviotis et al, 2016;Lin et al, 2018;Ma et al, 2008;Massaro et al, 2020;Tanner, 2015;Varga et al, 2019).…”