Pore-Scale Displacement of Heavy Crude Oil During Low Salinity Water Flooding

• Published in: Transport in porous media 2022-10, Vol.145 (1), p.73-101
• Main Authors: Babakhani Dehkordi, Parham, Razavirad, Fatemeh, Shahrabadi, Abbas
• Format: Article
• Language: English
• Subjects: Civil Engineering; Classical and Continuum Physics; Clay; Contact angle; Contact potentials; Crude oil; Displacement; Earth and Environmental Science; Earth Sciences; Enhanced oil recovery; Flooding; Fourier transforms; Geotechnical Engineering & Applied Earth Sciences; Glass plates; Heavy petroleum; Hydrogeology; Hydrology/Water Resources; Industrial Chemistry/Chemical Engineering; Oil recovery; Porous media; Reduction; Salinity; Seawater; Surface tension; Water flooding; Wettability; Zeta potential
• ISSN: 0169-3913; 1573-1634
• DOI: 10.1007/s11242-022-01825-0

To date, most studies about low salinity water flooding (LSWF) have been conducted at the Darcy scale, taking into account mixed-wet conditions, although a limited number of studies have investigated interactions of heavy crude oil/LSWF/rock system from a pore-scale perspective. Consequently, the mechanisms responsible for EOR during LSWF, particularly, within oil-wet porous media are not well understood. The current study investigates pore-scale dynamic of LSWF displacement (forced imbibition and drainage tests) within clean and clayey 2D glass micromodels by setting the initial wettability of the systems as both water-wet and oil-wet. Before performing oil displacement tests at the pore-scale, preliminary evaluations at sub-pore-scale, including zeta potential, interfacial tension (IFT), contact angle, Fourier Transform Infrared Spectroscopy (FTIR), and micro-dispersion tests were conducted. Irrespective of the absence or presence of clay particles, LSWF showed a positive response to increased oil recovery, though its influence is not significant. The main mechanisms responsible for oil recovery enhancement were observed to be snap-off reduction and formation of water micro-dispersion within clay-free hydrophilic and hydrophobic porous media, respectively, which eventually leads to wettability alteration toward more water-wet conditions. This evidence is supported by the reduction in contact angle between crude oil/glass-plate models when switching from seawater to LSWF. The results of zeta potential measurements indicate that decreases in brine salinity leads to more negative values, which can cause double layer expansion, and wettability alteration. These factors are the main controlling mechanisms during LSWF within clay-coated porous medium since fine migration was not significantly observed in the micromodel.