Evolution and Interfacial Dynamics of Thin Electrolyte Films in Oil–Brine–Carbonate Rock Systems due to Chemical Equilibrium Disruptions

Abstract

This study presents the interfacial dynamics of viscoelastic thin electrolyte films between crude oil and rock surface, by integrating the effects of salt type and concentrations into the nonlinear evolution equation for viscoelastic thin liquid films. Dimensionless interfacial tension (IFT) is calculated for crude oil− NaCl, Na 2 SO 4 , MgCl 2 , MgSO 4 , CaCl 2 , and CaSO 4 interfaces. Subsequently, the interfacial dynamics of the electrolyte films (bulk phase) are evaluated at selected characteristic viscoelastic parameters and various exposure times. Results show that chloride salts of Na + , Mg 2+ , and Ca 2+ have lesser deteriorating effects on thin-film integrity compared with sulfate salts of the same cations while the presence of 1000 ppm MgCl 2 proves to constitute the least barrier to the stability of thin films. Contact angle is the most critical parameter affecting film dynamics, followed by crude oil−brine interfacial tension and the viscosity of thin electrolyte films. The difference between the ζ-potentials calculated at the crude oil−brine interface and at the brine−rock interface is a major factor in determining the response of thin electrolyte films to perturbations. A large difference between the two values of ζ-potential at the interfaces leads to better resistance to perturbations. Evaluation of the interfacial dynamics of viscoelastic thin electrolyte films is, therefore, a reliable method to determine wettability alteration due to smart water effects.