A study of oil displacement on model surfaces

Experiments were performed to study bitumen film rupture and displacement on model surfaces, Bitumen film on a glass plate was found to thin down and rupture in the presence of water having a high pH; whereas on a polytetrafluoroethylene surface, film rupture did not take place. Experimental results on the rate of bitumen/water contact line displacement on a glass surface are also reported. A thin coating of bitumen on a glass surface retracted spontaneously in the inward radial direction upon exposure to an aqueous environment. The initially circular bitumen disk was reshaped into a spherical droplet. The time variation of the apparent dynamic contact angle of bitumen on the glass surface was measured at different pH and temperature. Finally the equilibrium contact angle of the bitumen on the glass surface was also measured. The bitumen displacement rate on the glass plate is higher at lower pH and the corresponding equilibrium contact angle is smaller. The rate of bitumen displacement increases with a decrease in the initial bitumen volume, The water temperature has minimal effect on the equilibrium contact angle; however, it has a significant influence on the bitumen displacement rate through changes in the bitumen viscosity. The displacement of a three-phase contact line is modeled using a simple force balance at the contact line. The experimentally measured dynamic contact angle is predicted well by the proposed model. The dynamic contact angle predictions by other contact line displacement models were compared with the experimental data. The practical implications of these results for bitumen extraction from oil sands are discussed. (C) 1996 Academic Press, Inc.