Oil in Water Emulsion Formation in SAGD with Chemical Additives

Abstract

Abstract The in-situ formation of oil in water emulsions can contribute to the oil mobilization when combined with Steam-Assisted Gravity Drainage (SAGD). The produced fluids in SAGD operations and sand pack SAGD experiments often show the existence of both oil in water and water in oil emulsions. Due to the opaque nature of sand packs, however, it is unclear whether the emulsions are formed in-situ during the flow through porous media or in the production tubing. This study aims at understanding the impact of a surfactant known as "High-temperature Emulsifying Agent" (HEA) as an additive on the SAGD process and the possibility of forming preferred oil in water emulsions. The high-temperature fluid flow experiments are performed in 2.5D glass micromodels which are placed in a custom built compact high pressure-high temperature (HPHT) visual cell. Hot water and HEA solution (3000 ppm concentration) at 82 °C are injected at a constant rate of 5 μl/min. The injected fluid first displaces bitumen in the form of an advancing finger, forming a condensate-bitumen interface which is slowly advancing towards the production port at the bottom end of the model. Hot water initially displaces bitumen from the pores leaving a film of bitumen on the grain surfaces which is eventually removed as the injection continues. Water droplets dispersed in bitumen are observed at the areas experiencing high shear forces, i.e., near the main two-phase front and close to the production port. In contrast to the hot water process, no oil film is observed during the HEA injection. In the presence of HEA solution, oil in water emulsion is formed at the condensate-bitumen interface and ahead of the interface deep in the oil zone. The latter could be the result of corner flow which promotes the fast distribution of HEA solution throughout the model, ahead of the main water-oil interface. This work provides insights on the role of surfactants in forming oil in water emulsions in steam-based bitumen production. A novel HPHT visual cell enables the rapid assessment of solvent-surfactant-steam recovery processes and a better understanding of the active emulsifying mechanism in this system.