Chemical Additives Assist Oil-in-Water Emulsion Formation in SAGD

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 212779, “Oil-in-Water Emulsion Formation in SAGD With Chemical Additives,” by S. Ali Ghoreishi, University of Calgary, and Javier O. Sanchez and Julian D. Otiz-Arango, ConocoPhillips, et al. The paper has not been peer reviewed. The study detailed in the complete paper aims at understanding the effect of a surfactant that the authors refer to as a high-temperature emulsifying agent (HEA) as an additive in the steam-assisted gravity drainage (SAGD) process. The work provides insights into the role of surfactants in forming oil-in-water (O/W) emulsions in steam-based bitumen production. A novel high-pressure/high-temperature (HP/HT) visual cell enables the rapid assessment of recovery processes and a better understanding of the active emulsifying mechanism in such a system. The authors conducted a pore-network micromodel experiment to analyze the effect of emulsifiers on the SAGD process. Hot water, with and without a priority emulsifying agent, was injected into a bitumen-saturated micromodel at 82°C. The surfactant solution can remove the residual oil from the invaded zone and forms O/W emulsions as it spreads in uninvaded regions. The experimental setup includes a high-resolution imaging system, a lightbox, a precision syringe pump, a bitumen-transfer vessel, and an HP/HT cell (Fig. 1a). A borosilicate glass micromodel (Figs. 1b and 1c) was placed inside the vertical HP/HT cell, and the remaining space in the HP/HT cell was filled with a heat-resistant mineral oil. The heating jacket was mounted on the HP/HT cell, and a digital thermometer was connected to the heating jacket and placed between the heating jacket and the cell to monitor and control the temperature. The micromodel inlet was connected to the syringe pump. The remainder of the experimental process is detailed in the complete paper. Effect of HEA on Emulsion Formation and Sweeping Patterns. In all experiments, the hot aqueous phase was injected at the rate of 5 μL/min into the micromodel fully saturated with Athabasca bitumen. The HP/HT cell was kept at a constant temperature of 82°C. The hot water injection was used as the base system to be compared with the HEA-solution injection. Water droplets trapped in the pockets of bitumen phase were observed at the later stages of displacement in flooded areas near the two-phase interface. Water droplets were first formed at the top of the micromodel, close to the injection port, and were pushed down toward the production port as injection continued. O/W droplets, in a much lesser quantity, also were formed during the displacement process close to the production port. An HEA solution with a concentration of 3,000 ppm was injected under the same conditions as the hot-water-injection scenario. The HEA solution also formed a chamber at the top of the micromodel with an advancing finger toward the production port. The injection of HEA solution completely cleaned the surface of the pores.​​​​​