FURTHER IMPROVEMENTS IN PORE SCALE STUDIES OF SAGD PROCESS

Steam Assisted Gravity Drainage method was developed, pilot tested, and commercialized in Canada. This process has been proven successful in producing unconventional oil resources at a high production rate and economical steam‑to‑oil ratios. With a quick review over the published SAGD literature, lack of a comprehensive pore‑level mechanistic study is observed. A series of visualization studies of the SAGD process were developed earlier to capture the pore‑level physics of the process using qualitative analysis. The main objective of this paper is to present recent improvements made in this regard using glass micromodels. Experiments were conducted inside an environmental vacuum chamber to reduce the excessive heat loss to the surrounding while steam was injected under different superheating levels. Local temperatures along the model's height and width were recorded on a real time basis. Visualization results were analyzed using image processing techniques. The results indicated that near a well‑established oil‑steam interface, gravity drainage takes place through a thick layer of pores within the mobilized region. The interplay between gravity and capillarity forces results in the drainage of mobilized oil. Moreover, the phenomenon of water‑in‑oil emulsification at the interface were also demonstrated which is due to the local steam condensation. The extent of emulsification directly depends on the temperature gradient between the steam and bitumen phases. Other pore‑scale aspects of the process such as drainage displacement mechanisms of the mobilized oil, localized entrapment of steam bubbles as well as condensate droplets within the mobilized oil continuum due to capillarity phenomenon, sharp temperature gradient along the mobilized region, co‑current and counter‑current flow regimes at the chamber walls, condensate spontaneous imbibition followed by mobilized oil drainage, and local heat transfer mechanisms are also illustrated using these pore‑level studies of the SAGD process.