NUMERICAL SIMULATION OF THERMAL SOLVENT REPLACING STEAM UNDER STEAM ASSISTED GRAVITY DRAINAGE (SAGD) PROCESS

Steam Assisted Gravity Drainage (SAGD) is one successful thermal recovery technique applied in Athabasca reservoir to produce the in‑situ high viscosity bitumen. To remove the limited supply and expensive water treatment required in SAGD process, injecting high temperature solvent instead of steam is investigated in this study. In this study, hexane co‑injection under Athabasca reservoir condition is simulated to analyze the drainage mechanism in the high temperature solvent chamber. The production performance is compared with the steam injection case. The study shows that hexane is vaporized and transported to the solvent chamber boundary. The phase change of hexane, from vapor to liquid, can reduce the bitumen viscosity efficiently and replace all the original oil out. The production rate under thermal solvent process is about 1.5 times of steam injection case. This study also shows that almost all the injected hexane can be recycled easily by re‑vaporization process. From this study, thermal solvent can successfully remove the requirement of steam injection in SAGD process with higher production rate and higher recovery factor. With hexane recycling process, the required large solvent injection volume will not limit its application.