STEAM-ASSISTED GRAVITY DRAINAGE - CONCEPT, DEVELOPMENT, PERFORMANCE AND FUTURE

In the Steam-assisted Gravity Drainage (SAGD) process, heated oil drains from around growing steam chambers, driven by gravity, to lower horizontal wells. As the oil drains, the steam chamber advances into the reservoir. The process has several features: The displacement of the oil is systematic and high recoveries can be obtained. In suitable applications, oil to steam ratios higher than those found for conventional steamflooding can be achieved. The process can be used in even the heaviest of bitumen reservoirs without extensive preheating. The feature which makes this possible is that once the oil is heated, it remains hot as it drains to the production well; this is unlike conventional steamflooding where oil which is displaced from the steam chamber tends to cool on its way to production.