A study of bitumen recovery by gravity drainage using low temperature soluble gas injection

A gravity drainage concept has been proposed and tested for in-situ recovery of bitumen by mobilization with soluble gases at ambient reservoir temperature conditions. Experiments were done using carbon dioxide and ethane gases at ～ 20°C to recover Athabasca bitumen from a scaled reservoir model. Thermal gravity drainage theory has been modified for the mass transfer case. The measured drainage rates were higher than those predicted by the model using molecular diffusivity data but fit the model better using an increased effective diffusivity. Lateral dispersion theory does not predict the high measured effective diffusivities. A preliminary economic evaluation of field production indicates potential application to recovery of Lloydminster heavy oil.