Combined steam and vapor extraction process (SAVEX) for in situ bitumen and heavy oil production

A process for recovery of hydrocarbons from an underground reservoir of said hydrocarbon, the underground reservoir being penetrated by an injection well and a production well spaced from the injection well, the process comprising:

• (a) injecting steam into said reservoir thereby heating said reservoir to mobilize and recover at least a fraction of reservoir hydrocarbons and to form a steam chamber in said reservoir;
• and then,
• (b) continuing to inject steam into said reservoir and mobilize and recover reservoir hydrocarbons therefrom until an upper surface of said chamber has progressed vertically to a position that is at least approximately 25 percent to 75 percent the distance from the bottom of injection well to the top of the reservoir;
• and then,
• (c) injecting into the reservoir a viscosity-reducing hydrocarbon solvent, said solvent being capable of existing in vapor form in said chamber and being just below said solvent's saturation pressure in said chamber, thereby mobilizing and recovering an additional fraction of hydrocarbons from the reservoir.

A process for recovery of hydrocarbons from an underground reservoir of said hydrocarbons, the underground reservoir being penetrated by an injection well and a production well spaced from the injection well, the process comprising:

• (a) injecting steam into said reservoir thereby heating said reservoir to mobilize and recover at least a fraction of reservoir hydrocarbons and to form a steam chamber in said reservoir;
• and then,
• (b) continuing to inject steam into said reservoir and mobilize and recover reservoir hydrocarbons therefrom until the recovery rate of said hydrocarbons is at least approximately 25 percent to 75 percent of the peak predicted recovery rate using steam-assisted gravity drainage;
• and, then,
• (c) injecting into the reservoir a viscosity-reducing hydrocarbon solvent, said solvent being capable of existing in vapour form in said chamber and being just below said solvent's saturation pressure in said chamber, thereby mobilizing and recovering an additional fraction of said hydrocarbons from the reservoir.