Abstract: An in situ extraction process for heavy oil reservoirs using solvent comprises removing liquids and gases from areas contacting with the heavy oils to increase an interfacial area of unextracted heavy oil contactable by the solvent. Solvent vapor is injected into the areas to raise the reservoir pressure until sufficient liquid solvent is present to contact the increased interfacial area. The reservoir is shut in for a sufficient time for the solvent to diffuse into the unextracted oil across the interfacial area in a ripening step to create a reduced viscosity blend of solvent and oil. One or more reservoir characteristics is measured to confirm the extent of solvent dilution that has occurred of the unextracted oil in the reservoir. Gravity drainage based production is commenced from the reservoir upon the blend having a viscosity low enough to permit the blend to drain through the reservoir to a production well.

Abstract: There is disclosed a multi-step in situ extraction process for heavy oil reservoirs using a solvent having various steps, including, removing, from areas in contact with said heavy oil, solvent blockers to create voids and to increase an interfacial area of unextracted heavy oil contactable by said solvent and injecting solvent in vapour form into the voids to raise the reservoir pressure until sufficient solvent is present in a liquid form to fill the voids and to contact said increased interfacial area of said heavy oil. Next the reservoir is shut in for a period of time to permit said solvent to diffuse into said unextracted oil across said interfacial area from the solvent filled voids in a ripening step to create a reduced viscosity blend of solvent and oil and one or more reservoir characteristics is measured to confirm the extent of solvent dilution that has occurred of the unextracted oil in the reservoir.