Patent ID: 8434551

Claim:
A method of forming an in situ gravity drainage chamber while extracting hydrocarbons from a hydrocarbon bearing formation, the method comprising: injecting a condensing solvent into said chamber to extract non-condensable gases from said chamber in liquid form; monitoring a growth of said chamber in a vertical direction; and accumulating a non-condensable barrier gas in a layer at a top of said chamber by the further steps of a) stopping said condensing solvent injection, b) commencing barrier gas injection to establish the non-condensable barrier gas layer at said top of said chamber, c) stopping said non-condensable barrier gas injection, and d) restarting said condensing solvent injection below said non-condensable barrier gas layer to extend said growth of said chamber in a generally horizontal direction; wherein at in situ conditions said non-condensable barrier gas is less dense as compared to said condensing solvent, and said non-condensable barrier gas layer limits: (i) further vertical growth of said chamber at or before said chamber reaches an overburden layer; or (ii) further vertical heat flow from said chamber at or before said chamber reaches said overburden layer.