Abstract: Steam assisted gravity drainage (“SAGD”) is practised in a first section of a reservoir containing heavy oil. When steam/oil ratio rises sufficiently, steam injection into the first section is curtailed or terminated. Non-condensible gas is then injected into the section to pressurize it and production of residual oil and steam condensate is continued. Concurrently with pressurization, SAGD is practised in an adjacent reservoir section. As a result, some of the residual oil in the first section is recovered and steam loss from the second section to the first section is ameliorated.

Abstract: An in-situ combustion method is provided for the recovery of viscous oil from an oil-bearing reservoir. A linear array of vertical air injection wells is drilled into the reservoir; the wells are completed in the upper portion of the reservoir. One or more gas production wells are provided, remote from the row of injection wells, said gas production wells also being completed in the upper portion of the reservoir. A horizontal oil production well is completed in the bottom portion of the reservoir, aligned with and positioned in spaced relation beneath the vertical injection wells. The reservoir is prepared for ignition and combustion is initiated at each of the injection wells. A hot fluid-transmissive chamber is formed around each of the injection wells as combustion proceeds. Combustion gas communication is established with the gas production wells.

Abstract: The invention has application only to a first oil well producing oil having a high water cut, said oil well being completed in a reservoir having an increased gas saturation, in the vicinity of the first oil well, arising from injection of gas through an adjacent injection well. The first oil well is treated by injecting through it into the reservoir a slug of non-condensible gas in an amount between about 40,000 m.sup.3 and 200,000 m.sup.3. The first well is then placed back on production and its water cut is significantly reduced.

Abstract: An oil well producing water is treated to reduce the water cut by injecting through the well into the reservoir a composite slug comprising:a relatively small volume of water-wetting agent in liquid form, said agent being adapted to modify the reservoir matrix to increase its water-wetted character; anda relatively large volume of non-condensable gas for further laterally extending the matrix surface modification.