Many of the Lloydminster-type heavy oil reservoirs are unsuitable for thermal recovery by steam injection because they are relatively thin and the heat losses to the under- and overburden are excessive. To overcome this difficulty, a new approach has been proposed which utilizes the injection of saturated hydrocarbon vapours at approximately reservoir temperature. There are several modifications of the basic principle under development in which the amount of extraneous heat injected varies from none to moderate, and the vapour chamber is maintained at reservoir temperature to 30°C above it. This flexibility allows the approach to be followed for the recovery of both conventional heavy oils and for bitumen.

The method, termed "Vapex", utilizes two horizontal wells and is closely related to the SAGD process but with the steam chamber replaced by a chamber containing hydrocarbon vapour near its dew point.

The quality of bitumen or heavy oil can be improved substantially by in situ deasphalting with propane vapour. The removal of asphaltenes reduces the viscosity of the produced oil and creates an oil that is more easily refined.

In this paper we present new experimental results obtained in a scaled physical laboratory model and discuss the effect of factors such as injected G/O ratio, different saturation pressures and vapour chamber temperatures on the rate of oil production, the extent of in situ deasphalting and the quality of the recovered oil.

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