A STEAM-ASSISTED GRAVITY DRAINAGE MODEL FOR TAR SANDS - LINEAR GEOMETRY

This paper presents a new predictive model for gravity drainage in tar sands during steam injection in linear geometry, e.g. along horizontal wells. The model has been validated against published experimental data. The model assumes that the steam zone shape is an inverted triangle with the lower vertex fixed at the production well The temperature profile in the oil is assumed to decline exponentially with distance away from the steam/oil interface, but unlike previously published models, the temperature decline is independent of position on the interface. An energy balance is used to determine the latent heat injection rate for steam to expand the steam zone, preheat the formation ahead of the steam zone, and balance heat losses to the overburden. The energy balance and oil production rate equations are combined to yield the steam-oil ratio for this process.