This paper presents the design of the US-DOE Laramie Energy Technology Center’s projects TS-4 which involve both in-situ reverse combustion and steam flooding, using a numerical simulator. The simulator showed that the combustion could be limited and contained in a middle 10-foot interval with a correlatable high permeability streak within the 65-foot pay zone of the upper Rimrock tar sand formation in Northwest Asphalt Ridge, Ulntah County, Utah. A high transmissibility path was assumed to obtain adequate injectivity and sustain a stable reverse combustion. Combustion ‘echoes’ developed and the front changed into a forward mode as the formation pressure increased and at very low air-injection rates. Oil recovery was accelerated by pre-heating the formation with the combustion before steam flooding the entire sand.