Numerical simulation of combined reverse combustion and steamflooding for oil recovery in a Utah tar sand

This paper presents the design of the U.S. DOE Laramie Energy Technology Center's (LETC) Project TS-4, which involves numerical simulation of both in-situ reverse combustion and steamflooding. The simulator showed that the combustion could be limited and contained in a middle 10-ft [3-m] interval with a correlatable high-permeability streak within the 65-ft [20-m] pay zone of the upper Rimrock tar sand formation in Northwest Asphalt Ridge, Uintah County, UT. A high-transmissibility path was necessary 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 by steam injection was accelerated in a formation preheated by a reverse combustion.