High-Pressure Air Injection (HPAI) is an EOR process in which compressed air is injected into a deep, light-oil reservoir,with the expectation that the oxygen in the injected air will react with a fraction of the reservoir oil at an elevated temperature to produce carbon dioxide.Over the years, HPAI has been considered as a simple fluegas flood, giving little credit to the thermal drive as a production mechanism. The truth is that, although early production during a HPAI process is mainly due to repressurization and gasflood effects, once a pore volume of air has been injected the combustion front becomes the main driving mechanism. This paper presents laboratory and field evidence of the presence of a thermal front during HPAI operations, and its beneficial impact on oil production. Production and injection data from the Buffalo Field, which comprises the oldest HPAI projects currently in operation, were gathered and analyzed for this purpose. These HPAI projects are definitely not behaving as simple immiscible gasfloods.This study shows that a HPAI project has the potential to yield higher recoveries than a simple immiscible gasflood. Furthermore, it gives recommendations on how to operate the process to take advantage of its full capabilities

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Research described in this paper was conducted in support of a more extensive study that has been ongoing at the University of Calgary to quantify the effect of the presence of low levels of oxygen in the unheated portions of an Athabasca Reservoir undergoing in situ combustion and to evaluate if low temperature oxidation reactions could be used to achieve in situ upgrading. The objective of the overall program was to understand the compositional changes that might occur at temperatures ranging from those of the native reservoir to those experienced in a steam injection oil recovery process. The research program was originally started to quantify what were anticipated as detrimental compositional changes when oil is oxidized at native reservoir temperatures. The program was then extended to quantify the possible enhancement of the rate of cracking which might be achieved by oxidizing the oil at low temperatures, then heating it to temperatures typical of a steam injection operation. This paper will concentrate on the compositional changes of Athabasca bitumen in contact with nitrogen and air. The experiments were performed in an oscillating batch reactor with or without core and synthetic brine. The rate of oscillation was evaluated as a parameter to examine the role of mass transfer rates. Viscosity is reported in addition to the compositional data expressed in terms of the components: maltenes, asphaltenes and coke.The data has direct applicability to recovery processes involving the injection of air or a gas containing oxygen as an impurity. Typical applications of this nature include In-situ combustion, flue gas injection, and replacement of a gas cap with air or injection of CO 2 containing oxygen as an impurity.