Effect of Interstitial Water Saturation and Air Flux on Combustion Kinetics of High Pressure Air Injection HPAI

Abstract

Abstract High Pressure Air Injection (HPAI) in deep light oil reservoirs has received notable attention in the last three decades after its successful field application in 1979. Kinetics of the oxidation reactions associated with HPAI are important for understanding the mechanism which control the overall performance of air injection processes; however, they are not yet fully defined. This paper describes the results of an experimental study conducted to characterize some main parameters which impact the reaction kinetics of light oil oxidation/combustion in HPAI. Vaporization of oil has been recognized as important mechanism controlling the nature of the residual oil that is the source of the fuel for light oil combustion; however, the parameters controlling vapor phase oxidation/combustion have not been included in the studies of oxidation kinetics. Interstitial water saturation plays an important role on phase behavior and heat transfer and consequently the reaction kinetics. However, there is no reported data in literature investigating this factor. This study aims to shed light on these unknown aspects of light oil air injection (HPAI). Several oxygen and nitrogen injection experiments have been performed on a recombined light oil and also a pure oil component sample in a 45 cm long, high pressure ramped temperature oxidation (HPRTO) reactor. Experiments were run in the presence and absence of interstitial water at two different levels of air and nitrogen injection flux. This paper concentrates on selected tests which highlight the effects of interstitial water, injection flux, and oil type on oxidation/combustion behavior of light oils under HPAI. An endothermic evaporation front was observed to precede the thermal front in low flux air injection tests. Interstitial water saturation had a major contribution to endothermic heat of vaporization and the tests with no recombined water barely developed a distillation wave. Observations in this study highlight the significant impact of phase behavior on oxidation/combustion behavior of light oils in HPAI.