Combustion tube experiments on key factors controlling the combustion process of air injection with light oil reservoir

Abstract

High pressure air injection (HPAI) has unique advantages due to its rich gas source and unique high-energy displacement effect of the thermal front. Thermal effect of air injection after combustion is the key factor affecting the oil displacement effect. Combustion tube experiments are conducted to study the combustion characteristics of light oil and the influence of different factors on combustion process. We find that light oil (content of asphaltene is only 1.13%) can be ignited and combustion front can advance forward stably, which proves that the implement of HPAI in light oil reservoir can achieve good results. High temperature makes combustion more intense and the advancing of combustion front more stable. The experimental results show that when the air injection rate is low, low temperature oxidation of light oil will dominant, or the combustion front cannot successfully advance. But when the injection rate is too high, the combustion front moves forward too fast and gas channeling will occur. With pressure increasing, the solubility of O2 in oil increases, causing a more violent oxidation reaction. Increasing pressure can reduce the air/oil ratio and improve the utilization rate of O2. Thus, HPAI is more ideal for the reservoirs with high temperature and high pressure. And for a specific reservoir, an optimal injection rate exists. The conclusions of the research can provide references for field applications of HPAI in light oil reservoirs.