High-Pressure Air Injection for Improved Oil Recovery: Low-Temperature Oxidation Models and Thermal Effect

摘要

High-pressure air injection into light oil reservoirs is an effective technique for improved oil recovery (IOR), and this technique mainly depends upon a spontaneous low-temperature oxidation (LTO), which occurs at original reservoir temperatures. During the LTO process of air injection, oxygen in the injected air is consumed and carbon dioxide can be produced in the reservoir, leading to flue gas flooding and producing a significant amount of heat. In this paper, the mechanisms of the LTO reaction are analyzed and an improved LTO reaction model is established to facilitate reaction mechanism and reservoir simulation studies. A series of high-pressure LTO experiments using typical light oils were carried out in a temperature range from 70 to 170℃ to measure the reaction rates and to reveal the exothermic behavior of the LTO reactions. Heat-transfer analysis in the experimental process was conducted to examine the exothermic characteristics of the reaction using different reactors and at various experimental conditions. A conceptual reservoir simulation model was used to study the thermal effect of the LTO reaction during the air injection process in terms of the temperature rise in the reaction zone and its IOR effect.