Gas flooding: Gas Enhanced Oil Recovery (G-EOR) to CO₂ sequestration

One of the most accepted and widely used technologies for enhanced oil recovery (EOR) is gas flooding. Understanding the gas flooding requires a good understanding of the interaction of phase behavior and flow in the reservoir as well as surface separation technologies and compression processes. After a brief introduction to what gas flooding is, this chapter begins by examining the phase behavior that results from mixing gas and oil and how this can release previously trapped oil from the reservoir. We then explain how miscibility is developed in situ for a variety of gas flood mechanisms that occur in real field displacements. We also discuss CO2 injection to sequester carbon dioxide, whether that be in deep brine reservoirs or in depleted oil reservoirs. Last, we examine field cases to quantify the level of recoveries that have been achieved from gas flooding projects and summarize field problems that have been experienced.