Enhanced Oil Recovery

Enhanced oil recovery (EOR) techniques are used to increase both the amount of oil recovered and the rate at which it is recovered. EOR techniques include thermal recovery processes (steam injection and in situ combustion), gas injection (carbon dioxide injection), chemical injection (polymer injection) and microbial enhanced oil recovery. Thermal-enhanced oil-recovery techniques seek to improve recovery by heating the oil within the formations. When an oil is heated its viscosity will decrease, allowing the oil to flow more easily towards the production wells. The heat can either be generated at the surface and then injected underground in the form of steam, or within the formation itself by burning a portion of the oil in place. In situ combustion processes have been successful in producing oil by the partial combustion of the heavy ends of the oil, which are less likely to be recovered. Today, carbon-dioxide injection dominates the new EOR projects coming on stream. When carbon dioxide is dissolved in oil, the viscosity of the oil will drop significantly, making the oil more mobile. If carbon dioxide can be injected under the right set of conditions then the amount of oil produced will increase significantly. This chapter also reviews other EOR techniques including polymer injection, surfactant injection and alkaline injection. The use of micro-organisms that will thrive underground is also described. Finally, we consider the exploitation of the Weyburn Field in Canada. By progressively applying different techniques the field continues to produce oil after more than 50 years.