1. n. [Enhanced Oil Recovery]

An enhanced recovery process in which microorganisms are used in a reservoir to improve oil recovery. The microorganism can either be injected into the reservoir, or the population of an existing microorganism in the reservoir can be enhanced by injection of nutrients preferred by that microorganism. The microorganisms improve oil recovery by various means:

• by releasing gases and increasing the pressure of the reservoir
• by breaking the heavier molecules into smaller chain components, resulting in the reduction of viscosity of oil
• by producing natural surfactants that can improve oil flow by altering the interfacial properties of the system comprising the crude oil, brine and rock.