Enhance Oil Recovery

DefinitionEnhanced Oil Recovery (abbreviated EOR) is a generic term for techniques for increasing the amount of crude oil that can be extracted from an oil field.

Enhanced oil recovery is also called improved or tertiary Recovery (as opposed to primary and secondary recovery).

Using EOR, 30-60%, or more, of the reservoir's original oil can be extracted, compared with 20-40% using primary and secondary recovery.

Types of Enhance Oil Recovery MethodsFollowing are the methods of Enhance Oil Recovery,

1, Gas Injection2, Chemical Injection3, Microbial Injection4, Thermal methods

Gas InjectionGas re-injection is presently the most-commonly used approach to enhanced recovery. this method sometimes aids recovery by reducing the viscosity of the crude oil as the gas mixes with it.

Gases used include CO2, natural gas or nitrogen. Air cannot be used to re-pressurize the reservoir because the oil will quickly catch on fire.

In CO2 injection, more than half and up to two-thirds of the injected CO2 returns with the produced oil and is usually re-injected into the reservoir to minimize operating costs. The remainder is trapped in the oil reservoir by various means.

Chemical InjectionThe injection of various chemicals, usually as dilute solutions, have been used to improve oil recovery.

Injection of alkaline or caustic solutions into reservoirs with oil that has organic acids naturally occurring in the oil will result in the production of soap that may lower the interfacial tension enough to increase production.

Polymers, Surfactants and Bio surfactants are added to the water to lower the interfacial tension of crude oil, that impedes a droplet of crude to flow.

Microbial InjectionMicroorganisms are very diverse; they include bacteria, fungi, archaea, and protists; microscopic plants (green algae); and animals such as plankton and the planarian.

Microbial injection is part of microbial enhanced oil recovery and is presently rarely used, both because of its higher cost and because the developments in this field are more recent than other techniques.

Strains of microbes have been both discovered and developed (using gene mutation) which function either by partially digesting long hydrocarbon molecules, by generating biosurfactants.