Enhanced Oil Recovery

Enhanced Oil Recovery (EOR, also Tertiary Oil Recovery (TOR ); German: enhanced oil recovery ) is a generic term for technologies that enable an increased yield of oil production.

Wherein the primary and secondary oil recovery methods, the yield is from 20 to 40%. Through the use of various techniques of tertiary methods, the oil yield can be 30 - 60 % increase.

Methods

There are various methods of EOR, such as the gas injection, the injection of chemicals, mainly surfactants, ultrasonic stimulation, the injection of microbiologically active cultures or thermal methods, such as through injection of steam.

Gas Injection

Gas injection is a commonly used method. In this case, gas is supplied under high pressure into the well to force the oil to the surface. In addition to the purely mechanical property of the gas occur in some positive effects by a reduction in viscosity. These are due to the fact that the gas is partially dissolves in the oil and thus reduces the viscosity. Commonly used gases are carbon dioxide, nitrogen or natural gas.

Injection of chemicals

Various types of chemicals, such as polymers and detergents may be used. These should either reduce the viscosity of the crude oil or increase of the water that is injected to drive the oil to the surface.

Ultrasonic techniques

Various ultrasound techniques have been proposed. In this case, the drill bit is to be modified so that a piezoelectric ultrasonic vibration is transmitted to the surrounding rock to enable a detachment of the oil droplets.

Injection microbiologically active cultures

Injection microbiologically active cultures is not particularly widespread, but is currently intensively researched. This also genetically modified microbes are explored, which should either be prepared from long-chain oil constituents biosurfactants, or strains that produce CO2. The injection of the cultures performed with culture media, staggered about with carbohydrates water. It is also trying to promote the growth of bacteria found in soils by feeding nutrient media.

Another approach is the use of microbes, which are intended to break down the long chain paraffins in crude oil occurring in the short-chain and thus reduce a one stocking up the oil in the promotion.

Thermal recovery

In thermal recovery, such as the injection of steam, the lower the viscosity of the crude oil is in the foreground.

Cost and advantages

The cost - benefit analysis of EOR methods depends on the current price of oil. In times of relatively low oil prices tertiary methods are not generally used. The gain may be as up to U.S. $ 100 per tonne of crude oil in times of high oil prices.