Oil pump and oil well
In 1937 well RAG 2 (Zistersdorf concession) hit the first oil in Austria.
Today RAG operates 86 oil production wells in the Upper and Lower Austrian fields with a total annual production of approx. 105000 tons (2008).
Scheme production methods
Scheme surface - subsurface
Oil production methods
Before oil is produced, the borehole (well) is equipped with tubing and is perforated in the reservoir section.
In a first phase, oil flows in the reservoir towards the production wells because of the natural reservoir pressure, and erupts to the surface. When the pressure drops artificial lift methods are required.
In the so-called gas-lift process compressed gas is injected via the casing-tubing annulus into the production string. The rising gas reduces the weight of the liquid column and the free-flowing phase of the well can be extended.
If the oil contains little gas and reservoir pressure drops, sucker rod pumps are installed. At the surface, one can see only the drive mechanism, the so-called beam pump with the typical horsehead. When production rates are high electrical submersible pumps are installed in the borehole.
When circumstances are favorable, for instance strong water drive and excellent reservoir quality, primary oil recovery may be beyond 50 %. However, if reservoir pressure is weak or oil viscosity high, the primary recovery rate may just be 5 to 15 % of the original reservoir content.
The water cut continuously rises during production. Depending on the circumstances even a water content of more than 95 % may allow for economic production.
The produced phases of gas - oil – water are separated in treatment plants (free water knockouts, separators, production plants). After dehydration, associated gas is immediately ready for sale. Crude oil is stored in tanks and transported to the refinery in pipelines or railway tanks. The filtered water is re-injected into the reservoir.