Oil is used in technologies that are essential for the achievement of the energy revolution – in insulation materials for power stations and pipelines, in solar cells and in wind turbines. In fact, around 45 per cent of the components in a wind turbine are made from oil-based or petrochemical products, and the blades would not turn at all without suitable lubrication. A wind turbine requires around 500 to 600 litres of high-quality lubricating oil every year to keep on turning. What’s more, former oil and gas wells are often suitable for the exploration of geothermal energy. Here, deep borehole heat exchangers are installed in boreholes no longer in use. In a continuous cycle, water is pumped into the deep subsurface, absorbs heat from the surrounding rocks and is returned to the surface, where the heat is extracted. Such systems are already in use in many regions of Germany for supplying heat to private homes and thermal spas.
Domestic oil production – a central driver of the economy
In Germany, domestic oil production of 2.4 million tonnes of crude oil produced in 2014 covered 2.7 per cent of domestic oil demand. Together with imports, domestic production ensures security of supply. Experts estimate that in 2035, one-half of global energy demand will continue to be met by oil and gas. At a national level, consumers, federal states, communities and the industrial segment all benefit from domestic production.
Oil and gas companies operating in Germany are important employers and drivers of local economies, and companies in the exploration and production sector employed 10,085 people in 2013 – more than ever before.
Seen on a global scale, the oil fields in RDG’s concessions are small, and the reserves they contain can only be exploited economically with innovative technologies. 3D seismic surveys are a powerful tool for the discovery and development of increasing numbers of new oilfields, and help to ensure that oil production will continue for decades to come.
Oil extraction technology: various methods, depending on the production phase
After completion of the drilling phase, the borehole is lined by the installation of a filter tube (casing) and a riser (tubing) in the reservoir formation. In the first phase of production, the oil ideally flows through the well to the surface without pumping on account of the natural pressure within the reservoir. When the pressure falls, it becomes necessary to use techniques such as gas lift. This involves injecting pressurised gas through the production tubing to reduce the hydrostatic pressure of the fluid column. The resulting reduction in bottom-hole pressure allows the reservoir liquids to enter the wellbore at a higher flow rate and rise to the surface without pumping. After this so-called ‘eruptive phase’, a range of pumping technologies can be employed, depending on the properties of the crude oil, its oil–gas content and the pressure conditions. If the oil-gas content is low and reservoir pressure is falling, the oil is transported to the surface by deep-well pumps. At the surface, the only visible sign of this is the pump jack, with its typical horse head counterweight on the end of a walking beam. For higher flow rates, electric submersible rotary pumps can be installed in the tubing.
Treatment – separation of gas, oil and water
In its state as it is brought to the surface, crude oil is not yet suitable for refining, and it must first undergo a number of processes to prepare it for transportation. Under favourable conditions, primary recovery of over 50 per cent can be achieved. However, in the case of insufficient reservoir pressure or extreme viscosity, the primary recovery rate may only be between five and fifteen per cent of the original reserves in place. After the crude oil has been extracted, the formation water and sand it is mixed with must be removed by treatment systems (separators, strippers and production tanks). The treated oil is then collected in tanks and transported by rail, road or pipeline to a refinery. Water separated from the oil is pumped back into the reservoir from which it originated.
Particularly in the case of oil production, an average of about 60 per cent of the reserves in place currently remain in the ground. For the future, RDG is conducting research into methods for further increasing the oil recovery rate with a view to making domestic crude oil available as an essential raw material for many decades to come.