Oil production in the sensitive tideland eco-system
Germany's biggest oil reservoir and most productive oil field is located in the Mittelplate tideland area, about 8 km from the North Sea coast. As this is a sensitive ecosystem, a special man-made drilling and production island was developed and built. The deployment of sophisticated technology, minimization of the environmental impact, multiple safety features in all phases of operation and the commissioning of experienced and responsible highly skilled specialists ensure that an optimum safety package is in place, guaranteeing reliable environmental protection in the course of oil production on the Mittelplate Island. The safety and environmental protection measures applied have set standards as the best available technology and enjoy a high international reputation.
Environmental protection through impenetrable defenses
The basic principle behind Mittelplate Drilling and Production Island is reliable, impenetrable defenses – externally against the forces of nature and internally to protect the environment.
For this reason, the 70 x 95 meter Drilling and Production Island was constructed on Mittelplate’s sandy tidelands as a compact, leak-proof steel-and-concrete basin with sheet pile walls of up to 11 meters in height protecting the most exposed side against the elements. Nothing (except rain and spray) can get in, nothing (uncontrolled) can get out, and nothing can seep into the seabed. Additional protection is provided by a scour protection to protect this artificial island from erosion.
Designed on the basis of extremely thorough hydrographic, water-flow and meteorological studies, the island was constructed to be as robust as humanly possible.
No harm to the North Sea
The principle of impenetrable defenses extends to everything that might possibly prove harmful to the environment.
- Nothing leaves the island uncontrolled.
- Waste water from the residential quarters and kitchens is purified in the island's own treatment plant, collected in tanks and then disposed of in a sanitary landfill in the same way as solid waste.
- The water produced with the crude is removed and re-injected to the reservoir - again in an absolutely closed system.
- The extremely robust basin-like construction has yet another advantage. In the event of an accident, the impermeable surface of the island, which is sealed by the specially developed concrete and sheet pile walls, could hold far more crude than is stored on the island at any one time. What’s more, the extensive system of pipe and cable ducts and the large rig cellars are all oil-tight, too.
Closed disposal system for drilling operations
A closed disposal system ensures that none of the wells can pollute the North Sea. The rig cellar and boreholes are located above the sealed concrete basin. The drilling mud carries sand and rock cuttings to the surface. However, they are not discharged into the sea, as is normal practice, but taken ashore in containers for a suitable treatment.
Monitoring and controlling all operations
Production and processing operations are controlled and monitored around the clock by specialist staff with the help of sophisticated control facilities and computers. There are multiple safeguards against possible risks. If, for example, there are any problems with production, the pumps automatically shut off. 90 meters below the surface, the wells are secured by quick-acting safety valves that are kept open hydraulically at a pressure of 130 bar during normal operations. If pressure falls, the valves automatically shut. More shut-off valves at the wellhead are an additional safety reserve against the risk of pressure rising or falling.
Emission protection measures
Since all the process tanks are linked to a closed system with vapor recovery pipes, emissions can be effectively avoided at Mittelplate.
The associated gas produced with the crude is separated and used to generate heat and power in two soundproof gas turbines.
Environmental monitoring
In the course of the development of the Mittelplate oil field, the production joint venture commissioned independent research institutions to perform accompanying scientific studies to examine and assess the impact of oil production on the sensitive ecosystem. These include biological studies focusing on benthos, fish and birds, as well as marine geomorphology and sedimentology studies in selected areas.
