Safety and environmental protection
The development of the Mittelplate oil reservoir requires particularly safe and environmentally compatible technical solutions. Encroachment on the sensitive ecosystem has to be reduced to a minimum in all of the work undertaken. This target is achieved through continuous optimisation of drilling and production operations.
The combination of state-of-the-art technology, highly-qualified employees and sophisticated monitoring and safety systems has enabled trouble-free operation of the Mittelplate Drilling and Production Island since 1987.
The safety concept of Mittelplate
- The Mittelplate Drilling and Production Island is securely anchored on a sandbank. It cannot sink.
- Safety valves, both below and above ground, securely close the borehole in cases of emergency.
- Many fire and gas alarms are installed on the island and transmit their data to a headquarters control room which is permanently manned.
- Mittelplate is constructed like a liquid-retarding steel and concrete basin. Nothing can escape from the island unchecked.
- The comprehensive waste disposal system ensures that the North Sea and the Wadden Sea remain uncontaminated.
- There are emergency plans at the ready, in case of accidents. And employees are optimally prepared for crisis situations through regular safety training and instruction.
The seal-off principle
The basic principles adopted by Mittelplate are protection of the island against the natural elements on the one hand, and sealing off from the outside world, for protection of the environment, on the other. That's why the 70 x 95-metre drilling and production island was designed as a liquid-retarding steel-and-concrete basin on the sand flats. The external sheet pile walls are eleven metres high. Nothing leaves the platform unchecked. Even leaks are prevented. And nothing can enter from outside except for rain and spray water. The construction, which was chosen following thorough hydrographic, current-flow and meteorological investigations, provides optimum stability. And the entire construction is permanently protected against erosion.
Pipeline connection replaces shipping traffic
Since 2005, oil has no longer been transferred by ship, but has been pumped through a pipeline from Mittelplate to the processing facilities of the Dieksand Land Station. We invested more than 100 million euros in the construction of the pipeline and the extension of the processing facilities. The technically demanding pipeline-laying concept was developed by geologists, engineers and environmental protection experts and was then realised in keeping with the strict nature conservation stipulations. The aim here was not only to ensure a constant flow rate of oil transportation that was independent of weather and tidal conditions, but also to secure considerable overall ecological utilisation of the project. With the putting into operation of the pipeline there are some 2,000 ship transfers fewer each year. And the transportation of the oil through the pipeline is safer and more environmentally friendly.
Waste disposal system
The drilling and production island has a completely enclosed waste-disposal cycle. All waste products – from cuttings to eggshells – are brought ashore in containers where they are passed on to specialist disposal services. The waste water from the accommodation and kitchen areas is cleansed in a self-operated purification plant and then disposed of on land, as in the case of solid waste. Even rainwater and spray water are collected and cleansed on the island.
Supervision of operations
Drilling and production operations are supervised around the clock using ultramodern control and measurement systems. The technology deployed has several backup systems. If one system fails, another takes over immediately.
Should irregularities appear in the production process, the oil pumps switch off automatically and the subsurface safety valve closes the borehole. Further shutoff valves on the well head provide additional safety against vacuum and overpressure.
The Wadden Sea alters continuously with a natural dynamic of its own. Scour protection reinforces the Mittelplate island with stones and water-resistant mortar and so provides reliable protection against erosion and the degradation of the ground. Should natural changes in the tidelands require an extension of the scour protection. This can be undertaken in several stages, whereby the scour protection can be deepened in the process. All work on the external reinforcements complies with the environmental protection stipulations and are monitored by the supervisory authorities.
Protection of the tidelands
The massive sump design of Mittelplate was planned and erected in such a way that it can withstand extreme loads unscathed. However, it not only protects the plant installed there and the employees, but also the tidelands. In the event of an accident it can even collect more oil than is contained on the island.
The reservoir water extracted along with the crude oil is pumped via the pipeline to the Dieksand Land Station where it is separated from the oil and cleansed. Then it is returned to the reservoir as part of this closed cycle. Since all process tanks gas transfer lines are connected to a closed system, emissions can be avoided with certainty.
It is our intention to reduce light emissions so that birds of passage are disturbed as little as possible on their journey through Wadden Sea National Park. The Mittelplate lighting concept is therefore such that as little light as possible escapes, while at the same time ensuring that the workplace is sufficiently well lit and is thus more safe.
An optimised lighting concept was prepared and implemented. The putting into operation of light-controlling movement detectors and of light-guidance sheeting, as well as a decrease in the number of light sources, has reduced light emissions considerably.
Before-and-after comparison of the lighting on Mittelplate
To find out whether the measures adopted had been successful, we prepared a before-and-after photo documentation. In each case our employees took the photos with the new moon, so that the results would not be falsified by other light sources. Even at a glance, a notable improvement can be recognised.
“The safety of staff has top priority – personal security always comes before protection of systems and technology.” The escape routes (gangways, corridors, ramps and stairs) are built in such a way that workers from all areas of the Mittelplate Island are able to reach the gas-tight collecting space below the living quarters with its own separate oxygen supply swiftly and safely. A new pier with a large pontoon and a stable gangway without stairsalso enables evacuation by boat. At low tide there is an alternative escape route over the southern footbridge which leads to the scour protection outside. During high tide it is possbile to use ten life rafts. In case of need there is also a helicopter deck which makes rescue by helicopter possible.
We recognise our responsibility towards the unique natural area of the tidelands and initiates extensive measures aimed at protecting the environment. These are accompanied by related studies undertaken by independent research institutes and engineering offices, to test their effectiveness. Detailed analyses have been and are being carried out to investigate the potential effects of the drilling and excavation activities on plant and animal life.
Proven environmental compatibility
The studies conducted into the influence of oil production on the ecosystem of the tidelands come to the conclusion that, after the construction of the island, no negative influence on the tideland region has taken place. The Mittelplate project has proven over many years that the ecology of the tidelands is compatible with production of the important raw material of crude oil.