Mittelplate/Dieksand

Location and Geology

The Mittelplate oil field is situated on the southern edge of the Schleswig-Holstein Wadden Sea National Park, approximately 7 kilometers off the coast of Germany. The field is embedded in the Dogger sandstone formation, which was identified as oil-bearing through the discovery well Mittelplate 1 in 1981.

Reserves and Production

The initial reserves were estimated at 75 million tonnes of crude oil, but subsequent redevelopments have increased the estimated reserves to over 100 million tonnes, with commercially recoverable reserves totaling around 40 million tonnes.

Infrastructure and Development

Mittelplate Island

The production is centered around an artificial drilling and production island built to withstand the harsh tidal, wave, and ice-flow conditions of the area. The island measures 70 meters by 95 meters and is protected by 11-meter-high sheet piling. It accommodates 18 wells (with slots for up to 44 wells), some of which are horizontal or deviated, reaching depths of up to 3,000 meters to tap the oil-bearing sandstone layers.

Land-Based Facility at Dieksand

As part of the redevelopment, a land-based facility was constructed at Dieksand. This facility allows for the drilling of extended-reach production wells, up to 3,000 meters long, to access the eastern part of the deposit. The program included several high-tech extended-reach wells, one of which cut through the Büsum salt diapir over a distance of 4 kilometers.

Pipelines

To enhance transportation capacity, two 7.5-kilometer stainless steel pipelines were laid from Friedrichskoog-Spitze through the mudflats and the Marner Plate to Mittelplate Island. One pipeline carries crude oil from the island, while the other serves as a return line for reservoir water, which is reinjected into the lower section of the oil reservoir in an ecologically neutral process. The pipelines were installed using horizontal drilling and pre-assembled sections.

Operational Details

Consortium and Operators

The Mittelplate Consortium consists of RWE Dea (now part of Wintershall Dea) as the operating company. Wintershall Dea is the primary operator of the field.

Production Capacity

The initial annual production was around 250,000 tonnes of crude oil, but after the major redevelopment in 2005, the production capacity increased to nearly 900,000 tonnes per year. Currently, over 2,700 tonnes of oil are transported ashore daily.

Living Quarters and Facilities

The redevelopment included new living quarters on Mittelplate Island, increasing the accommodation capacity from 69 to 96 people. The facilities include double cabins, offices, sanitary facilities, mess and kitchen facilities, a medical treatment room, social facilities, and enhanced safety systems.

Environmental Considerations

Given the sensitive ecological environment of the Wadden Sea National Park, the project has implemented environment-friendly offshore production strategies. The reinjection of reservoir water into the oil reservoir is an example of an ecologically neutral process.

Historical and Economic Context

The Mittelplate field came onstream in 1987 and underwent a significant €150 million redevelopment by the end of 2005. This redevelopment has been crucial in increasing production and transport capacity, making it a significant contributor to Germany's oil production.