Deployment of state-of-the-art drilling technology to develop oil reservoirs
The Wadden Sea Tidelands National Park is a particularly sensitive and protected area. With many innovations we have steadily further developed our drilling technology and has optimized this in harmony with the natural environment.
A total of 20 wells produce from the oil field at a depth of up to 3,000 metres. The unique design of the drilling and production island reduces the effects on the Wadden Sea to a minimum.
Simultaneous on- and offshore development
Since the year 2000 we have also been producing oil from the Dieksand Land Station. Here the extended-reach drillings are diverted over a very long distance of up to 9,275 metres. Four kilometres of this distance is accounted for by the Büsum salt dome. These drillings represent top initiatives on a worldwide scale. The simultaneous offshore and onshore development enables optimum production of the crude oil reservoir.
High-performance drilling unit
In 2005 the T-150 drilling unit – one of the most modern in Europe – went into operation on Mittelplate. Some 50 million euros were invested in the new drilling unit, as a means of further improving environmentally friendly production in the Wadden Sea. The T-150 is electrically driven and has an overall performance of 10,000 hp. This emission-free drive is particularly quiet-running and is ideal for deployment in the Wadden Sea Tidelands National Park. Drillings with a length of up to 8,000 metres can thereby tap the oil reservoirs without difficulty.
The steel frame of the 70 metre high derrick at Mittelplate is encased in high-grade-steel trapezoid sheeting. This casing protects both the employees and the drilling unit against wind and weather. The sheathing also notably decreases noise and light emissions and so further reduces disturbances to the environment.
To exploit the Mittelplate reservoir, we use the latest technologies such as multilateral wells. Instead of drilling several separate wells, multilateral wells only require a single well which accommodates multiple production lines. In an already completed well, a hole is cut in the casing as a starting point for lateral branches. Depending on the type of reservoir and the type of junctions put in place, it is possible to drill several lateral branches extending from a parent well – this is referred to as a “multilateral well”. This technique allows multiple targets within a reservoir to be tapped through a single well.
An advantage is that up on the surface, only one borehole is needed to accommodate multiple production lines in the rig cellar on the Mittelplate Drilling and Production Island, which saves valuable space. In addition it also minimises the environmental impact.
Before the crude can enter the production line, it needs to be perforated: this is achieved by shooting small holes into the pipe, the cement casing and the surrounding rock. These holes allow the crude to flow into the production line. The longer the section opened via the perforation, where crude can enter the production line, the higher the production.
Up to now, four multilateral wells were drilled to tap the Mittelplate deposit. Each time multilateral wells with two production strings were used, so-called dual lateral wells. The dual lateral well A24 of 2010 was the first multilateral well drilled in Germany so far. In 2015, we were able to finish the dual lateral well A26 with a parent well of 6,100 metres in length and a lateral branch of 1,500 metres in length. It took ten months to complete this technically challenging well, and costs were around the middle of the double-digit million range. The length of the perforation along the production line was a record-breaking 2,461 metres.