Drilling

Drilling is the cutting process to create a borehole or well using a rotating drill bit to crush and grind rock. Rock cuttings from the base of the well are carried to the surface by drilling mud. The drill mud circulating through the hollow drilling string is emitted by jets at the drill bit and transports the cuttings to the surface in the annulus between the drilling string and the wall of the well. Sieves and cyclones filter out solid matter from the drill mud so that it can be stored in a tank and pumped back into the well.

RWE Dea's specialist team uses state-of-the-art technology to drill to depths of more than 5,000 metres. The diagram shows the various layers of rock the well has to pass through.