Safety during drilling operations

One of the biggest risks when drilling is the uncontrolled escape of hydrocarbons from underground. Deutsche Erdoel employs the latest safety technology to deal with this potential risk. This includes three key components.

Drilling fluid equalises pressure

Gas and oil are to be found in rock pores far below the surface. Depending on the density of the rock and the depth, the pressures to be found there vary. To prevent the raw materials from rising through the borehole in an uncontrolled manner and escaping, drilling fluid is injected into the well through the drill string. The hydrostatic pressure of this drilling mud acts against the pore pressure and thus prevents any unwanted escape of raw materials.

Blow-out preventer securely seals the borehole

One key safety element when drilling to great depths is the blow-out preventer. This device uses shut-off valves mounted one on top of another, which operate independently of one another, and annular cuffs. These are fitted directly above the borehole, i.e. on the ground or on the seafloor. When required, the blow-out preventer encloses the drill-string and seals it off. Should a complete shut-off become necessary in an emergency, the shear jaws cut through the drill-string and seal off the borehole. The shut-off valves are powered by a hydraulic system and can be activated automatically or manually. Regular inspections and various tests on Deutsche Erdoel's blow-out preventers guarantee their trouble-free and safe deployment at any time.

Cementation seals and stabilises the casing segments

The casing protects the borehole in the long term from the surrounding rock strata. The casing segments, inserted inside one another like a telescope, are stabilised and sealed with cement. The cementation provides an indestructible, gas and oil-sealed connection. This prevents any uncontrolled escape of hydrocarbons, which can lead to damage and corrosion of the casing.

Example for a gas well casing and cementation in Lower Saxony, Germany

The cementation must be very durable, and for that reason it is individually adapted to each set of reservoir conditions. Measuring and monitoring systems continuously check that the cementation is still functional.