After a successful drilling operation, Deutsche Erdoel takes a series of other safety measures in production. The cased borehole is specially prepared for production. The focus is on safely managing the pressures and the respective produced medium. To guarantee this the following safety components are employed.
Packer secures the production string
Once a well has been completed and cleaned, the installation of the production string begins. Individual casings around 9.5 metres in length are screwed together to create a long casing string. At the end of this string there is a sealing element, known as the packer. This is comprised of a tube, over which an extremely durable rubber cuff is drawn. The packer is fed into the production string and the cuff is then pressed against the inner wall of the production string to create a gas-proof seal. Protective fluids are then introduced via the packer tube into the cavity that has been created.
Subsurface safety valve closes automatically and safely
In the case of wells in which oil and gas flow naturally because of the pressure conditions, subsurface safety valves are installed at a depth of 50 to 90 metres. These are cylindrical in form and are equipped with ball valves. In normal operation, the valve is held open with the aid of hydraulic pressure. If this pressure falls, the valve closes automatically. The safety valve can also be closed manually at any time from the continuously manned control room. This means that the well can always be securely closed under exceptional circumstances.
Wellhead assembly protects production
All the casings as well as the production string are caught and sealed in a flange. This is topped by the wellhead assembly, the so called christmas tree, which performs the same function in production as the blow-out preventer when drilling. It is equipped with several gate valves and it serves as a well plug for a successful drilling project. If the christmas tree or any connected pipes are damaged, either a contact pressure gauge or a pressure drop in the control lines causes the well to be automatically shut off and secured.