Completion of the well
If the presence of hydrocarbons is confirmed then a production casing, similar to the surface and intermediate casing installed during the drilling process, is cemented in place right to the base of the well.
Within the well, production pipework, controls and safety barriers are installed and on the surface, a valve block (known as a “christmas tree”) caps the well. In some cases, if the necessary production pipework and controls are temporarily unavailable, the well is suspended with plugs and a temporary well head at surface level to provide the seal. All this enables the necessary integrity for the well to assure its safety and prevent any escape of hydrocarbons. The drilling rig is then disassembled and moved off the site.
In the event that the well is unsuccessful, it is sealed with cement plugs and the surface casing is cut to below the ground level. The rig is disassembled and moved off-site and then the site itself is restored to its original state.
The "christmas tree" is installed when the well is completed
(Click to zoom in)