After gas production ends, the decommissioning phase follows. When all connected gas fields have been produced empty, the wells are shut down. The dismantling of the installations present depends on the regulations and insights then in force. For this purpose, ONE-Dyas first writes a work plan that must be approved by the State Supervision of Mines. ONE-Dyas has experience in dismantling platforms. For example, ONE-Dyas removed satellite platform P11-E from the North Sea in autumn 2023.
There are two possibilities for closing the wells:
- suspend – the borehole is closed off with a valve.
- abandonment – putting mechanical and cement plugs at various heights in the borehole. Then the plugs and the conductor are cut off and removed 6 metres below the seabed. This ensures that no fishing gear can get stuck behind them.