Decommissioning

Once all the oil and gas has been extracted, the wells and facilities will all be decommissioned. Approval is needed to retire a production facility through the marine (EEZ) or resource consenting process (RMA) depending on whether the structure is in territorial or EEZ waters. ⁴⁸⁶¹ This can involve plugging the well with cement and the dismantling and removal of equipment, plant and machinery. The wells must be plugged according to the health and safety regulations and in accordance with good oil field practise. ⁴⁸⁶⁰ All New Zealand’s offshore fields remain in production so decommissioning is yet to take place in our marine environment. In 2018, decommissioning is becoming a "looming" issue as some offshore fields may soon cease production. 

Prior to decommissioning, surveys are usually undertaken to map the location and quantity of debris, pipelines, power cables and natural marine environments. Post decommissioning surveys can identify any debris left behind during the removal process and confirm any environmental damage. Remote underwater vehicles and divers can be used to remove any debris and to ensure the area is free from any of the operational equipment.

Abandonment of oil rig infrastructure has become a major issue in the North Sea where there are many fields reaching the end of their producing phase. Best practice is to remove as much of the infrastructure as safely as possible. Another option being investigated is the storage of CO₂, where some of the existing infrastructure of depleted offshore oil and gas fields might be used for CO₂ sequestration after adaptation. ²¹⁷⁹

Last updated at 3:09PM on February 11, 2018