Oil rigs may end their days as valuable artificial reefs

Materials World magazine
13 Jul 2018

Researchers encourage environmental authorities across the globe to rethink the idea of removing oil rigs, wind turbines, and other installations in the sea when they are worn out.

A submerged camera at an old worn out oil rig shows an extensive life of flatfish, cod, and bottom fauna in all its forms. A life usually not seen in these parts of the North Sea, where the oil rig awaits decommissioning after 25 years' of service in pumping oil and gas from the ground.

'We also see many more porpoises around oil rigs than in the surrounding sea,’ said Senior Researcher Jonas Teilmann from Aarhus University, who has been involved in the studies that have just been published in the international journal Frontiers in Ecology and the Environment.

Artificial reefs form oases in the sea

An oil rig or other artificial installations are typically present for 20–30 years in the sea. Through this period, the tubes, bars, concrete bricks, and much more turn into beneficial substrate for adhering plants and animals. And this rich environment attracts fish and mammals.

Internationally, it has been decided that that all artificial installations in the sea must be removed when they are no longer in use. But, now almost 30 international researchers say that this decision perhaps should be reconsidered.

'In, for example, the North Sea, an old oil rig will have the same function as a natural stone reef,' Teilmann said.

And stone reefs are in short supply as stones have been removed and used for, among other things, pier construction or been destroyed and spread due to use of heavy trawls.

Avoid trawling

'We have observed a significantly increased biodiversity around the old facilities and encourage the authorities to consider, in each individual case, whether an exemption from the demand for removal can be granted. When making the assessment, the environmental conditions must, of course, be of sufficient quality,' said Teilmann.

Around the world, there are more than 7,500 oil and gas platforms and between 10,000 and 20,000 wind turbines that need to be removed at some point. It is estimated that it will cost up to €100bln to remove these installations.

Click here to read the full study, Environmental benefits of leaving offshore infrastructure in the ocean.