What to do with ageing oil and gas platforms – and why it matters

Oil and gas platforms are immense – and so is the challenge of decommissioning them – withdrawing them from use.

There are 12,000 offshore oil and gas platforms around the world and many of them are nearing the end of their lives.

Decommissioning these structures safely and sustainably is tough – but essential.

Oil and gas platforms that have reached the end of their lives can be completely or partially removed from the ocean. They can also be moved elsewhere, abandoned in the deep sea or toppled and left on the sea floor, explain marine experts writing in the science journal, Nature.

The North Sea has more than 1,500 platforms and installations with an average age of 25 years.

Another 1,500 oil and gas platforms are more than 30 years old in the Gulf of Mexico.

And in the Asia–Pacific region, more than 2,500 platforms will need to be decommissioned in the next decade, the report says.

Dismantling and recycling end-of-life oil and gas platforms is one option for decommissioning.

An example is the Brent Delta platform, one of four installations from the Brent oil and gas field northeast of the Shetland Islands in the North Sea.

When this ceased production after nearly 35 years, its topside – the part of the platform above the waterline – was lifted out of the sea and shipped to a specialist decommissioning company in Teesside in the United Kingdom for dismantling.

An impressive 97% of the platform, including large amounts of steel, was reused or recycled.

When the subsea parts of decommissioned oil and gas platforms are left in the sea, they can provide habitats for marine life like fish, corals, sponges, seals and whales.

Wildlife charity The Scottish Wildlife Trust says there can be ecological benefits to leaving oil rigs in place.

Researchers writing in the journal Ocean & Coastal Management argue that completely removing decommissioned oil and gas platforms would kill fish and destroy invertebrates, which include species such as molluscs and jellyfish.

In Malaysia, a decommissioned oil rig has been converted into a diving resort.

And more than 600 rigs in the Gulf of Mexico have been repurposed in similar ways as man-made reefs for diving, recreational fishing and other water sports, the Nature report notes.

This approach, where the underwater substructure of the platform is left under the sea, is known as “rigs-to-reefs” and has been used to decommission oil and gas platforms since the 1980s.

It can produce almost seven times less air-polluting emissions than completely removing the rig, the report suggests. However, opponents are sceptical and say abandoned platforms can leave harmful chemicals in the ocean.

Decommissioned oil and gas platforms can be repurposed into green energy hubs to help the world transition to net zero emissions, some reports have suggested. This could include using offshore rigs for carbon capture and storage or storing and transporting hydrogen, a type of sustainable fuel that doesn’t emit carbon when it’s burned.

A report by government and industry partners in the United Kingdom in 2019 suggested using legacy oil platforms to produce green hydrogen, which is generated using renewable energy.

Some existing oil and gas platforms and pipelines could be used in these green energy hubs, the report suggests.

In its Fostering an Effective Energy Transition 2023 report, the World Economic Forum ranks 120 countries – including oil and gas-producing economies – on their current energy systems and transition to clean, sustainable sources of energy.

The report outlines actions by countries and industries. The United States, for example, has introduced funding for energy transition improvements including $4.7 billion to reduce methane emissions from orphaned oil and gas wells.

While, in Canada, oil and gas companies are investing in carbon capture and storage technology. And, in the United Arab Emirates, the cost of renewable energy has fallen rapidly in recent years, making it increasingly competitive with fossil fuels.

The “march of sustainable energy” has kept pace through a period of extreme volatility, the Forum says. And last year, for the first time, investments in low-carbon energy technologies surpassed a record $1 trillion.