Royal Dutch Shell RDS.A -1.63% PLC spent billions of dollars developing one of the world’s most challenging energy projects, a floating gas terminal five football fields long. The coronavirus pandemic is posing a new problem: How to get workers to safely start it back up.

After years of delays, cost overruns, technical problems and safety concerns, Shell began exporting natural gas from the enormous vessel, known as Prelude, last year off the coast of Australia. But production was halted in February because of an electrical fault. Efforts to restart are now being slowed by social-distancing requirements, the company said.

The work “continues to be impacted by measures in place to reduce the risk of Covid-19 spread offshore,” Shell said in an emailed statement. It declined to say when Prelude would resume exporting gas.

Floating Giant

Shell’s Prelude gas terminal is the largest facility of its kind ever built.

One World

Trade Center

1,776 ft.

Prelude vessel

1,601 ft.

Empire State

Building

1,250 ft.

Eiffel

Tower

1,063 ft.

Statue of Liberty

305 ft.

Sources: Council on Tall Buildings and Urban Habitat (One World Trade Center, Empire State Buildling); the company (Prelude); Skyscraper Center (Eiffel Tower); National Park Service (Statue of Liberty)

Prelude’s plight highlights how the coronavirus has complicated operations at some of the world’s largest energy projects. Work camps and oil-and-gas platforms in remote locations where staff live in close quarters are vulnerable to the spread of the virus, and there have been outbreaks this year at facilities in Kazakhstan, Mozambique and offshore in the Gulf of Mexico. It also illustrates how the destruction in energy demand caused by coronavirus lockdowns, and resulting lower prices, is challenging the economics of megaprojects that companies approved when oil and gas prices were higher.

The largest facility of its kind ever built, Prelude was supposed to be the first of several megavessels Shell planned in an effort to tap hard-to-reach gas deposits out at sea. But the company quickly decided Prelude would be a one-off as costs escalated, according to a person who worked on the project. Construction wound up costing $15 billion, a person familiar with the matter said.

Some analysts estimate the overall costs were higher. Consulting firm Wood Mackenzie pegged the likely cost at $17 billion, which it estimates is around $5 billion more than Shell had initially budgeted in 2011 when it was approved. “When Shell sanctioned Prelude the oil price was above $100 a barrel; the world was very different,” said Daniel Toleman, an analyst at Wood Mackenzie, adding that the shale boom and 2014 oil-price crash changed companies’ thirst for new oil and gas projects. Benchmark Brent crude traded at around $44 a barrel on Friday.