Privately-owned Greenergy announced that it had increased its stake in the project, built on the site of the former Coryton refinery, after acquiring Dutch rival Vopak's 33.3 percent stake. Royal Dutch Shell remains the second partner in the project.

The Thames Oilport tank field will have an initial capacity of 175,000 cubic metres, used mostly for storing diesel to supply the London region, and will gradually expand to become Britain's largest oil products terminal, Greenergy CEO Andrew Owens told Reuters.

The collapse in oil prices since June 2014 as a result of rising global supplies has made storage a highly lucrative business, attracting investment funds globally, as traders and refiners opt to store crude and oil products until prices recover - a market structure known as contango.

While the Coryton project had a bumpy path since its start three years ago, with partners scrapping an initial plan for a larger terminal than the current one, the contango has been a catalyst for its development in recent months, Owens said.

"The contango we've got at the moment is very much helping us to get momentum at Thames Oilport," Owens said, adding that it "allows you to do things on a phased and more slow motion basis because the contango is helping you pay for the capital".

Demolition of the former refinery infrastructure is underway to clear up land ahead of its expected sale in the first half of 2016, Greenergy said in a statement.

NAVIGATOR

At the same time, Greenergy created a partnership with Macquarie Capital, the investment unit of Macquarie Group to acquire Vopak's remaining UK assets as well as Greenergy's North Tees storage assets in Teeside.

The partnership, Navigator, is a "stepping stone" for Greenergy, allowing it to access capital for further growth over the next decade. "Navigator creates a financial structure which enables us to continue and accelerate our investments in oil industry terminal infrastructure," Owens said.

Vopak said the divestment of its UK business amounts to 335 million pounds.

Greenergy, Britain's largest oil storage operator, also has operations in Canada, the United States and Brazil.

CLOSURE SLOWDOWN

Owens said the golden days for oil refinery profits over the past year, a result of low crude prices and a sharp rise in demand for products, will slow closures in Europe that most had expected to continue steadily through to the end of the decade.

"They've been astounding – that's the only word for it," he said of the margins this year, adding that "the refineries have made so much money that they can sit on that for a while and burn it away for a bit."

Refinery capacity of some 2 million barrels has closed in Europe since 2009, as pressure from state-of-the-art new units in the Middle East and Asia squeezed European refiners' profits.

But the global excess of oil that forced crude prices to 10-year lows also helped oil companies squeeze more money this year from Europe's comparatively smaller, older refineries.

Capacity closures also allowed Britain to more than triple net imports of petroleum products last year.

"At the moment, the UK is still short capacity," Owens said. "(But) when the Thames Oilport is up and running, that's more than enough capacity."

(Reporting by Ron Bousso and Libby George; Editing by Mark Heinrich)

By Ron Bousso and Libby George

Stocks treated in this article : VOPAK, Macquarie Group Ltd