Situated roughly halfway between Edinburgh and Glasgow on the Firth of Forth, the 700-hectare petrochemical complex is a vital hub of UK oil production. Should Scotland vote for independence, it will be one of the new government's key assets.
According to the industry, there are between 15 and 24 billion barrels of recoverable oil and gas left under the North Sea. About 42bn barrels have been extracted since production began there in 1967.
Because prices have risen, 24bn barrels could be worth £1.5 trillion – more than the value of all the oil and gas extracted so far. "That gives us one of the best financial safety nets of any country in the world," the Scottish government says.
If the UK's Trident nuclear submarine base moves from the river Clyde after independence – as Scottish nationalists say it must – then prospecting off the west coast could begin too. It is currently banned in case it interferes with naval operations there.