Hurricane Energy said on Friday it tripled its estimate of recoverable oil from its Lancaster field in the North Sea.

The announcement came a few days after Hurricane announced an oil discovery in the Halifax well West of Shetland which it believes could be Britain’s largest undeveloped oil find.

In a presentation to investors, Hurricane said it had upgraded its recoverable resource estimate for the Lancaster field to 593 million barrels from an earlier estimate of 200 million.

Output from Lancaster is expected to start in the first half of 2019, with a daily production rate of 17,000 barrels expected soon after.

The update on Lancaster means Hurricane’s resources from its prospective fields could come close to 1 billion barrels, according to analysts at Panmure Gordon.

On March 27, Hurricane confirmed it had made an important oil discovery west of Shetland, calling the find “the largest undeveloped discovery on the UK Continental Shelf.”

Hurricane announced the completion of the Halifax Well operations, saying “the well is an oil discovery with initial data analysis indicating Halifax is linked to the Lancaster field forming a single large hydrocarbon accumulation.”