British oil and gas company Hurricane Energy started up its Lancaster field west of Scotland's Shetland Islands, it said on Monday, pushing its shares up 6 percent to a seven-week high.
Hurricane specializes in recovering oil from fractures in hard and brittle rock known as fractured basement reservoirs, which some see as a risky way to obtain crude.
Hurricane's floating production, storage and offloading (FPSO) vessel was connected to the group's North Sea Lancaster oilfield in March after a technical hiccup in January.
Hurricane expects the field - which it started up on Saturday - to produce at a plateau of 17,000 barrels of oil per day.
Hurricane will analyse data from each well individually and reiterated it would reach so-called 'first oil' - or three days of simultaneous flow from both wells at the field - by the end of June.
There is no fractured basin field in production in Britain at present. Lundin Petroleum extracts oil from a fractured reservoir in the Norwegian North Sea.
Together with its Greater Warwick Area (GWA) project, Hurricane aims to add net reserves of 750 million barrels to its portfolio.
(Reporting by Shadia Nasralla, editing by Deepa Babington)