Discovered in the early 1980s, production at Mariner was delayed because of technological limitations in extracting the denser type of oil. Statoil said it was bringing its experience in Canada and elsewhere to Mariner to facilitate heavy oil development.
The British government gave its consent to Statoil in February. The government expects the field to eventually produce around 55,000 barrels of oil per day, about 5 percent of the country's current production.
Statoil Vice President for International Production Lars Christian Bacher said Mariner's development is the largest of its kind in more than a decade.
Statoil said Tuesday it expects to start production from the field by 2017. Mariner is expected to hold more than 250 million barrels of oil. The energy company said the field should peak for three years beginning 2017 at 55,000 bpd.
The British government said the project represents a $7.1 billion vote of confidence from Statoil in the future of the country's oil and gas sector.