Statoil said the Shetland Group and the Lista Formation are younger and slightly shallower deposits, compared to the deposits of the Brent Group, where the Gullfaks main reservoirs are to be found.
According to the energy company, it was known for a long time that Shetland Group / Lista Formation in the Gullfaks licence hold considerable hydrocarbons, but they could not be developed due to poor reservoir qualities.
Statoil carried out well tests at production well 34/10-A-8, which currently provides a high and stable production of 7,500 barrels/day. The well has produced about one million barrels since December 2012.
The discovery is anticipated to contain a range of 40-150 million recoverable barrels of oil equivalent, based on preliminary estimation made after interpretation, modelling, formation testing and sampling.
Statoil and its partner are currently carrying out data gathering and studies to clarify the potential and further development of these resources.
Statoil Development and Production Norway executive vice president Øystein Michelsen said the new discovery at Gullfaks will provide new volumes and yield high-value production in a short time, while promising perspectives for the field and the installations.
"This is a result of Statoil's strategy for revitalisation of the Norwegian continental shelf," Michelsen added.
The Gullfaks field, which is situated in the Tampen area in the northern North Sea, came on stream on 22 December 1986.
The field development involved three permanent installations, which have produced more than 2.4 billion barrels of oil and more than 56 billion cubic metres of gas.
Statoil is the operator of the Gullfaks field, holding 70% interest, while its partner Petoro holds the remaining 30% interest.
Image: Gullfaks is expected to contain a range of 40-150 million recoverable barrels of oil equivalent. Photo courtesy of Statoil.