Gas exports from Statoil's Troll and Sleipner developments were higher than planned last year, while oil production from its fields off Norway fell.
Daily oil output from Norwegian offshore installations operated by the group averaged 1.4 million barrels, 8.7 per cent below the planned level.
"This shortfall reflects a faster-than-expected decline in production on our major Gullfaks and Statfjord fields," says Geir Pettersen, senior vice president for production operations.
"In addition, we've also faced a number of challenges on our new fields."
He notes that the Ã…sgard A production ship in the Norwegian Sea first came on stream last May, six months behind schedule. However, the vessel reached plateau output soon afterwards.
The Norne field further north was burdened with reservoir problems, but also achieved plateau production towards the end of 1999. It set an output record of 220,000 barrels per day in early December.
Veslefrikk's North Sea installations went through a major overhaul and modification, and also faced drilling challenges.
On the other hand, oil and condensate production from Heidrun in the Norwegian Sea and the Sleipner fields in the North Sea was higher than expected.
Total oil production on the Norwegian continental shelf declined to an average of 2.9 million barrels per day in 1999, while annual gas output rose from 43.6 billion cubic metres in 1998 to 47.4 billion.
Troll Gas and the Sleipner fields were the largest contributors to this increase.
Bad weather in January forced some of Statoil's fields to suspend production. As a result, Mr Pettersen reports, the decision by the Norwegian authorities to continue their self-imposed production curbs during the first quarter will have no effect on Statoil's operations.