Statoil said that this year it expected to produce 1.9 million barrels of oil equivalent per day (mboe/d), down from its previous estimate of between 1.925 and 1.975 mboe/d.
"Extensive planned maintenance activities throughout the third quarter have affected both our oil and gas production significantly," chief executive Helge Lund said in the earnings report.
During the July-September period this year, Statoil said its production plummeted 17 per cent year-on-year, to 1.552 mboe/d.
Following the news, Statoil saw its share price shed 4.10 per cent at the opening of a slightly negative Oslo stock exchange.
"The production is not high and it is even more disappointing to see that they are lowering their full-year forecasts," Carl Christian Bachke, an analyst with RS Platou Markets, told TDN Finans.
The company meanwhile said the production increase would be limited in 2011 and that its production forecasts for 2012 remained unchanged at between 2.06 and 2.16 mboe/d.
The company also said it had decided to temporarily reduce production in two North Sea fields, Gullfaks South and Kvitebjoern, to keep the reservoir pressure at a sufficient level to allow it to safely drill additional wells.
Despite the production lag, Statoil saw its net profit nearly double in the third quarter to 13.8 billion kroner (1.67 billion euros, $2.36 billion), up from 7.4 billion a year earlier, largely due to a hike in oil and gas prices and lighter taxation.
During the three-month period, oil prices swelled 14 per cent and gas prices grew eight per cent, the company said.
Statoil's net operating income during the quarter meanwhile inched down to 28.2 billion kroner from 28.3 billion a year earlier, on sales up 2.7 per cent at 125.8 billion.
While the company's net profit easily beat analyst expectations of 9.4 billion kroner, according to a poll by Dow Jones Newswires, its operating income missed the mark.
The expected production drop will impact extraction costs, pushing them up to between 36 and 37 kroner per barrel from a previous estimate of between 35 and 36 kroner, Statoil said.
Last Friday, the company put 46 per cent of its Statoil Fuel and Retail (SFR) division of service stations up for trading on the Oslo stock exchange, an initial public offering (IPO) that raised 5.38 billion kroner.