ConocoPhillips, the third largest oil and gas company in the US, has reported a 13% fall in fourth-quarter profits after problems at the firm.
Falling prices have dented profits
Production in the Alaska region was hit by transport delays and unanticipated maintenance at a North Sea oil field also hit output, the firm said.
The firm posted net profit of $3.2bn (£1.58bn) for the three months to December, down from $3.68bn in 2005.
Sales fell 19% to $42.54bn from $52.7bn in the same period a year ago.
ConocoPhillips' chief executive Jim Mulva said the company "continued to experience operational challenges".
Earnings at its exploration and production business and at its refining operations all slipped year-on-year.
Daily oil production rose to 2.05 million barrels from 1.59 million in the last three months of 2005, but the fall in the price of oil from the highs of mid-July hit revenues.