The Norwegian Oil Industry Association estimates that more than 700 offshore workers have called a work action out of frustration with the association's position on pensions.
Statoil said the work stoppage led it to close four installations on the Norwegian continental shelf.
NOIC estimates the strike would cost around $25 million per day. Jan Hodneland, chief negotiator for the association, said the impact of the strike is far greater than unions had anticipated.
"Since personnel at the field center are on strike, transport of oil and gas from the surrounding platforms must also cease," he said in a statement.
The strike comes as the Norwegian Ministry of Petroleum and Energy had a licensing round for 72 blocks in the Barents Sea and 14 blocks in the Norwegian Sea.
"Together with improved recovery from existing fields, development of discoveries and opening new area, further exploration of open area is one of the main elements in the Government's work to achieve such a development and thus create further growth and secure jobs across the nation," Norwegian Energy Minister Ola Borten Moe said in a statement.