In a statement, operator StatoilHydro said activity had returned to normal on the Statfjord A platform and that a plug had been installed in the pipe to stop the leak.
"Organization on the platform is currently preparing to receive the evacuated personnel who will be transported back to Statfjord A this evening," it said on its web site.
Two people were exposed to gas during the incident but neither was seriously injured, said company spokesman Ola Morten Aanestad.
About 1.2 million liters (320,000 gallons) of water mixed with oil was discharged into the sea as a safety precaution during the operation.
The company said there was "a thin oil film around the Statfjord A platform and measures have been implemented to collect it," the company said. "Oil protection equipment and oil booms are being deployed."
StatoilHydro said work would continue throughout the evening to control the oil film.
Production was stopped immediately after the leak was detected, and is likely be shut down "for several days," the company said.
Aanestad said there had been a small risk that gas released during the oil leak would ignite, so 156 of the 217 people on the platform were evacuated Saturday morning. Sixty-one emergency workers had remained on Statfjord A, he said.
StatoilHydro said the leak occurred during maintenance work on a pipe in one of the platform's three shafts and that oil had leaked from one of several storage cells. The storage cells hold 1.3 million barrels of oil, the company said.
The platform began production in 1979 and is one of three being operated by StatoilHydro in the Statfjord field, located about 125 miles (200 kilometers) west of the coastal city of Bergen.
The company said Statfjord is one of the oldest producing fields on the Norwegian continental shelf and the largest oil discovery in the North Sea.