Shell deployed divers and remote vehicles below the North Sea oil platform to stop flow of oil spilling from its Gannet platform last week. Shell noticed the leak Aug. 11.
The company reported about 1,500 barrels leaked from the platform. None of the oil reached shore.
Hugh Shaw, the British government's maritime authority in charge of the spill, said that while there was some sheen observed in the area, that can be expected as workers stir up sediment during the inspection and repair operations.
"The risk of further oil release has considerably reduced following a successful operation to return raised sections of the pipeline to the seabed with concrete mattresses," he said. "The latest survey shows a few sections are lying just above the sea floor but operations continue to add additional mats to reduce the risk further."
Shell said next step would be to remove oil built up in the flowline. The company said it established a team to investigate the cause of the leak and would work with government officials as they conduct their own probe into the spill.