McClatchy Newspapers reported Monday that the containment dome aboard a barge called the Arctic Challenger was damaged in a testing scenario off the coast of Washington, where the 38-year-old barge is being retrofitted by contractor Superior Energy Services.
"It is clear that some days will be required to repair and fully assess dome readiness," Shell said in a statement, adding that it would not "conduct any operation until we are satisfied that we are fully prepared to do it safely."
The Interior Department was also unwilling to certify Shell's drilling operation until the containment barge and dome were ready.
The dome is used, if necessary, to contain an underwater oil spill.
As a fall back position, Shell said it would drill "top holes," in preparation for the 2013 drilling season, but it had also run into problems with this preliminary step due to seasonal ice beginning to encroach on operations.
But Shell said it would get done what it could before ice closed operations down.
"The top portion of the wells drilled in the days and weeks ahead will be safely capped and temporarily abandoned this year, in accordance with regulatory requirements," the company said in a statement.