The heaviest polar ice in more than a decade could postpone the start of offshore oil drilling in the Arctic Ocean until the beginning of August,” says this article on phys.org.
 
“A high pressure zone over the coast of Alaska, low winter temperatures and certain ocean currents have combined to bring unusually large amounts of ice not only to Alaska’s northern coast, but farther south in the Bering Sea as well, National Weather Service officials said.
 
“We’re seeing multiyear ice that they’ve not seen in such large quantities in over a decade,” said Shell’s vice president for Alaska operations, Pete Slaiby. Of particular concern, he said, is the region of the Chukchi Sea around the company’s Berger Prospect, which in normal years would be accessible by mid-July. This year, it may be unreachable until late July or early August.
 
Although offshore drilling operators in the 1980s and 1990s might have used icebreakers to plow a path to ice-bound drilling sites, Shell has committed to avoid icebreakers as a means of minimizing disturbances to wildlife, including polar bears, walrus and bowhead whales.”
 
 http://phys.org/news/2012-05-heavy-ice-shell-alaska-arctic.html