Obama banned certain new leases through 2022.

From a related report:

http://www.pressherald.com/2016/11/18/obama-administration-b...

Even if the economics of Arctic drilling improve and a Trump administration wants to reopen the area to exploration, both oil company officials and environmental groups say, Trump would be unable to toss out the five-year plan immediately. To undo the Obama administration’s ban, a new administration would have to prepare a supplemental report, which could take as long as two years, depending on whether it needs to prepare a new environmental impact statement.

After that, the federal government would have to organize a lease sale for companies interested in drilling there.