Lisa Sanders

As crude-oil futures climbed above $51 a barrel this week, analysts threw up their hands and wondered why.

ConocoPhillips’ decision to bow out of a lobbying group focused on opening up the Arctic National Wildlife Refuge to drilling means that two of the largest operators on Alaska’s North Slope are no longer actively advocating exploration in the refuge.

Estimating how much oil a company owns thousands of feet underground is, at best, a slippery business.