The world has changed for oil producers. When crude-oil prices were more than $100 a barrel just two years ago, the ensuing profits were huge, filling government coffers and swelling company earnings. Now prices barely cover the average cost to get the oil out of the ground in places like the U.K. Additional expenses, like taxes on profits, mean that the actual breakeven price for many projects is higher, and newer and more complex projects generally fall well above the average cash cost of production.