"Crudes premium for delivery in eight years compared with the June 4 price rose 86 percent since the BP Plc-leased Deepwater Horizon rig in the Gulf of Mexico exploded April 20, based on the June 4 price.
Oil for delivery in December 2018 was more than $21 a barrel more expensive than for delivery next month, compared with $11 before the disaster."
That would affect the NPV calcs in out favour.