For a brief, brave moment this year there was a sense the worst was over for the oil sector. This week, that feeling evaporated. Iran’s agreement to curtail its nuclear programme, potentially restoring its place as a leading crude exporter, was just the latest hunk of bearish news thrown at the oil market. Saudi Arabia and Iraq are pumping record volumes. US drillers have again added rigs to probe for oil in shale rocks. China’s furious fuel demand growth is easing. For investors pondering exposure to oil through futures, shares or bonds, standing back seems the safest course. The $50 a barrel plunge in spot oil prices from a year ago has been breathtaking. But to grasp the industry’s deepening woes, look at what futures markets are saying. The price of West Texas Intermediate crude delivered in December 2016 has fallen below $60 a barrel, the lowest since any exchange listed that futures contract. Between the financial crisis and last year, the contract levitated between $80 and $100.