Refineries around the world are using more crude oil. To get the cheapest supplies around, they don’t have to look any further than their own storage tanks. When a global glut of crude oil sent prices plunging to near-six-year lows in the first quarter of the year, refineries started stocking up. The market gave them an incentive to do so: Oil prices for later in 2015 were higher than immediate prices, making refiners and traders eager to buy crude for cheap and store it to use or sell in the future. The strategy worked. As more and more oil entered storage , pushing U.S. inventories to the highest level in more than 80 years and prompting some companies to stash oil on ships in the ocean, the amount of crude immediately available to buyers fell. Add in a cold winter that spurred demand, and prices rallied. But with the […]