Brent crude prices reversed earlier losses to hit their biggest premium against U. S. futures in over three years on Thursday.
Brent crude futures rose to $77.78 a barrel, while U.S. West Texas Intermediate crude was $67.53 a barrel.
This pushed the premium of Brent to WTI beyond $10 a barrel, the largest since March 2015.
That spread has doubled in less than a month, as a lack of pipeline capacity in the U. S. has trapped a lot of output inland.
Prices for physical barrels of U.S. light sweet crude delivered at Midland are at their largest discount to the benchmark U.S. futures price in almost four years.
OPEC and non-OPEC producers have committed to cut output by 1.8 million bpd until the end of 2018 but will decide at a meeting in late June whether to prolong this.