Most North American oil grades weakened in the U.S. Gulf Coast, the Midcontinent and Canada after inventories rose the most in more than five months.
U.S. oil stockpiles gained 8.53 million barrels last week, the most since March 30, to 367.6 million, the Energy Department reported, as producers restored output in the Gulf of Mexico after Hurricane Isaac and imports rose. Analysts polled by Bloomberg expected an increase of 1 million.
Heavy Louisiana Sweet’s premium to West Texas Intermediate lost 85 cents a barrel to $17.50 at 2:02 p.m. in New York, according to data compiled by Bloomberg. Light Louisiana Sweet’s added 45 cents to $19.75 a barrel.
Poseidon’s premium narrowed $2.45 to $8.55. Mars Blend decreased $2.20 to $9.55 a barrel over WTI and Southern Green Canyon lost $1 to a premium of $8.50.
The premium for Thunder Horse, a sour crude with lower sulfur content than Mars, Poseidon and Southern Green Canyon, widened $1.80 to $18 above WTI.
Bakken’s premium lost 50 cents to $5 a barrel. Syncrude’s premium to WTI narrowed 50 cents to $13.75 a barrel.
Western Canada Select’s discount widened 50 cents to $7.75 a barrel below the U.S. benchmark.