Feb. 24 (Bloomberg) -- Most U.S. Gulf Coast oil premiums to West Texas Intermediate weakened as the difference between WTI and Brent oil decreased.

Brent’s premium to WTI shrank 9 cents to $15.70 a barrel based on April settlement prices, according to data compiled by Bloomberg. The premium was $8.55 at the end of 2011.

Thunder Horse’s premium to WTI narrowed 10 cents to $18 a barrel as of 3:43 p.m. New York time. Mars Blend’s premium decreased 75 cents to $12.90.

Poseidon’s premium narrowed 40 cents to $12.25 a barrel. Southern Green Canyon’s dropped 25 cents to $13.25 over WTI.

Light Louisiana Sweet’s premium widened 35 cents to $20.65 a barrel and Heavy Louisiana Sweet increased 50 cents to a premium of $21.50.

West Texas Sour’s discount narrowed 50 cents to $5 a barrel.

Syncrude oil’s discount was unchanged at $13.25 a barrel.

Western Canada Select was unchanged at $28.50 a barrel. Bakken oil’s discount was unchanged at $13.

--Editors: Richard Stubbe, Charlotte Porter

To contact the reporter on this story: Gene Laverty in Calgary at glaverty@bloomberg.net

To contact the editor responsible for this story: Bill Banker at bbanker@bloomberg.net