Sept 16 (Reuters) - U.S. cash grades were little changed on Tuesday as the spread between West Texas Intermediate and Brent narrowed slightly.
WTI Midland rose 5 cents, and WTI at East Houston, also known as MEH, gained 10 cents. Mars was unchanged.
The spread between Brent and U.S. WTI crude narrowed to settle at minus $4.30. A spread wider than minus $4 encourages U.S. exports.
Plains All American's crude oil pipelines linking the Permian shale basin to the Corpus Christi export hub in Texas are facing quality issues related to high mercaptans, or naturally-occurring sulfur compounds, according to sources familiar with the matter and a notice seen by Reuters.
Starting October 1, Plains will charge a half-dollar fee on every barrel that fails to meet mercaptan specifications on some of its pipelines in the Gulf Coast region, according to the notice.
Light Louisiana Sweet for October delivery gained 20 cents to a midpoint of a $1.90 premium and was seen bid and offered between a $1.60 and $2.20 a barrel premium to U.S. crude futures CLc1
Mars Sour firmed 30 cents to a midpoint of a 40-cent premium and was seen bid and offered between a 20-cent and 60-cent a barrel premium to U.S. crude futures CLc1
WTI Midland gained 5 cents at a midpoint of a $1 premium and was seen bid and offered between a 75-cent and $1.25 a barrel premium to U.S. crude futures CLc1
West Texas Sour eased 30 cents to a midpoint of a 10-cent discount and was seen bid and offered between a discount of 30 cents and 10-cent a barrel premium to U.S. crude futures CLc1
WTI at East Houston, also known as MEH, traded between a $1.15 and $1.55 a barrel premium to U.S. crude futures CLc1
ICE Brent November futures LCOc1 rose $1.03 to settle at $68.47 a barrel on Tuesday
WTI October crude CLc1 futures rose $1.22 to settle at $64.52 a barrel on Tuesday
The Brent/WTI spread narrowed 12 cents to last trade at minus $4.30, after hitting a high of minus $4.25 and a low of minus $4.44