US Cash Crude-Grades mixed in volatile first day of roll trade

March 22 (Reuters) - Grades were mixed on Wednesday on the first day of the cash roll period, dealers said, as traders squared their positions. WTI Midland and Mars were unchanged, while Midland at East Houston, known as MEH, gained 15 cents and Light Louisiana Sweet was up 40 cents. Grades typically tend to be more volatile during the roll period as traders use the window to net out exposures. WTI widened 20 cents to a minus $5.85 discount to Brent. Exports tend to rise when WTI trades more than $6 below Brent, as it makes U.S.-linked grades more affordable for foreign buyers. Sour grade Mars had touched a 11-month high this week on strong export and refining demand, while WTI Midland and MEH weakened to their lowest levels in more than two months as release of sweet oil from the Strategic Petroleum Reserve has hurt market demand. Meanwhile, crude stockpiles rose 1.1 million barrels last week to a 22-month high, according to data from the U.S. Energy Information Administration. Analysts in a Reuters poll had forecast a withdrawal of 1.6 million barrels.

Still, the official EIA data showed a smaller build than the increase of 3.3 million barrels reported on Tuesday by the American Petroleum Institute, an industry group. In refining news, the hydrocracker was shut at Exxon Mobil Corp's 619,024-barrel-per-day (bpd) Beaumont, Texas refinery, according to sources.

* Light Louisiana Sweet for April delivery fell 10 cents to a midpoint of a $3.20 premium and was bid and offered between a $3.00 and a $3.40 a barrel premium to U.S. crude futures .
* Mars Sour remained unchanged to trade flat at its midpoint and was bid and offered between a 20-cent premium and a 20-cent discount a barrel to U.S. crude futures .

* WTI Midland remained unchanged to trade at a midpoint of a $1.10 premium and traded between a 90-cent and a $1.30 a barrel premium to U.S. crude futures .
* West Texas Sour gained 50 cents to a midpoint of a 10-cent premium and was traded between flat and 20 cents a barrel premium to U.S. crude futures .

* WTI at East Houston, also known as MEH, traded between $1.25 and $1.75 over WTI.
* ICE Brent May futures rose $1.37 cents to settle at $76.69 a barrel.
* WTI April crude futures rose $1.23 to settle at $70.90 a barrel.
* The Brent/WTI spread narrowed 20 cents to minus $5.85, after hitting a high of minus $5.58 and a low of minus $5.86. (Reporting by Arathy Somasekhar in Houston; Editing by Paul Simao)

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