--U.S. benchmark flat while Brent up slightly --Focus is on continued Houston shipping shutdown, Ukraine tensions --Market awaits weekly inventory data late Tuesday and early Wednesday By Christian Berthelsen NEW YORK--Oil prices treaded water Tuesday on a combination of bullish factors, from continued geopolitical tensions over the Ukraine to an extended shutdown of the Houston Shipping Channel, which has blocked crude deliveries. Light, sweet crude for May delivery on the New York Mercantile Exchange traded at $99.60 a barrel, unchanged from Monday's settlement. Brent crude, the global benchmark, was up 19 cents, or 0.1%, to $107.18 a barrel on the ICE Futures Europe exchange. A number of factors were at work on prices, including the decision to exclude Russia from what was the Group of 8 global leaders and impose economic sanctions over its decision to annex the Crimea region, ongoing supply troubles from Libya and the closure of the shipping channel in Texas since Saturday. A tanker accident there has created a backlog of 140 ships waiting to deliver crude imports and refiners have scaled back operations for the moment. These three factors are mildly bullish for prices, as they could temporarily crimp global and domestic oil supplies. The market is also waiting for inventory data late Tuesday and Wednesday that is expected to reflect another increase in overall U.S. crude supplies. The increase would be linked to reduced demand from U.S. refineries as they undergo seasonal maintenance. "Crude is seeing an amalgam of influences today, ultimately sending prices higher thus far," Schneider Electric analyst Matt Smith said in a note. Reformulated gasoline blendstock, or RBOB, for May delivery was down 0.24 cent to $2.8833 a gallon. May diesel was up 1.85 cents, or 0.6%, to $2.9286 a gallon. Write to Christian Berthelsen at christian.berthelsen@wsj.com

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