By Kristen Hays and Erwin Seba
HOUSTON (Reuters) - Tropical Storm Nate formed over the Bay of Campeche in the Gulf of Mexico Wednesday afternoon as oil and gas producers in the prolific basin restarted operations in the wake of Tropical Storm Lee.
Companies said they were monitoring Nate, the 14th named storm of the Atlantic hurricane season, which the National Hurricane Center said could become a hurricane by Friday.
Widely divergent forecasting models showed the slow-moving storm could move west into Mexico or north-northwest toward the U.S. Gulf Coast in the coming days.
Late Wednesday, Nate had not affected Mexico's oil production, but two major crude exporting ports were shut down for safety reasons.
U.S. crude oil prices rose more than $3 a barrel on Wednesday, bolstered in part by slow recovery from Lee and threat of further disruptions to energy infrastructure.
On Wednesday, 516,451 barrels per day of Gulf oil output, or 36.9 percent, and 958.4 million cubic feet per day of natural gas production, or 18.1 percent, remained shut, the U.S. Bureau of Ocean Energy Management said.
Those figures represented substantial decreases from Tuesday, when BOEM said 60.5 percent of oil and 41.6 percent of natural gas output was shut in the basin.
Lee came ashore and weakened on Sunday, but high winds and rough seas lingered, hampering restart efforts in areas south of Louisiana and Mississippi. The weather improved early Tuesday and companies began to bring workers back to platforms and restart production.
Before markets closed on Wednesday, Gulf Coast refined products traders said they saw no weather effects on differentials. Gulf cash crude markets were flat to stronger. "Crude is tight, period, so everyone is watching closely," a trader said of the weather in the Gulf.
A marine control operator at the state oil monopoly Pemex said the company's major oil platforms in the Bay of Campeche were operating normally and no workers had been given instructions to evacuate.
The bad weather closed the Dos Bocas and Cayo Arcas exporting ports on Mexico's Gulf, which together handle the bulk of the world's No. 7 oil producer's crude exports.
The Coatzacoalcos port remained open, the transport ministry said in a statement.
Kelly op de Weegh, a spokeswoman for major Gulf oil and gas producer Royal Dutch Shell, said the company was redeploying workers to platforms and ramping up production.
But Shell and other companies were also monitoring the new storm.
The Gulf's two areas with the heaviest concentrations of oil and gas infrastructure -- Mississippi Canyon and Green Canyon -- are south of Louisiana.
Tropical cyclones become named tropical storms when their winds exceed 39 miles per hour and become hurricanes when their winds reach more than 74 mph.
(Additional reporting by Bruce Nichols in Houston and Mica Rosenberg in Mexico City; Editing by John Picinich and David Gregorio)
