(Recasts with Shell removing non-essential workers, details,background)
By Erwin Seba
HOUSTON, June 14 (Reuters) - Leading Gulf of Mexico oilproducer Shell Oil Co, the U.S. arm of Royal Dutch Shell Plc, said it was removing non-essential workers fromoffshore platforms as a precautionary measure ahead of alow-pressure storm system given an 80 percent chance of becominga tropical cyclone in the next 48 hours.
Shell said there would be no impact to offshore productiondue to the removal of non-essential workers ahead of the stormsystem's approach to the U.S. Gulf Coast.
The U.S. National Hurricane Center has warned that tropicalstorm conditions could appear along the coasts of Texas andLouisiana as early as Tuesday.
Earlier in the day, Shell said it was only monitoring thestorm system as did BP Plc.
But by Sunday night, Shell said it was withdrawing workerswho primarily provide support services to workers who operateoff-shore platforms.
"Shell has initiated efforts to reduce non-essentialpersonnel on some offshore assets as a precautionary measure inaddition to normal preparations for heavy weather," said Shellspokesman Ray Fisher.
Removal of non-essentials can also be the first taken priorto temporarily closing production, which happens when productionworkers are removed to safer areas on-shore.
U.S. oil companies have been closely watching the largetropical disturbance.
The system does not yet have a closed circulation needed toclassify it as a tropical storm or hurricane, but was producingwinds near gale force or about 38 miles per hour (61 kilometersper hour), or about half the strength of winds generated in theweakest hurricane.
The Hurricane Center as well as academic and private weatherforecasters are expecting a below-average number of stormsduring this year's Atlantic Ocean hurricane season. The seasonbegan on June 1 and lasts through Nov. 30.
Some forecasters have warned that the best chance for atropical storm to develop in the oil production areas off theU.S. Coast could come early in the season. A strong El Nino isexpected to form in the eastern Pacific later this summer andwould probably send high winds across the southern UnitedStates, disrupting tropical storm development.
The Gulf of Mexico produces 17 percent of U.S. crude oilproduction and 5 percent of dry national gas output, accordingto the U.S. Energy Information Administration.
Gulf Coast states of Texas, Louisiana and Mississippi arealso home to more than 45 percent of the nation's crude oilrefining capacity, according to the EIA. (Reporting by Erwin Seba; Editing by Bernard Orr and SandraMaler)