Oil and gas operators in Gulf of Mexico brace for storm

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Some Gulf of Mexico oil and gas operators began evacuating workers from offshore facilities Thursday but kept production flowing as a low-pressure system threatened to strengthen into a cyclone.

The National Hurricane Center said Thursday afternoon that a weather disturbance in the northwestern Caribbean Sea had become less organized overnight and had a 50 percent chance of becoming a tropical cyclone in the next 48 hours, down from a 70 percent chance.

Marathon Oil said Thursday it was evacuating workers not essential to production from its Ewing Bank platform, which can produce up to 9,700 barrels per day of oil and 8.2 million cubic feet per day of natural gas. Such workers would include cooks and maids.

"Marathon Oil's operated production has not been impacted at this time," spokeswoman Lee Warren said.

BP said it was evacuating nonessential workers from oil and gas platforms. It has four platforms in the central Gulf, including Thunder Horse, the biggest in the world.

The company said it had temporarily halted contracted drilling rigs, but platforms were still working.

"Oil and natural gas production at all BP-operated platforms remains online at this time," the company said.

Destin Pipeline also said pipelines in the Gulf of Mexico operated by BP were evacuating nonessential workers. The company said it would continue to accept natural gas flows as weather conditions permit.

Other companies said they were monitoring the storm.

—By Reuters with CNBC.com.