Supermajors BP and Chevron are taking steps to secure their US Gulf of Mexico assets ahead of Tropical Storm Zeta, the 27th named storm of the 2020 Atlantic season.

Both companies said Sunday they had begun evacuating staff from their operated assets in the region, and Chevron was also following storm preparedness procedures at its onshore facilities. Reuters reported that other operators including BHP and Equinor.

Anglo-Dutch supermajor Shell, meanwhile, said it would limit the movement of nonessential personnel to offshore assets and had "safely paused" some of drilling operations. A Shell spokesperson said there was no impact to production as of Monday morning.

US independent Murphy Oil told Upstream on Monday it was monitoring the storm but had not shut in production or evacuated any of its facilities in the US Gulf.

A spokesperson for Hess said the company is monitoring the storm closely and "implementing precautionary measures" for its facilities in the Gulf of Mexico as needed.

The US Bureau of Safety and Environmental enforcement later on Monday said ten platforms out of more than 640 in the region had been evacuated, and six out of 16 operated dynamically positioned rigs had been moved out of the storm's path.

The BSEE report, which relied on information from offshore operators, also said that 293,656 barrels per day of oil, equivalent to 15.87% of US Gulf production, had been shut in. Meanwhile, about 162.57 million cubic feet per day of natural gas, or 6% of the region's output, was also taken offline

On Monday morning, Zeta was about 140 miles south-east of Cozumel, Mexico and was expected to move over the Yucatan Peninsula overnight, according to the US National Hurricane Center. On its forecast track, the centre of Zeta will move over the southern Gulf of Mexico on Tuesday and approach the northern Gulf Coast on Wednesday.

Maximum sustained winds were near 70 miles per hour (110 kilometres per hour) with higher gusts. The storm is expected to strengthen into a hurricane later on Monday.

It has been a challenging year for Gulf of Mexico oil producers, with some companies having to withdraw workers and halt production at least six times as storms churned through the Gulf's offshore production region.

US Gulf of Mexico offshore oil production accounts for about 17% of total US crude oil production and 5% of total US dry natural gas production.

If Zeta strikes the US mainland, it would top the record of 10 named storms to make US landfall in one hurricane season that was set only weeks ago by Hurricane Delta.