Offshore oil production in the US Gulf of Mexico had been reduced by 22% as of Tuesday because of concerns over Tropical Depression Nine moving in from the Caribbean.
The Bureau of Safety and Environmental Enforcement (BSEE), an agency under the Department of the Interior, said several producers in the east of the US Gulf had shut in production on a total of nine platforms, half of them operated by Shell or BP.
Shutting in is when a low production cap is deliberately set, often in anticipation of a severe weather event.
Around 10% of natural gas production was also shut in.
Transocean went ahead with its previously announced plan to move two rigs.
There were also more cases of firms evacuating non-essential personnel from rigs and platforms, bringing that total to nine rigs, too.
Evacuations have been happening for several days since the storm, still without an official name, started moving from Cuba and towards the Florida Keys.
The US National Hurricane Centre in Miami, Florida said the storm had moved north-northwest from Cuba and was moving at 7mph with winds of 35mph. It was expected to make landfall north of Tampa, Florida.