HOUSTON—Tropical Storm Barry slowly moved on to the Louisiana coast and quickly weakened from hurricane strength on Saturday afternoon, leaving in its wake 70% of U.S. Gulf of Mexico oil production shut in, the U.S. government said.

One refinery was taken out of production on Friday due to the threat of flooding, while seven others in southeastern Louisiana remain in operation on Saturday, the companies and sources familiar with plant operations said.

The Louisiana Offshore Oil Port, the only U.S. location loading and offloading giant oil tankers, was operating normally on Saturday, a spokesman said.
Barry reached hurricane strength on Saturday morning before coming ashore near Intracoastal City, La., at about 1 p.m. CDT and quickly weakened with maximum sustained winds of 70 mph.

The one shut refinery, Phillips 66's 253,600-barrel per day (bbl/d) Alliance, La., plant, was not significantly affected by Barry as it came ashore, said company spokesman Joe Gannon.

"Utilities at the facility remain active to allow for restart activities to begin as soon as it is safe to do so," Gannon said.

Barry is forecast to move slowly across Louisiana as it did across the Gulf since emerging off the coast of Florida on Wednesday. The storm is expected to drop 2 ft of water in areas east of its center over the weekend.

Also in the U.S.-regulated areas of the Gulf of Mexico, natural gas output from offshore platforms had been cut by 56%, or 1.5 billion cubic feet per day, the U.S. Bureau of Safety and Environmental Enforcement (BSEE) said on Saturday.

Oil producers have shut 283 offshore platforms, or 42%, in the northern Gulf of Mexico, BSEE said.

Exxon Mobil Corp.’s 502,500-bpd Baton Rouge, Louisiana, refinery was continuing operations, spokesman Jeremy Eikenberry said.

Royal Dutch Shell PLC's 225,300-bpd Norco, Louisiana, refinery was running with essential staff only and no reduction in production, sources familiar with plant operations said.

Shell spokesman Ray Fisher confirmed the Norco refinery and the company's 221,270 bbl/d-Convent, La., refinery were operating, but did not discuss production levels.

The major threat to the refineries is heavy rainfall, with wind seen as a lesser risk as the plants are east of the storm’s center, which produces the highest winds.