Texas refineries continued to run normally as rains, flooding and power outages began affecting Texas and Louisiana on Tuesday.
Tropical Storm Nicholas moved slowly toward the Houston metropolitan area after weakening from a hurricane.
Nicholas was about 15 miles (24 km) southwest of Houston, Texas by 7 a.m. Central Time (1200 GMT), heading northeast with maximum sustained winds of 60 mph (95 kph), the National Hurricane Center said in a bulletin, after it hit the Texas coast hours earlier.
Although Hurricane Ida knocked off significant amount of refining capacity in the Gulf Coast earlier this month, Texas refineries remained operating as of early Tuesday.
Motiva Enterprises' 607,000 barrel-per-day (bpd) Port Arthur, Texas refinery - the largest in the United States - was operating normally as Nicholas was passing over the area on Tuesday morning, said sources familiar with plant operations.
Royal Dutch Shell Plc's 302,800 bpd joint-venture Deer Park, Texas refinery was also operating normally on Tuesday morning after the passage of Nicholas, said sources familiar with plant operations.
Nicholas caused widespread power outages as it crossed over the Houston metropolitan area late Monday night and early Tuesday morning.
About 485,000 customers were without power in Texas on Tuesday, Reuters reported.
Texas energy company CenterPoint Energy Inc said on Tuesday that about 400,000 homes and businesses in its Houston-area service territory were without power.
More than 40% of the U.S. Gulf of Mexico's oil and gas output remained offline on Monday, two weeks after Hurricane Ida slammed into the Louisiana coast, according to offshore regulator Bureau of Safety and Environmental Enforcement (BSEE).
Damages to an offshore hub that pumps oil and gas from three major oilfields for processing onshore and power outages at onshore processing plants are responsible for the production losses.
All four liquefied natural gas (LNG) export plants operating along the Gulf of Mexico, meanwhile, remained in service early Tuesday, according to pipeline feedgas data from Refinitiv.
(Reporting by Laura Sanicola; Editing by Steve Orlofsky) ((Laura.Sanicola@thomsonreuters.com;))