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By Anjana Anil

July 22 (Reuters) - The U.S. National Hurricane Center said on Wednesday that Tropical Storm Bertha has made landfall in St. Bernard Parish, Louisiana.

The storm is located about 45 miles (70 km) southwest of Biloxi, Mississippi and about 40 miles east of New Orleans, with maximum sustained winds having decreased to 45 miles per hour, the Miami-based forecaster said.

The center of Bertha will move near or along the Louisiana and upper Texas coasts through Thursday and then track farther inland into Texas on Friday, the NHC said in a Wednesday afternoon advisory. Additional weakening is expected over the next two days, it said.

The region is home to major deepwater oil and natural gas producers including Shell SHEL.L, BP BP.L, Chevron CVX.N and Occidental Petroleum OXY.N, while a refining corridor accounting for about half of the country's capacity of 18.4 million barrels a day stretches from Corpus Christi, Texas, to Pascagoula, Mississippi.

About 1.5 million barrels of oil production could be lost across the U.S. Gulf through the duration of the storm, a marked increase from the 10,000 barrels impacted by Tropical ‌Storm Arthur last month, according to a model forecast from consulting firm Earth Science Associates.

The companies with the highest potential exposure to the storm are BP, Chevron, Murphy Oil MUR.N, Shell and Talos Energy TALO.N, according to the Earth Science data.

Chevron earlier this week said it had shut in production at its Petronius facility and evacuated personnel from the platform as a precaution. BP removed some non-essential personnel from its Thunder Horse and Na Kika platforms, while Murphy Oil, Shell and Talos did not immediately respond to requests for comment.

The U.S. Gulf of Mexico's federal offshore waters produced nearly 2 million barrels per day of crude oil in March, which is about 14% of total U.S. output.