FACTBOX: Gustav's impact on U.S. oil sector

(Reuters) - Tropical Storm Gustav was forecast to strengthen into a major hurricane in the Gulf of Mexico over the next few days, posing the biggest threat to U.S. energy infrastructure since the devastating hurricanes of 2005.

Energy companies with interests in the region were already evacuating staff and making preparations to halt operations Thursday as the storm lumbers out of the Caribbean on a track that could take it to the Gulf Coast early next week.

The government and the International Energy Agency said Thursday they are prepared to release emergency crude oil stockpiles if the storm causes a significant supply disruption.

Weather forecaster Planalytics said Wednesday the storm could force shut 85 percent of the Gulf's oil facilities.

Below is a list outlining the impact of Gustav on the U.S. oil sector so far:

EVACUATIONS

- Shell, which evacuated 300 workers on Wednesday, planned to evacuate an additional 400 workers on Thursday as it pulls all 1,300 people off its platforms in the Gulf of Mexico. The company planned to fly 600 workers from the Gulf on Friday and Saturday.

- Murphy Oil Corp said Thursday it is evacuating nonessential personnel from its Gulf of Mexico facilities ahead of Tropical Storm Gustav.

- Apache Corp said it was evacuating nonessential workers from platforms in the eastern Gulf of Mexico on Thursday due to the threat of Tropical Storm Gustav.