Oil prices climbed for a third day on Wednesday, hovering above $117 a barrel as Tropical Storm Gustav spun toward the Gulf of Mexico on a possible collision course with offshore energy installations. Also on Wednesday, the Energy Department reported a surprise drop in U.S. crude supplies. However, the report did not seem to be affecting trading as oil investors focused their attention on Gustav. Royal Dutch Shell PLC and BP PLC said they have begun evacuating some workers from offshore rigs scattered throughout the Gulf, home to about a quarter of U.S. crude production and much of its natural gas. Though it was too soon to know where the storm would hit, some models showed Gustav taking a path toward Louisiana and other Gulf states devastated by Hurricanes Katrina and Rita three years ago in a double blow that sent energy prices soaring. One business weather research firm predicted as much as 80 percent of the Gulf's oil and gas production could be shut down as a precaution if Gustav enters the region as a major storm. "A bad storm churning in the Gulf could be a nightmare scenario. We might see oil prices spike $5 to $8 if it really rips into platforms," said Phil Flynn, analyst at Alaron Trading Corp. in Chicago. Light, sweet crude for October delivery rose as high as $119.63 on the New York Mercantile Exchange before easing back in afternoon trading to $117.67, still up $1.40. The contract added $1.16 on Tuesday to settle at $116.27 a barrel. The storm also boosted natural gas prices, which gained 12.2 cents to $8.40 per 1,000 cubic feet. Gustav struck Haiti on Tuesday as a hurricane, pummeling the impoverished country with 90 mph (144 kph) winds and heavy rain before moving toward Cuba. At least 11 people were killed in Haiti and the Dominican Republic. Gustav was later downgraded to a tropical storm but was expected to regain strength, possibly becoming a dangerous Category 3 storm by next week, forecasters said. Jim Ritterbusch, president of energy consultancy Ritterbusch and Associates in Galena, Illinois, said a big threat was to oil refineries dotting the Gulf Coast from Texas to Louisiana. A shutdown in refining there would likely lead to a sudden jump in retail gas prices around Labor Day weekend, a time when many Americans take to the road for end-of-summer vacations. "There's a strong chance that by Friday we could see some fairly significant pump price increases," Ritterbusch said. "Crude can be replaced and brought in via tanker, but bringing a damaged refinery back up again can take a long time, as we saw with Katrina and Rita."