Oil prices rise on Nigeria supply concerns

Nigeria is the fifth-largest oil exporter to the U.S., and a shutdown would force American refineries to replace 630,000 barrels per day of crude. Nigerian workers, who have been protesting the end of long-standing government fuel subsidies, may cut off oil production starting Sunday.A number of international oil companies operate in Nigeria, including Exxon Mobil, Chevron, Frances Total, Royal Dutch Shell, ConocoPhillips, Brazils Petrobras and others. Much of the production is on offshore platforms.Benchmark crude jumped by $1.38 to $102.25 per barrel in late morning trading in New York. Brent crude rose by $1.57 to $113.63 per barrel in London.In other energy trading, the price of natural gas continued to drop Thursday after the government said U.S. supplies are well above normal for this time of year.Natural gas prices fell 9 cents, or 3.1 percent, to $2.69 per 1,000 cubic feet in morning trading in New York. Theyve fallen by 13 percent in the past week as relatively mild winter weather cut heating demand. About half of U.S. homeowners use natural gas for heat.Americans are using less at a time when energy companies are pumping more from fields around the country. Production is booming as rising crude oil prices encourage the industry to tap new oil and gas fields in North America. Oil and gas are often found in the same geological formations.Gas supplies have ballooned since fall. On Thursday, the Energy Information Administration said supplies are 13.4 percent higher than what they were a year ago and 17 percent above the five-year average.Heating oil rose by 5 cents to $3.11 per gallon, while gasoline futures increased by 3 cents to $2.79 per gallon.