Energy futures sold off Tuesday at the New York Mercantile Exchange as traders reassessed their forecasts for the supply and demand of crude oil, gasoline and other products.

Crude fell 51 cents to settle at $63.10 a barrel, and reformulated gasoline slid 5 cents to $2.06 a gallon. Heating oil closed 6 cents weaker at $1.80 a gallon.

The near-term natural gas contract declined 11 cents to $7.42 per million British thermal units.

Although oil for May delivery opened strongly on a bullish mix of supply problems and geopolitical issues, the fact that a glut remains near the hub for West Texas Intermediate crude in Cushing, Okla., pushed prices lower in the afternoon.

Meanwhile, concerns about

Enbridge's

(ENB) - Get Report

breached pipeline that runs from Alberta, Canada, to refineries near Chicago failed to support crude prices. The pipeline, which transports 450,000 barrels of oil a day, was shut-in on Sunday night.

Enbridge said it doesn't know when it will reopen the pipeline. "There are lots of branches of that pipeline, so losing one doesn't stop everything from moving," Bentz said.

The fact that energy prices fell for the session doesn't matter much, according to Bentz. What's important is whether they can remain down.

"In order for crude prices to stay at their current levels, the markets must dodge concerns about summer gasoline supplies, the possibility of more refinery fires or pipeline leaks, and the hurricane season. Those are a lot of hazards to dodge," he said.

Elsewhere, tensions have soared in Nigeria just days ahead of the presidential vote there. Violence has been reported throughout the country, and the main independent watchdog group claims that it was denied access to voting locations in last weekend's gubernatorial elections, in which the incumbent party won by large margins.

Allegations of ballot-stuffing and other tampering have been widespread. Nigeria, a member of OPEC, is one of the world's top oil-producing nations, and unrest there can rattle the crude market.

Royal Dutch Shell

(RDS.A)

is hoping for peaceful elections and a decrease in violence so that it can restart its operations in the Forcados oilfields in Nigeria's delta region. Shell's operations there have been shut down for more than a year due to the political turmoil.

Meanwhile, energy stocks followed commodity prices lower. The CBOE Oil Index dropped 0.4% to 682.41.

ConocoPhillips

(COP) - Get Report

finished fractionally lower at $70.43.

Chevron

(CVX) - Get Report

was up slightly at $77.96, and

Exxon Mobil

(XOM) - Get Report

moved a bit higher to $78.40.

Entergy

(ETR) - Get Report

announced that it expects to earn $1.01 a share in the first quarter of 2007, 10 cents lower than the analyst consensus but 9 cents higher than the same period one year ago. Entergy blamed the miss on a refueling problem at its Indian Point 3 nuclear plant, as well as general cost increases in its utility business.

Shares of Entergy closed 0.7% higher at $111.89.

Among analyst actions,

Callon Petroleum

(CPE) - Get Report

advanced 2.3% to $14.39 after being upgraded by AG Edwards to buy from hold.

China Petroleum

(SNP) - Get Report

was downgraded by Citigroup to sell from buy, depressing the stock 2.9% to $89.92.

CIBC World Markets downgraded

Solarfun Power

( SOLF) and

JA Solar

(JASO)

to sector perform from sector outperform. Solarfun plummeted 15.2% to $15. JA Solar dropped 11.6% to $24.93.

Aventine Renewable Energy

( AVR) was downgraded by Goldman Sachs to neutral from buy, and its stock slid 4.1% to $19.41.