Energy Sector Roundup: Gas up

"Our source said that, thus far, the strike has prevented Allis-Chalmers from driving to certain locations and delivering equipment, but did not quantify how many or to what degree rigs may be affected," Curran said. "Allis-Chalmers does have some standby agreements in place, yet historically these havent resulted in significant, timely recoveries."

Last week the oil and gas services company reported first-quarter earnings above Wall Street's forecast. But Curran says the Argentina strike, which began April 30 and reduced output from 6,000 fields, could hurt the company's profit.

"It's one of the main reasons we're at 28 cents (per share) for Q2 2008E versus guidance of 29 cents to 32 cents and current consensus of 30 cents," he said.

More Trouble in Nigeria

Gunmen in southern Nigeria hijacked an oil-services vessel carrying 11 crew members, according to a military spokesman.

They want about $250,000 for the release of the boat and the crew, including one Portuguese and one Ukrainian, said military spokesman Maj. Sagir Musa.

The boat, used for maintaining oil infrastructure in Africa's biggest petroleum producing country, was taken in the southern Niger Delta.

Numerous armed militant and criminal groups roam the delta, a vast region of creeks, swamps and rivers but few roads. Militants frequently blow up oil infrastructure or attack security forces to press demands for more oil-industry revenue for their impoverished region.

More than 150 foreigners were kidnapped for ransom in the region in 2007. The hostages are normally released unharmed after payment is delivered, although several have been killed or injured during botched seizures or rescue attempts.

Nigeria supplies about a million barrels of oil a day to the U.S., according to the Energy Department.