Shale gas fire rages on

In its most recent update on its Marcellus shale gas-targeting Lanco 7H well in southwestern Pennsylvania, which exploded on Tuesday morning, Chevron revealed that one of the 19 workers at the time of the accident was still missing.

"One contractor employee remains unaccounted for," Chevron said.

"Our thoughts and prayers are with this family and with all of our employees, contractors and emergency responders."

Efforts to contain the ongoing gas-fuelled fire are still at the planning stage.

"Chevron and Wild Well Control are on location and assessing the situation," the well operator said.

"At this time we cannot speculate how long the fire may burn.

"As we gather more information at the wellsite, we will be in a better position to provide more details."

The major does not believe the fire is causing any further safety risks and is preparing a location to serve as a firefighting staging area.

"Our plans include efforts to control the well by shutting off the flow of natural gas and taking all appropriate procedures to protect the other wells on the pad," Chevron said.

"We are closely monitoring the status of the adjacent two wells and are developing contingency plans for those wells, if necessary."

Chevron also shed more light on what happened before the accident at the well pad site.

"The wells were in the final stages of preparation before being placed into production," it said.

"There was no drilling or hydraulic fracturing taking place at the time.

"At the time of the incident, preparations were being made to run tubing, which is often done prior to bringing wells into production."

Pennsylvania Department of Environmental Protection spokesman John Poister recently told Reuters that the well could be on fire for some yet.

"There's a large amount of gas in the well and it could burn, if we just sat there and watched it, for months or years," Poister reportedly said.

US LNG threat downplayed

Sempra Energy's recent US government approval to target Japan and other key export markets for its proposed Louisiana-based Cameron LNG project has not concerned too many analysts.

While shale-booming American gas prices are far cheaper than what Asian markets are used to, Deutsche Bank analyst John Hirjee indicated that volatility was still possible.

He told The Australian that recent storms in the US had pushed up gas prices there dramatically - and were up to $US8 ($A8.87) per million British thermal units at one stage.

"When you take that and then add the liquefaction and transport costs to get it into our region, then it starts to mean the competitive aspect of that has been diminished because of a higher domestic US gas price," the analyst reportedly said.

"If the US gas price starts to go up to the $5-plus region on a sustainable basis then the advantage of the US being cheaper starts to diminish."

HSBC Australia and New Zealand chief economist Paul Bloxham noted that Australia's LNG projects had locked in long-term contracts and the US still had a long way to go.

"Australia's gas story still has a strong medium term future and that is despite the fact the US may bring on some capacity to export gas to Asia," Bloxham reportedly said.

Nigerian auction

Royal Dutch Shell's plans to sell a 30% stake in four Nigerian oil blocks, in which majors Total SA and Eni also have 10% and 5% stakes, have reportedly attracted bids from commodity traders Glencore Xstrata and Mercuria.

Reuters further cited a confidential Shell document that revealed "new details" in its report.

"The consensus of five sources is that the combined 45% stake in blocks OML 18, 24, 25 and 29 is worth around $3 billion but could fetch even more due to inflated values put on assets in a country with an increasingly wealthy elite," the newswire reported.

"The blocks' combined output averaged 90,000 barrels of oil and 60 million standard cubic feet of gas per day in 2012 and they hold reserves of 4.6 billion barrels of oil equivalent, the Shell report seen by Reuters said.

"A 30-year lease on these blocks was renewed in 1993, the document said.

"Shell has held a stake in them for decades longer and it is unclear how much the firm originally paid."