A fire that has burned since early Tuesday at a Chevron Appalachia LLC natural gas well in southwest Pennsylvania had nearly burned out on its own by Thursday afternoon, said a state official, adding that a team of specialists was preparing to cap it and another well on the same pad.

The Lanco 7H, in Dunkard Township, about 70 miles south of Pittsburgh and near the West Virginia border, erupted into flames after an explosion ignited it at about 6:45 a.m. EST on Tuesday (see Shale Daily, Feb. 11). Overnight, John Poister, a spokesman for the Pennsylvania Department of Environmental Protection (DEP), said moisture from inside that well was carried out with the ejection of natural gas, helping to extinguish the flames.

The Lanco 7H shared a pad with two other wells, though, and after the fire died down, specialists and local emergency response officials realized a second well, the Lanco 6H, was on fire too. That well continued to periodically spew flames as the gas came into contact with blazing hot metals, Poister said.

A team of specialists from Houston-based Wild Well Control was dispatched to the site late Tuesday and as the fire calmed Thursday, they were making preparations at a nearby staging area to cap both wells.

"We are assessing our options so that we can proceed with the most appropriate and safest approach to the fire," said Kent Robertson, Chevron upstream spokesman. "We are developing a site-specific safety plan to identify and establish mitigation plans for all potential hazards associated with extinguishing the fire and controlling the well."

Robertson said specialized firefighting equipment had arrived on site and the specialists were crafting plans to shut off the flow of gas.

"Out of an abundance of caution, we have begun to monitor air, surface waters and noise in the area for any signs of impact," he said. "At this point, we have no indications that this incident has created any further safety risks."

The accident left one person hospitalized and another worker from the oilfield services company Cameron International who remains unaccounted for and is now presumed dead.

Poister said Wild Well would soon begin removing hot metal and other debris from the well pad ahead of its plans to cap the wells. As a result, gas monitors were placed at all four corners of the site as a safety precaution.

Meanwhile, DEP Secretary Christopher Abruzzo arrived on scene to tour the well site and fire on Wednesday. He returned early Thursday and had joined Chevron, Wild Well and local officials in a command center that has been set up to deal with the response.

A cause remains unclear (see Shale Daily, Feb. 12) and it could take days or weeks to determine what caused the explosion. Robertson said Chevron would be in a better position to provide more details as it continues to gather additional information.