Pennsylvania environmental officials on Monday suspended drilling operations of a Marcellus Shale natural-gas operator whose Clearfield County well erupted last week into an uncontrolled geyser of gas and wastewater.
Department of Environmental Protection Secretary John Hanger ordered Texas-based EOG Resources Inc. to suspend its drilling activities in Pennsylvania until DEP has completed an investigation into the spill Thursday at the Punxsutawney Hunting Club.
The 16-hour eruption caused no injuries and no fire, and DEP officials on Monday described the environmental damage as "modest" - no fluids reached any streams.
A contractor dug trenches to contain 35,000 gallons of spilled fluid, mostly salt water that was trapped deep underground, but including trace elements of drilling chemicals.
The accident's timing was critical, coming amid Gov. Rendell's effort to push a reluctant legislature to enact a tax on natural gas extracted from the Marcellus Shale, the mile-deep formation that underlies much of Pennsylvania and several surrounding states.
"We needed a severance tax even before the accident," Rendell said, adding he hopes the accident will mean the industry will "stop battling the tax."
The blowout also bore a stark similarity to the BP oil-well disaster in the Gulf of Mexico. In both accidents, a mechanical safety device known as a blowout preventer failed.
In a statement, EOG Resources said Monday that the blowout preventer had been successfully tested Thursday morning. But it said the seal integrity was compromised when the well pressure surged.
"EOG regrets this incident and will continue to cooperate and work with the PADEP and other Pennsylvania authorities," said Gary L. Smith, EOG's regional vice president and general manager. EOG, headquartered in Houston, was called Enron Oil & Gas until 1999.
Though industry officials describe such drilling accidents as rare, a Marcellus well in West Virginia exploded in flames early Monday, injuring seven rig workers, none critically. That accident, on a well operated by Chief Oil & Gas. L.L.C., did not involve a failed blowout preventer.
But the accidents underscore the mixed blessing of natural-gas development, an economic bounty that critics say comes with unknown environmental risks and unsettling political consequences.
Rendell pledged the state's investigation would be independent.
"We are very concerned about what happened here and we're not relying on the company to tell us what went wrong," he said.
Hanger said the investigation will look at EOG's response after the blowout occurred at 8 p.m. Thursday. The company called 911, and the Pennsylvania Emergency Management Agency was notified.
But rather than calling the state's 24-hour emergency response line, EOG left a voice mail at 10 p.m. with a DEP employee. DEP staff did not arrive on the site until 4 a.m.
While the gas shot 75 feet into the air and eight rig workers retreated to safety, EOG notified Wild Well Control Inc., a Houston contractor that specializes in containing blowouts. Specialists flew in from Texas and capped the well about noon on Friday.
The well that blew out is one of four wells located on the same drilling pad at the hunting club in Lawrence Township. The site is near Moshannon State Forest, and the nearest house is more than a mile away.
EOG has permits for 265 active wells in Pennsylvania, 117 in the Marcellus Shale formation.
While DEP said that none of the fluid that escaped flowed into streams, they were monitoring the spill to determine whether any chemicals used in hydraulic fracturing - the process known as "fracking" - seeped through the soil into underground water supplies.
Hanger said that a spring in the area showed an increase in conductivity, an indication of potential seepage of chlorides contained in salty well brine. EOG had collected the discharge for disposal.
Hanger called fines "a likely outcome" after completion of the review.
Investigators don't know the cause of the blowout.
According to DEP's records, the major drilling of the well occurred in the late winter, when a large rig capable of drilling horizontally completed its work on March 3. That was also the last date that DEP inspectors visited the site - they found no violations during three visits.
Contractors returned in May to hydraulically fracture the well over 12 days. The process involves the injection of water, sand, and chemicals under high pressure to shatter the gas-bearing rock so that the fuel can be recovered. The frack job ended on May 28.
EOG told DEP that its frack fluid contained three chemicals that constituted less than one-quarter of 1 percent of the total fluid pumped down the well. Some of that fluid was recovered after the fracturing job, but some remained in the well and likely came up during the blowout, officials said.
EOG began well-completion operations on June 1 to connect the well to a pipeline. The blowout occurred two days later.
High pressure in an oil or gas well is desirable - the pressure is what brings the fuel to the surface. Blowouts occur when the pressure surges and overwhelms control mechanisms.