CHARLESTON, W.Va. -- At least seven people were injured, four of them very seriously, after an explosion at a hydraulic fracturing operation at a gas well drilling pad in Doddridge County early Sunday morning, according to emergency officials.
Pat Heaster, the Doddridge County director of emergency services, said that four workers had potentially life-threatening burns. Those four were transferred to United Hospital Center in Bridgeport and then flown to West Penn Burn Center in Pittsburgh.
Heaster said that at least three, and possibly four, others were taken to area hospitals in private vehicles.
Kevin Kilstrom, an executive with Antero Resources, which owns the well, said that a total of five workers were eventually flown to the burn center in Pittsburgh.
A Doddridge County 911 dispatcher had earlier said that a total of eight people were injured in the explosion.
The names and conditions of the injured workers have not been released.
Randy Trent, the chief of the Bancs Volunteer Fire Department, said that as they rushed to the scene Sunday morning they met victims being rushed to the hospital in private vehicles.
"We were probably five to six miles from the well site," Trent said. "On W.Va. Route 18, they were transporting people by personal vehicle to meet us."
The five workers flown to West Penn Burn Center did not work for Antero, but worked for three different contractors, Kilstrom said. Kilstrom would not release the names of the contractors. Heaster said that he saw Nabors Industries trucks on the scene, indicating that they were one of the contractors.
The explosion happened just before 4 a.m. Sunday at the Hinterer 2H well on the Ruddy Alt pad on Brushy Fork in New Milton, Kilstrom said. Kilstrom said there are three wells on the pad.
The explosion did not happen at the drilling rig itself, which wasn't damaged, but at a nearby operation, Heaster said.
"They were fracking a well and something exploded, either in the pump or around the pump," Heaster said.
Heaster said that they were pumping water down a well, part of the hydraulic fracturing process for recovering gas trapped in shale rock. He said that the tanks that recover the water and other materials after they return to the surface are what exploded.
"The holding tanks that they were pumping into, that's what exploded," Heaster said. "It was a supplementary operation to the drilling process, the wellhead was not involved."
Trent said that the fire was about 50 yards from the wellhead.
"Once we were on the scene the flames were never more than six to eight feet high," Trent said.
Kilstrom said they did not yet know the cause of the explosion.
"We just started the investigation this morning," he said. "Within the next couple days we should get to the facts, but you never know."
The explosion caused a residual fire. The Bancs Volunteer Fire Department, the Smithsburg Volunteer Fire Department and the West Union Volunteer Fire Department were all on the scene from about 4 a.m. until about 7 a.m. Sunday.
Kathy Cosco, a spokeswoman for the West Virginia Department of Environmental Protection, said that two inspectors with DEP's Office of Oil and Gas were at the site. A representative of the federal Occupational Safety and Health Administration was also on the site Sunday evening.
"It appears that what exploded was a tank at the site," Cosco said in an email.
Messages left with Antero Resources corporate headquarters and their West Virginia offices were not returned Sunday.
Antero Resources owns at least 399 wells in Doddridge, Harrison, Ritchie, Tyler and Upshur Counties, according to a 2012 DEP database. The database lists 141 of those wells as being actively drilled, although, because the database is incomplete, that number is likely higher.
Antero has had safety problems in the past. Last August a spark at an Antero-owned well in Harrison County ignited methane gas several hundred feet underground, causing a fireball and a fire that burned for about an hour. Three workers were injured in that fire.
DEP cited Antero for failure to maintain well control for that incident.
DEP has cited Antero for 17 violations of state code in the past three years. Those have been primarily environmental violations -- for things like failing to prevent waste runoff, failure to report discharges and contaminating waterways.
One violation, from January 4, 2013, warned, "Imminent danger water supplys [sic] threatened by allowing pollutants to escape and flow into the waters of the state."
In June of last year Antero was drilling using water in Harrison County when they accidentally repressurized some old water wells, causing several geysers, one about 10 feet high, that flooded one nearby home and several garages.
In March 2011, state regulators shut down an Antero gas well in Harrison County after mud contaminated with drilling chemicals spilled into a nearby stream.
Reach David Gutman at firstname.lastname@example.org