Ingram Publishing/Thinkstock
Photo credit: Ingram Publishing/Thinkstock

A blast at a natural gas well site near New Milton in Doddridge County, W.Va., on July 7 injured at least five people. The cause of the explosion is still not known but state and federal officials are investigating, the Huffington Post reported.

The site is operated by Antero Resources, which has also appointed independent investigators to examine the incident. Pat Heaster, director of emergency services in Doddridge County, stated that the explosion was triggered by a spark and a resulting fire, possibly occurring when drilling fluids were pumped into a storage tank.

Work on the Hinterer 1H well has been stopped until the investigation by the state Department of Environmental Protection (DEP), the Occupational Safety and Health Administration (OSHA) and the two independent safety firms hired by Antero Resources has been completed.

Antero vice president Alvyn Schopp said that all five injured people are being treated for varying degrees of burn injuries at a medical center near Pittsburgh but he did not provide details on their condition, including whether any of the injuries were life threatening. The victims' names were also not disclosed.

Schopp explained that the workers were nearly finished with their work on the well and were inserting a production tube into the metal casing surrounding the drilled hole when methane gas somehow caught fire. The source of the ignition is not yet known, he added.

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DEP spokeswoman Kathy Cosco stated that the explosion damaged two tanks holding flow back water that the company had been reusing, but the fluid did not spill because of the secondary containment system which managed to contain it. No contamination to any nearby streams has been detected and the nearest residential property, located about about a half-mile away, was unaffected, she said. Cosco also said that the company had been licensed to drill five wells altogether but not all of them have been drilled yet.

Investigators suspected that methane vapors inside one of the tanks had exploded but at present they are not entirely sure of what the ignition source was, she went on. DEP officials are looking at whether it all started at a pump that the crew had been working on, but Cosco stated that the mechanics of the explosion will be investigated by the OSHA. The administration has to finish its own investigation within six months.

The blast is not the first incident for Antero Resources in West Virginia. In August 2012, three workers at one of the company's wells in Harrison County were injured when methane from several hundred feet below ground ignited and caused a fire on the drilling rig floor. The DEP found that Antero had failed to maintain well control at the pad near Sycamore in that incident.