Spate of gas drilling leaks raises Marcellus concerns
PA DEP
“Stable isotopes help us to narguish three broad sources, As Pennsylvania and other eastern row the focus of our investigations according to isotope pioneer states prepare for a rush of new by ruling out some sources. Then Dennis Coleman at Isotech drilling associated with the Marwe go to the potential source and Laboratories, Inc. These are: cellus Shale, gas leaks are utilize other investigative techthermogenic gas from geological prompting questions about niques to confirm the source of the formations; “drift gas” formed whether these states are prepared. stray gas,” says Baldassare, who by microbial breakdown in shalOn New Year’s Day, 2009, in the coauthored a study with the U.S. low, unconsolidated deposits; tiny northeast Pennsylvania town Geological Survey that traced of Dimock, a drinking-water stray gas to a leaking underwell blew up because of a ground storage system and is methane leak associated with involved in organizing a Nonatural-gas drilling nearby. vember stray-gas workshop. In the spring, high levels of The recent leaks are related methanesa result of a poorly to flaws in cement, well cascased gas wellswere found ing, or overpressurization of in water supplies in the town the casing. PA DEP is in the of Bradford; in late July, one process of tightening policies home near Roaring Brook that apply to these issues, was evacuated, and alternaaccording to spokesperson tive sources of drinking water Teresa Candori. were provided when high gas A source who has 30 years pressure at another well of experience in the public caused a leak. In May 2003, a natural-gas explosion injured two Natural-gas leaks are rela- people in suburban Pittsburgh. Stable isotopes helped and private sectors tells ES&T that the regulations need some tively common in Pennsylva- identify a leaking gas well casing as the source. changes, but “the problem is nia, which employs a fulland gas formed by bacterial degnot enough inspectors. Wells get time geologist to investigate such radation (e.g., in wetlands or boinspected only once, and many inincidents. In recent years, some of vine digestive systems). spectors don’t have enough experithese leaks have had devastating Tracing the leak can also be ence,” the source says. consequences, including home highly contentious, as in the case A recent study of state regulaexplosions and fatalities, accordof the hydraulic fracturing wells tions across the country found ing to an investigation by ProPubdrilled into the Marcellus formathat most states have standards lica, Inc., an independent tion at Dimock. In February 2009, specifying the use of concrete to nonprofit newsroom. Leaks are PA DEP cited the drilling comprotect aquifers, but many, inmainly a legacy of the state’s fospany Cabot Oil & Gas Corp. for cluding Pennsylvania, do not resil fuel drilling and mining hisviolations of the state’s Clean quire testing to show that the tory; however, leaks from Streams Law with respect to the concrete is strong enough for the operating wells have caused exDimock explosion. Cabot contask. Congressional proposals call plosions and even fatalities. tends that methane in drinkingfor changes in such regulations. Tracing the leaks is difficult, water wells is a historical problem Given the promise and peril of because sources include gas wells, locally and that drilling may not the coming drilling boom, few natural-gas storage fields, pipebe the cause, according to knowledgeable people are willing lines, coal mines, and landfillssall spokesperson Kenneth Komorosto talk on the record. But, says one of which can be either active or ki. But stable-isotope analysis inexperienced geologist, “Deep horiabandoned. Bacterial degradation dicates that the gas in drinkingzontal drilling and hyrdaulic fracof organic matter also produces water wells is geological. The turing don’t have a track record in methane. Stable-isotope analysis additional presence of heavier hythe northeast. Pennsylvania and is an essential tool for identifying drocarbons, ethane, propane, and New York aren’t Texas. Our geology the source, according to Pennsylbutane supports this. Drift gas, is more complex, our rocks have vania Department of Environmenwhich commonly occurs in low been through more deformation. tal Protection (PA DEP) geologist concentrations near the surface, is Companies and regulators need to Fred Baldassare, who investigates not the culprit, says Baldassare. tread carefully.” stray gas leaks. “The isotopes and the heavier hyThe carbon and hydrogen iso—REBECCA RENNER drocarbons nail it,” he adds. topic ratios in methane distin10.1021/es9025563
2009 American Chemical Society
Published on Web 09/02/2009
October 15, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 7599
