Source: Dow Jones News Service, September 15, 2014
Posted on: http://fpn.advisen.com
Natural gas is contaminating some aquifers not from hydraulic fracturing but from faulty well preparation, according to a new paper.
Poorly built and cemented gas wells, rather than fracking itself, have allowed contaminants to flow into shallow drinking-water sources, according to a report published in the Proceedings of the Natural Academy of Sciences.
A debate has raged for years over whether the U.S. energy boom is fouling aquifers and water wells–and what can be done about it.
Researchers reported Monday that they developed a tool that can identify whether underground gas has migrated toward the surface over time, or whether it moved recently and rapidly up an industry-drilled well or the cement surrounding the well pipe. Fracking involves pushing a slurry of water, sand and chemicals down a well to break up dense rocks and coax more fuel from the ground.
Many academics and some industry engineers have long argued that when contamination occurs, it is the result of bad well construction not the fracking process. Others in the energy industry have maintained that natural gas has been found in aquifers and water wells for years and that there is no proof that fracking or other drilling has made it worse.
“Where contamination occurs, it related strictly to well integrity,” said study co-author Thomas Darrah, an assistant professor at Ohio State University. “The answer is not to stop drilling. The fix is better executions on the construction of the well and improving well integrity.” He said evidence of contamination didn’t correlate to wholesale leaks caused by fracking.
Michael Krancer, a former Pennsylvania secretary of environmental protection, expressed skepticism that there could be any simple, uncontested way to determine the provenance of natural gas. “What people are expecting–and they are not going to get–is a pregnancy test. It is much more complicated than that,” said Mr. Krancer, now head of the energy group at law firm Blank Rome LLP.
The authors of the study, funded by National Science Foundation and Duke University, said their new means of fingerprinting natural gas uses concentrated inert noble gases such as helium and argon to determine whether gas in an aquifer has been there for decades or appeared only recently, flowing up through man-made wells bored into shale rock.
“We have developed a tool that can be employed for detecting the source of contamination,” said study co-author Avner Vengosh, a Duke University geochemistry professor.
The study said the new process showed that poorly built and cemented gas wells have caused contamination in eight clusters: seven in northeastern Pennsylvania and one near Fort Worth, Texas. The study didn’t address how common well-integrity failure is, or what level of gas in an aquifer made the water unsafe.
Energy in Depth, a group funded by the Independent Petroleum Association of America, said the science needs further review. “I don’t think you are going to find anyone in the industry who disagrees with the importance of well integrity and constructing wells properly,” said spokesman Steve Everley.
Gas might be naturally occurring and without more confirmation, state officials might impose costly changes for oil producers–such as requiring new tests to make sure cement around wells is solid–and still face the problem of methane in aquifers, he said.