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martes, 21 de octubre de 2014

nsf.gov - National Science Foundation - New tracers can identify frac fluids in the environment.

Hola amigos: A VUELO DE UN QUINDE EL BLOG., hemos recibido la información de la Fundación Nacional de Ciencia de Los Estados Unidos, que nos dice:...".Los científicos han desarrollado nuevos trazadores geoquímicos que pueden identificar los fluidos de flujo de retorno de fracturación hidráulica que se han derramado o liberado en el medio ambiente.....
Los trazadores han sido probados en el campo en un lugar del derrame en West Virginia y aguas abajo de una planta de tratamiento de aguas residuales salmuera petróleo y gas en Pennsylvania....
"Al caracterizar las huellas isotópicas y geoquímicas de boro enriquecido y de litio en agua el flujo de retorno de la fracturación hidráulica, ahora podemos realizar un seguimiento de la presencia de fluidos 'frack" en el medio ambiente y distinguirlas de las aguas residuales procedentes de otras fuentes, incluidos los pozos de petróleo y gas convencionales , " dijo el geoquímico de la Universidad de Duke Avner Vengosh, quien co-dirigió la investigación......................

Scientists develop new geochemical tracers, tested at sites in West Virginia and Pennsylvania

Acid mine drainage flowing through a stream in western Pennsylvania forest.
Acid mine drainage flows through a stream in western Pennsylvania.
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October 20, 2014
Scientists have developed new geochemical tracers that can identify hydraulic fracturing flowback fluids that have been spilled or released into the environment.
The tracers have been field-tested at a spill site in West Virginia and downstream from an oil and gas brine wastewater treatment plant in Pennsylvania.
"By characterizing the isotopic and geochemical fingerprints of enriched boron and lithium in flowback water from hydraulic fracturing, we can now track the presence of 'frack' fluids in the environment and distinguish them from wastewater coming from other sources, including conventional oil and gas wells," said Duke University geochemist Avner Vengosh, who co-led the research.
"This gives us new forensic tools to detect if frack fluids are escaping into our water supply and what risks, if any, they might pose."
Using the tracers, scientists can determine where frack fluid contamination has--or hasn't--been released to the environment and, ultimately, help identify ways to improve how shale gas wastewater is treated and disposed of.
The researchers published their findings today in the journal Environmental Science & Technology. Their study, which was funded by the National Science Foundation (NSF), is the first to report on the development of the boron and lithium tracers.
"With increasing exploitation of unconventional oil and gas reservoirs through the use of hydraulic fracturing, it's important that we are able to assess the extent of hydraulic fracturing fluids entering the environment," said Alex Isern, section head in NSF's Division of Earth Sciences, which funded the research.
"This work is critical as it demonstrates that geochemical fingerprinting provides a powerful tool to differentiate potential sources of contamination and therefore guide efforts to mitigate environmental impacts."
Adds Nathaniel Warner of Dartmouth College, lead author of the paper, "This new technology can be combined with other methods to identify specific instances of accidental releases to surface waters in areas of unconventional drilling.
"It could benefit industry as well as federal and state agencies charged with monitoring water quality and protecting the environment."
Hydraulic fracturing fluids--or frack fluids--typically contain mixes of water, proprietary chemicals and sand. Mixtures can vary from site to site.
Drillers inject large volumes of the fluids down gas wells at high pressure to crack open shale formations deep underground and allow natural gas trapped within the shale to flow out and be extracted.
After the shale has been fractured, the frac fluids flow back up the well to the surface along with the gas and highly saline brines from the shale formation.
Some people fear that toxic frack fluid chemicals in this flowback could contaminate nearby water supplies if they're accidentally spilled or insufficiently treated before being disposed of.
"The flowback fluid that returns to the surface becomes a waste that needs to be managed," Vengosh explained.
"Deep-well injection is the preferable disposal method, but injecting large volumes of wastewater into deep wells can cause earthquakes in sensitive areas and is not geologically available in some states.
"In Pennsylvania, much of the flowback is now recycled and reused, but a significant amount of it is still discharged into local streams or rivers."
It's possible to identify the presence of frack fluid in spilled or discharged flowback by tracing synthetic organic compounds that are added to the fluid before it's injected down a well, Vengosh said, but the proprietary nature of these chemicals, combined with their instability in the environment, limits the usefulness of such tracers.
By contrast, the new boron and lithium tracers remain stable in the environment.
"The difference is that we are using tracers based on elements that occur naturally in shale formations," Vengosh said.
When drillers inject frack fluids into a shale formation, they not only release hydrocarbon, but also boron and lithium that are attached to clay minerals in the formation.
As the fluids react and mix at depth, they become enriched in boron and lithium.
As they're brought back to the surface, they have distinctive fingerprints that are different from other types of wastewater, including wastewater from a conventional gas or oil well, and from naturally occurring background water.
"This type of forensic research allows us to clearly identify possible sources of wastewater contamination," Vengosh said.
Thomas Darrah of The Ohio State University, Robert Jackson of Duke and Stanford Universities and Romain Millot and Wolfram Kloppmann of the French Geological Survey also co-authored the paper, which was partly funded by the Park Foundation.
Media Contacts Cheryl Dybas, NSF, (703) 292-7734, cdybas@nsf.gov
Tim Lucas, Duke University, (919) 613-8084, tdlucas@duke.edu
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2014, its budget is $7.2 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.
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image showing an unconventional shale gas drilling site in West Virginia.
An image showing an unconventional shale gas drilling site in West Virginia.
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Photo of unconventional shale gas well site northeastern Pennsylvania.
An unconventional shale gas well in northeastern Pennsylvania.
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An unconventional shale gas well in West Virginia.
An unconventional shale gas well in West Virginia.
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Wastewater tanks at a spill site in West Virginia.
Wastewater tanks at a spill site in West Virginia.
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A disposal site in western Pennsylvania. showing a stream, a forest and two people
A disposal site in western Pennsylvania.
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The National Science Foundation (NSF)
Guillermo Gonzalo Sánchez Achutegui
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