Tool to detect ‘frac fluids’

Spring flowers blossom in an arid landscape near Laingsburg in the Karoo October 11, 2013. Stretching across the heart of South Africa, the Karoo has stirred emotions for centuries, a stunning semi-desert wilderness fit mainly for artists, hunters and the toughest of farmers. It is now rousing less romantic passions. If energy companies and the ruling African National Congress (ANC) get their way, it will soon be home to scientists and geologists mapping out shale gas fields touted as game-changers for Africa's biggest economy, and working out whether fracking will work here. Picture taken October 11, 2013. To match Insight SAFRICA-FRACKING/ REUTERS/Mike Hutchings (SOUTH AFRICA - Tags: ENVIRONMENT ENERGY BUSINESS SOCIETY) ATTENTION EDITORS: PICTURE 03 OF 26 FOR PACKAGE 'SOUTH AFRICA - WATER, WEALTH AND FRACKING' TO FIND ALL IMAGES SEARCH 'FRACKING HUTCHINGS'

Spring flowers blossom in an arid landscape near Laingsburg in the Karoo October 11, 2013. Stretching across the heart of South Africa, the Karoo has stirred emotions for centuries, a stunning semi-desert wilderness fit mainly for artists, hunters and the toughest of farmers. It is now rousing less romantic passions. If energy companies and the ruling African National Congress (ANC) get their way, it will soon be home to scientists and geologists mapping out shale gas fields touted as game-changers for Africa's biggest economy, and working out whether fracking will work here. Picture taken October 11, 2013. To match Insight SAFRICA-FRACKING/ REUTERS/Mike Hutchings (SOUTH AFRICA - Tags: ENVIRONMENT ENERGY BUSINESS SOCIETY) ATTENTION EDITORS: PICTURE 03 OF 26 FOR PACKAGE 'SOUTH AFRICA - WATER, WEALTH AND FRACKING' TO FIND ALL IMAGES SEARCH 'FRACKING HUTCHINGS'

Published Oct 24, 2014

Share

Cape Town - Scientists have developed a geochemical tracer which can identify whether the fluids used in shale gas fracking – which include toxic chemicals – have been released into the surrounding environment and the water supply.

In a paper published this week in Environmental Science and Technology the researchers said it gave them a forensic tool to detect if “frac fluids” – the mixture of water, sand and chemicals used in fracking – had contaminated water supplies.

Co-lead author Avner Vengosh, a geochemist at Duke University in the US, said that by characterising the isotopic and geochemical fingerprints of enriched boron and lithium in the flowback water from fracking, it was possible to track the presence of frac fluids in the environment – and to distinguish them from wastewater from other sources.

Vengosh said it was possible to identify the presence of frac fluid in spills or flowbacks by tracing synthetic organic compounds that were added to the fluid before it was injected down a fracking well. But as gas companies kept the nature of the chemicals secret, plus their instability in the environment, the usefulness of this method was limited.

However, the new boron and lithium tracers remained stable in the environment.

“The difference is we are using tracers based on elements that occur naturally in shale formations,” Vengosh said.

When gas companies frack for shale gas, they inject water, sand and frac fluids at high pressure into the shale formation. This cracks open the shale deep underground, releasing gas, oil or water into the cracks created, and allows the gas to flow out and be extracted. The gas flows up to storage tanks with the water that comes back up.

Drillers release not only gas, but also boron and lithium that are attached to clay minerals in the shale. Vengosh said as the fluids react and mix deep underground, they become enriched in boron and lithium.

When they are brought back to the surface, they have distinctive isotopic fingerprints different from other types of wastewater, including wastewater from conventional gas or oil wells, and from the naturally occurring ground water.

“This type of forensic research allows us to clearly delineate between the possible sources of wastewater contamination,” Vengosh said.

One of the fears about fracking is contamination of ground or surface water with the toxic chemicals used in the fracking process. Some of the chemicals used are highly toxic to humans.

The wastewater that comes back to the surface has to be managed.

Vengosh said one method of disposal of the fracking waste was to inject it into deep underground wells.

“Injecting large volumes of wastewater into deep wells can cause earthquakes in sensitive areas, and is not geologically available in some areas. 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.”

Related Topics: