Colorado State University researchers have developed an analytical technique and database to identify whether chemical compounds called surfactants originated from hydraulic fracturing or other sources such as wastewater treatment plants.
Thomas Borch, a professor of environmental soil chemistry, and Jens Blotevogel, a research professor of environmental engineering, say the technique is novel and believe it is the first time scientists have been able to “fingerprint” these compounds.
“Now that we can identify these complex surfactant mixtures, we can better understand how these compounds move and under what conditions they may change into something else and how that may affect our environment,” Borch said.
The findings and the technique, which they developed in conjunction with researchers at University of Colorado-Boulder, are described in a paper entitled “Analysis of Hydraulic Fracturing Flowback and Produced Waters Using Accurate Mass: Identification of Ethoxylated Surfactants” published in the prestigious journal, Analytical Chemistry. The study was funded by The Borch-Hoppess Fund for Environmental Contaminant Research.
What are surfactants?
Surfactants are ubiquitous compounds. Manufacturers use them in ordinary household products such as detergents, shampoos and soaps because they reduce surface tension between oils and water. These compounds are what enable water to disperse and wash away dirt and grease.
Surfactants also are used during hydraulic fracturing, a process in which a mixture of water, sand and chemicals are forcefully injected into a well to break rock and enhance oil and gas extraction. They are just one group of the chemicals used in hydraulic fracturing. Oil and gas companies mix a variety of chemicals and each generally has its own proprietary “recipe.”
Concerns about groundwater contamination from fracturing fluids have prompted the state of Colorado to require oil and gas companies to disclose the list of chemicals they use. Most oilfield service companies do not describe the exact details of each chemical and only list them by generic terms.
One of the chemical mixtures that appears regularly is nonionic, ethoxylated surfactants – the same compound group that are used in household detergents and cleaners (usually labeled as “polyethylene glycol”).
Why study surfactants?
Borch and Blotevogel say there is a real need to differentiate the sources of these surfactants – be it hydraulic fracturing or a wastewater plant.
The impact of hydraulic fracturing on groundwater is an increasingly controversial topic.
This technique is a step to better understanding that impact, they say, and also what happens to surfactants once they are injected underground in hydraulic fracturing fluid.
No one is sure what happens to them when they are exposed to the high-temperature, high-pressure environment of oil- and gas-bearing geological formations thousands of feet underground.
“We don’t know if they change into something else and if parts stay within the shale or if it returns with flowback (water that returns back up from fracturing) or mixes with produced waters (the water that occurs naturally in the fractured geologic formation),” Borch said.
Borch and Blotevogel believe the technique, which essentially identifies the chemical “fingerprints,” could aid those charged with monitoring water quality and even remediation efforts. They said it also could help oil and gas companies understand if they are using too much of these compounds or too little, and how effective they are.
“There are lot of applications,” Borch said.