Toxic biocides, surfactants, corrosion inhibitors, and slicking agents are some of many types of chemicals used to extract oil and gas from shale and rock. The chemicals aid in extraction, but what happens after a spill?
Scientists from Colorado State University looked into 838 hydraulic fracturing fluid spills that took place in Colorado in order to better understand the chemistry beneath the surface. The spills ranged from five barrels of fluid within a well pad to spills larger than one barrel outside of a well pad.
The research team investigated how the degradation of the spilled chemicals is affected by co-contamination and will eventually carry out experiments on real spill sites. Reactors were used as models to portray chemical reactions as well as the biodegradation of hydraulic fracturing chemicals spilled in soil.
The scientists experimented with particular organic chemicals found in common hydraulic fracturing applications, the surfactant, polyethylene glycol (PEG); the biocide that fights microbial-caused pipe corrosion, glutaraldehyde; and the slicking agent that increases penetrating abilities in shale, polyacrylamide.
It was important to find out how the chemicals interacted together in addition to how the chemicals interacted with natural salts found underground. It turns out that PEG biodegrades in about 70 days, but in the presence of glutaraldehyde it remains in the soil for longer. In the presence of salt concentrations equal to those in hydraulic fracturing operations, PEG did not degrade.
The study of glutaraldehyde’s degradation cycle which totaled to almost two months led to another finding. Polyacrylamide remained in the soil for six months and was able to covalently bond to glutaraldehyde and bring down its toxic properties.
The environmental research is promising but still needs additional study into the relevant chemical interactions.