The impact of horizontal drilling and hydraulic fracturing on groundwater quality in the Cline shale play is not believed to be permanent, new research from the University of Texas at Arlington (UTA) suggests.
The research is the first to analyze the groundwater quality in the Cline shale region of West Texas before, during and after the expansion of unconventional exploration and production. Researchers found that water samples from private wells contained chlorinated solvents, alcohols and aromatic compounds exclusively after multiple unconventional oil wells had been activated within 3.1 miles (5 km) of the sampling sites. Large fluctuations in pH and total organic carbon levels also were detected in addition to a gradual accumulation of bromide.
These changes and levels are abnormal for typical groundwater quality, said Kevin Schug, the study’s lead author and UTA’s Shimadzu Distinguished Professor of Analytical Chemistry and director of UTA’s Collaborative Laboratories for Environmental Analysis and Remediation (CLEAR), in an April 26 press release. However, the results also suggest that containment from unconventional drilling may be variable and sporadic, not systematic, and that some toxic compounds associated with areas of high unconventional drilling may degrade or become diluted within the aquifer over time. The study also indicated that contamination pathways are complex; various toxic compounds were detected in groundwater seemingly at random times in areas of high drilling activity.
Schug said that more research is needed to precisely quantify and understand contamination cycles as well as to understand aquifer resilience to pollutants.
“A collaborative effort with an oil and gas industry leader would better help us trace these occurrences, as well as focus on understanding the fate of specific recipes of proprietary chemicals,” said Schug.
Schug told Rigzone that they have not worked in the past with industry partners.
“We have been very careful about who our partners have been, because we wanted to make sure our stance as neutral scientists was not compromised by any associations,” Schug said. “Now that we have established ourselves as neutral and unbiased, we believe a promising path forward would be to collaborate with an industry partner to time sample with different parts of the unconventional oil and gas development process.
To conduct the study, UTA researchers gathered and analyzed private water well samples on the eastern shelf of the Permian Basin four times during a 13-month period. They analyzed the samples for basic water quality, metal ions, organic ions and other chemicals, UTA said in an April 26 press statement. Schug said the samples were taken between December 2012 and January 2014.
The research paper was published April 26 in the journal, “Science of the Total Environment.” UTA partnered with the University of North Texas, Baylor University and sampling firm Inform Environmental LLC to conduct the research. The work supports UTA’s focus on research with global environmental impact, one of the four core themes of UTA’s Strategic Plan 2020: Bold Solutions/Global Impact.
CLEAR is running multiple research projects intended to help the scientific community, the industry, and most importantly, the public, understand the potential effects of unconventional oil and gas development on the environment, Schug said.
“We are dealing with complex processes in complex and variable environments,” said Schug. “It is our goal to develop and apply methods that provide reliable information about a wide variety of chemical constituents.”
Last year, UTA published a comprehensive study of potential groundwater contamination in the Barnett shale play in North Texas. That study of 550 water samples from public and private water wells found elevated levels of 10 different metals as well as 19 different chemicals compounds, including BTEX (benzene, toluene, ethyl benzene and xylenes) compounds, associated with hydraulic fracturing. The research also found elevated levels of methanol and ethanol, according to a UTA June 16, 2015 press release.
“These data do not necessarily identify unconventional oil and gas activities (UOG) as the source of the contamination; however, they do provide a strong impetus for further monitoring and analysis of groundwater quality in this region as many of the compounds we detected are known to be associated with UOG techniques,” the study authors said in the 2015 press release.
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