Water resource impacts during unconventional shale gas development: The Pennsylvania experience

Brantley, Susan L.; Yoxtheimer, David; Arjmand, S.; Grieve, Paul L.; Vidic, Radisav D.; Pollak, Jonathan; Llewellyn, Garth T.; Abad, J. D.; Simon, Cesar

doi:10.1016/j.coal.2013.12.017

Cited by 258 publications

(308 citation statements)

References 22 publications

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“…Conservative inorganic constituents (e.g., Cl and Br) can be used to determine if flowback or production waters have contaminated groundwater because these wastewaters can contain total dissolved solids in concentrations greater than 300,000 mg/L (6, 18). Further, if upward migration of HVHF fluids occurred after mixing with formation waters, dissolved Cl/Br mass ratios are more likely to be useful as effective fingerprints than the HVHF fluid components themselves, due to their more conservative behavior in groundwater (6,10). Crossplots of Cl/Br (mass ratio) versus Cl concentration (Fig.…”

Section: Resultsmentioning

confidence: 99%

Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development

Llewellyn¹,

Dorman²,

Westland³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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High-volume hydraulic fracturing (HVHF) has revolutionized the oil and gas industry worldwide but has been accompanied by highly controversial incidents of reported water contamination. For example, groundwater contamination by stray natural gas and spillage of brine and other gas drilling-related fluids is known to occur. However, contamination of shallow potable aquifers by HVHF at depth has never been fully documented. We investigated a case where Marcellus Shale gas wells in Pennsylvania caused inundation of natural gas and foam in initially potable groundwater used by several households. With comprehensive 2D gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS), an unresolved complex mixture of organic compounds was identified in the aquifer. Similar signatures were also observed in flowback from Marcellus Shale gas wells. A compound identified in flowback, 2-n-Butoxyethanol, was also positively identified in one of the foaming drinking water wells at nanogram-per-liter concentrations. The most likely explanation of the incident is that stray natural gas and drilling or HF compounds were driven ∼1–3 km along shallow to intermediate depth fractures to the aquifer used as a potable water source. Part of the problem may have been wastewaters from a pit leak reported at the nearest gas well pad—the only nearby pad where wells were hydraulically fractured before the contamination incident. If samples of drilling, pit, and HVHF fluids had been available, GCxGC-TOFMS might have fingerprinted the contamination source. Such evaluations would contribute significantly to better management practices as the shale gas industry expands worldwide.

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Section: Resultsmentioning

confidence: 99%

Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development

Llewellyn¹,

Dorman²,

Westland³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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257

241

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“…To unambiguously address such concerns, it is essential to assess the natural occurrence of methane and its spatial distribution, the variability of methane concentrations and the sources of methane in shallow groundwater prior to unconventional energy development to establish a baseline. In the last 5 years, an increasing number of publications have addressed the questions of occurrence and sources of methane in shallow groundwater in natural gas producing regions (Osborn et al, 2011a, b;Warner et al, 2013;Darrah et al, 2012Darrah et al, , 2014Molofsky et al, 2013;Siegel et al, 2015;Vengosh et al, 2013;Brantley et al, 2014;Baldassare et al, 2014;McPhilips et al, 2014;McIntosh et al, 2014;Vidic et al, 2013;Hamilton et al, 2015). These studies have contributed a wealth of baseline data for gas occurrences in shallow groundwater in many regions of North America.…”

Section: Introductionmentioning

confidence: 99%

Redox controls on methane formation, migration and fate in shallow aquifers

Humez¹,

Mayer²,

Nightingale³

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. Development of unconventional energy resources such as shale gas and coalbed methane has generated some public concern with regard to the protection of groundwater and surface water resources from leakage of stray gas from the deep subsurface. In terms of environmental impact to and risk assessment of shallow groundwater resources, the ultimate challenge is to distinguish (a) natural in situ production of biogenic methane, (b) biogenic or thermogenic methane migration into shallow aquifers due to natural causes, and (c) thermogenic methane migration from deep sources due to human activities associated with the exploitation of conventional or unconventional oil and gas resources. This study combines aqueous and gas (dissolved and free) geochemical and isotope data from 372 groundwater samples obtained from 186 monitoring wells of the provincial Groundwater Observation Well Network (GOWN) in Alberta (Canada), a province with a long record of conventional and unconventional hydrocarbon exploration. We investigated whether methane occurring in shallow groundwater formed in situ, or whether it migrated into the shallow aquifers from elsewhere in the stratigraphic column. It was found that methane is ubiquitous in groundwater in Alberta and is predominantly of biogenic origin. The highest concentrations of biogenic methane ( > 0.01 mM or > 0.2 mg L −1 ), characterized by δ 13 C CH 4 values < −55 ‰, occurred in anoxic Na-Cl, Na-HCO 3 , and Na-HCO 3 -Cl type groundwaters with negligible concentrations of nitrate and sulfate suggesting that methane was formed in situ under methanogenic conditions for 39.1 % of the samples. In only a few cases (3.7 %) was methane of biogenic origin found in more oxidizing shallow aquifer portions suggesting limited upward migration from deeper methanogenic aquifers. Of the samples, 14.1 % contained methane with δ 13 C CH 4 values > −54 ‰, potentially suggesting a thermogenic origin, but aqueous and isotope geochemistry data revealed that the elevated δ 13 C CH 4 values were caused by microbial oxidation of biogenic methane or postsampling degradation of low CH 4 content samples rather than migration of deep thermogenic gas. A significant number of samples (39.2 %) contained methane with predominantly biogenic C isotope ratios (δ 13 C CH 4 < −55 ‰) accompanied by elevated concentrations of ethane and sometimes trace concentrations of propane. These gases, observed in 28.1 % of the samples, bearing both biogenic (δ 13 C) and thermogenic (presence of C 3 ) characteristics, are most likely derived from shallow coal seams that are prevalent in the Cretaceous Horseshoe Canyon and neighboring formations in which some of the groundwater wells are completed. The remaining 3.7 % of samples were not assigned because of conflicting parameters in the data sets or between replicates samples. Hence, despite quite variable gas concentrations and a wide range of δ 13 C CH 4 values in baseline groundwater samples, we found no conclusive evidence for deep thermogenic gas migration into shallow aqu...

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“…3. Consideration of the possible analysis of additional parameters, including other indicator elements or isotope ratios (Brantley et al 2014, Chapman et al 2012, once the wells are active. 4.…”

Section: Discussionmentioning

confidence: 99%

“…Other potential environmental effects include contamination of groundwater through poor casing of well bores (Ingraeffea et al 2014); air pollution from transport vehicles, compressor stations, pipelines, and well pad activities (Caulton et al 2014); and fragmentation of sensitive lands due to pipeline and infrastructure construction (Abrahams et al 2015;Drohan et al 2012). Because the extraction activities are occurring over a very large and remote geographic area in Pennsylvania and because spill events can be quite ephemeral, the documentation of these impacts is extremely challenging (Brantley et al 2014). In this knowledge landscape of scarce data and controversial environmental threats (Bowen et al 2015;Entrekin et al 2011;Vidic et al 2013), the unprecedented rapid growth of the shale gas extraction industry in Pennsylvania has motivated concerned citizens to seek ways to help fill data gaps and contribute to sound evidence for public policy decisions.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Marcellus: A Case Study of a Collaborative Volunteer Monitoring Project to Document the Impact of Unconventional Shale Gas Extraction on Small Streams

Wilderman

Monismith

2016

CSTP

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The rapid growth of the natural gas extraction industry in Pennsylvania and neighboring states has stirred concerned citizens to seek ways to collect data on water quality impacts from the extraction activities. As a response to requests from community members, the Alliance for Aquatic Resource Monitoring (ALLARM) developed a volunteer-friendly protocol in 2010 for early detection and reporting of surface water contamination by shale gas extraction activities in small streams. To date, ALLARM has trained more than 2,000 volunteers in Pennsylvania, New York, and West Virginia to monitor water quality (conductivity, barium, strontium, and total dissolved solids) and physical parameters (stream stage and visual observations) prior to, during, and after shale gas wells have been developed. This paper documents the operational models of Public Participation in Scientific Research (PPSR) used by ALLARM, describes the volunteer monitoring protocol developed, and examines three years of water quality results from hundreds of monitoring sites in Pennsylvania and New York.The majority of watersheds monitored are small, forested, headwater streams. Results indicate that mean conductivity in streams is strongly and positively related to the percentage of development and the percentage of limestone in the watersheds. Mean conductivity is not significantly related to number or density of drilled wells, although the dataset did not lend itself to finding a signal from shale gas activities because only 20% of the watersheds had wells drilled at the time of sampling. This fact enables the use of these data as baseline data for future documentation of shale gas impacts on water quality. Volunteers have reported multiple cases of visual pollution related to shale gas activities, but have not identified water contamination events based on stream water chemistry.The results of the volunteer dataset are compared with results from the scientific literature, affirming the credibility and usefulness of the data. Some lessons learned from this project include: The importance of strong and timely support to volunteers to ensure accurate reporting in real-time; the unique role that citizen scientists can play in a rural landscape where well sites are remote and government oversight is not practical; and the importance of customizing a PPSR operational model to fit the goals and scale of the project.Recommendations for continued collection and analysis of data include: 1) develop and implement an intentional study design to monitor those watersheds that now have baseline data once drilling begins, 2) target watersheds whose characteristics are under-represented in this dataset, 3) consider the analysis of additional parameters and the monitoring of high risk systems, 4) develop a central, user-friendly database for volunteers to submit their own data and receive preliminary analyses, and 5) partner with other volunteer data collectors to collaborate with data analysis and interpretation.

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Water resource impacts during unconventional shale gas development: The Pennsylvania experience

Cited by 258 publications

References 22 publications

Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development

Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development

Redox controls on methane formation, migration and fate in shallow aquifers

Monitoring Marcellus: A Case Study of a Collaborative Volunteer Monitoring Project to Document the Impact of Unconventional Shale Gas Extraction on Small Streams

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