Repository for Oil and Gas Energy Research (ROGER)

Abstract:
The potential for shale gas development (SGD) in South Africa’s environmentally sensitive Karoo region has attracted the interest of energy companies, government and the public. The South African government is eager to revive economic growth, improve energy security following an energy supply crisis and relieve high unemployment. The public is torn between environmental concerns and prospects of economic benefits, while investors seek clarity in legislation. The impact of the US shale revolution explains the allure of SGD and constitutes the only model worldwide of a developed shale industry. South Africa is a useful case study for examining how various societal interests shape support for and opposition to SGD. While government seeks to proceed with exploration, a dominant coal industry and other alternatives including renewables and nuclear compete for attention, and there are increasing concerns about the size and economic viability of South Africa’s shale gas deposits. Influential actors in the energy-intensive industries comprising South Africa’s powerful ‘minerals-energy complex’ will play a role in how any shale industry might develop. By considering the interests of key actors including a vacillating government, cautious energy companies and a determined environmental lobby, this article examines South Africa’s tenuous road towards SGD.

Abstract:
Environmental and community factors may influence the development or course of depression and sleep problems. We evaluated the association of unconventional natural gas development (UNGD) with depression symptoms and disordered sleep diagnoses using the Patient Health Questionnaire-8 and electronic health record data among Geisinger adult primary care patients in Pennsylvania. Participants received a retrospective metric for UNGD at their residence (very low, low, medium, and high) that incorporated dates and durations of well development, distance from patient homes to wells, and well characteristics. Analyses included 4,762 participants with no (62%), mild (23%), moderate (10%), and moderately severe or severe (5%) depression symptoms in 2014–2015 and 3,868 disordered sleep diagnoses between 2009–2015. We observed associations between living closer to more and bigger wells and depression symptoms, but not disordered sleep diagnoses in models weighted to account for sampling design and participation. High UNGD (vs. very low) was associated with depression symptoms in an adjusted negative binomial model (exponentiated coefficient = 1.18, 95% confidence interval [CI]: 1.04–1.34). High and low UNGD (vs. very low) were associated with depression symptoms (vs. none) in an adjusted multinomial logistic model. Our findings suggest that UNGD may be associated with adverse mental health in Pennsylvania.

Abstract:
This research investigates the relation between water, energy, and transportation systems, using the growing hydraulic fracturing activity in the Eagle Ford shale play region of southwest Texas in which the local water systems and road infrastructure were not designed for the frequent transport of water into the production site and of produced gas and oil from the site as are often required for hydraulic fracturing. The research: 1) quantifies the interconnections between water, energy, and transportation systems specific to the Eagle Ford shale region; 2) identifies and quantifies the economic, social, and environmental indicators to evaluate scenarios of oil and gas production; and 3) develops a framework for analysis of the economic, societal, and long term sustainability of the sectors and 4) an assessment tool (WET Tool) that estimates several economic indicators: oil and natural gas production, direct and indirect tax revenues, and average wages for each scenario facilitates the holistic assessment of oil and gas production scenarios and their associated trade-offs between them. Additionally, the Tool evaluates these social and environmental indices, (water demand, emissions, water tanker traffic, accidents, road deterioration, and expected average employment times). Scale of production is derived from the price of oil and gas; government revenues from production fluctuations in relation to rise and fall of the oil and gas market prices. While the economic benefits are straightforward, the social costs of shale development (water consumption, carbon emissions, and transportation/infrastructure factors), are difficult to quantify. The tool quantifies and assesses potential scenario outcomes, providing an aid to decision makers in the public and private sectors that allows increased understanding of the implications of each scenario for each sector by summarizing projected outcomes to allow evaluation of the scenarios and comparison of choices and facilitate the essential dialogue between these sectors.

Abstract:
Microbial Ecology![Figure][1] Microbes increase methane output from shale gas wells. CREDIT: NAMTHIP MUANTHONGTHAE/SHUTTERSTOCK Microbes are thought to contribute to chemical processes that occur during hydraulic fracturing of shale. How these communities develop after injection of fracking

Abstract:
The rapid rise of shale gas development has triggered environmental and human health concerns due to its impacts on water resources, especially on disinfection byproduct (DBP) formation upon chlorination. Despite the recently reported results on bromide, the effects of non-bromide ions in production wastewater at extremely high levels are vaguely defined. In this study, we investigated the effects of production wastewater, with bromide and non-bromide species, on the formation of DBPs when production wastewater was spiked into surface waters at various percentages. Results showed that the introduction of debrominated production wastewater led to increased formation of some chlorinated DBP species in selected surface water and wastewater. As the spiking percentage of debrominated production wastewater increased, the chlorinated DBP species increased. The contributions of individual cations to DBP formation followed a sequence of magnesium > calcium > barium at 0.10% spiking percentage due to the different catalytic effects of their chelates with organic precursors. The study of anions suggested that the discharge of treated production wastewater containing elevated sulfate may further enhance DBP formation. The significance of this study lies in the fact that in addition to bromide concerns from production wastewater, non-bromide species also contributed to DBP formation. The gas production wastewater management decision should consider the negative impacts from both bromide and non-bromide species to better protect the receiving water resources.

Abstract:
Shale gas is likely to play a major role in China's transition away from coal. In addition to technological and infrastructural constraints, the main challenges to China's sustainable shale gas development are sufficient shale gas production, water availability, and adequate wastewater management. Here we present, for the first time, actual data of shale gas production and its water footprint from the Weiyuan gas field, one of the major gas fields in Sichuan Basin. We show that shale gas production rates during the first 12 months (24 million m3 per well) are similar to gas production rates in U.S. shale basins. The amount of water used for hydraulic fracturing (34,000 m3 per well) and the volume of flowback and produced (FP) water in the first 12 months (19,800 m3 per well) in Sichuan Basin are also similar to the current water footprints of hydraulic fracturing in U.S. basins. We present salinity data of the FP water (5000 to 40,000 mgCl/L) in Sichuan Basin and the treatment operations, which include sedimentation, dilution with fresh water, and recycling of the FP water for hydraulic fracturing. We utilize the water use data, empirical decline rates of shale gas and FP water productions in Sichuan Basin to generate two prediction models for water use for hydraulic fracturing and FP water production upon achieving China's goals to generate 100 billion m3 of shale gas by 2030. The first model utilizes the current water use and FP production data, and the second assumes a yearly 5% intensification of the hydraulic fracturing process. The predicted water use for hydraulic fracturing in 2030 (50–65 million m3 per year), FP water production (50–55 million m3 per year), and fresh water dilution of FP water (25 million m3 per year) constitute a water footprint that is much smaller than current water consumption and wastewater generation for coal mining, but higher than those of conventional gas production in China. Given estimates for water availability in Sichuan Basin, our predictions suggest that water might not be a limiting factor for future large-scale shale gas development in Sichuan Basin.

Abstract:
Incomplete information regarding emissions from oil and natural gas production has historically made it challenging to characterize the air quality or air pollution-related health impacts for this sector in the United States. Using an emissions inventory for the oil and natural gas sector that reflects information regarding the level and distribution of PM2.5 and ozone precursor emissions, we simulate annual mean PM2.5 and summer season average daily 8 h maximum ozone concentrations with the Comprehensive Air-Quality Model with extensions (CAMx). We quantify the incidence and economic value of PM2.5 and ozone health related effects using the environmental Benefits Mapping and Analysis Program (BenMAP). We find that ambient concentrations of PM2.5 and ozone, and associated health impacts, are highest in a handful of states including Colorado, Pennsylvania, Texas and West Virginia. On a per-ton basis, the benefits of reducing PM2.5 precursor emissions from this sector vary by pollutant species, and range from between $6,300 and $320,000, while the value of reducing ozone precursors ranges from $500 to $8,200 in the year 2025 (2015$).

Abstract:
Surface spills of water produced from hydraulic fracturing can expose soil and groundwater to organics such as BTEX and naphthalene (BTEX&N) as well as high concentrations of salt. As an alternative to soil excavation, we evaluated the effectiveness of BTEX&N soil remediation using 2 grasses present in Colorado. Perennial ryegrass and foxtail barley were grown separately in pots in the greenhouse and exposed to salt or a synthesized produced-water slurry containing relevant levels of salt and BTEX&N. Plant biomass was measured 14 days post-spill, and levels of BTEX&N were quantified using GC/MS for soil, roots, and shoots at day 7 and 14 post-spill. Foxtail barley shoot growth was limited by BTEX&N, whereas perennial ryegrass shoot growth was enhanced by salt but not BTEX&N. While BTEX&N in soil associated with foxtail barley mainly decreased over time, the soil associated with perennial ryegrass mainly saw an increase in BTEX&N with time. However, further research is needed to determine the fate of BTEX&N within grasses and soil.

Abstract:
For over four years, local residents, the government, industry and scientists have been anticipating the start of shale gas operations at a site at Preston New Road in Lancashire, North West England. This paper examines how these different social actors perceive and think about time, as well as the future of fracking. Many of their disagreements expose the diverging ways in which they make sense of time and point to time and temporality as a useful lens for understanding their respective rationalities. Time also emerges as a principal mode of experiencing inequality, because not all notions of time are equivalent in relation to power. The three dispositions towards time that are played out in the shale gas debate in Lancashire construct time as: owned, as being the same in every moment, and as having real social and environmental effects. This article analyses the politics of time, which is an arena in which these notions are articulated and negotiated, and where they compete for a hegemonic position with varying success. It concludes by arguing that inscribing the future with particular characteristics is a powerful tool that forecloses some arguments and creates power disparities in debates around unconventional resource extraction.

Abstract:
We conducted a large-scale assessment of unconventional oil and gas (UOG) development effects on brook trout (Salvelinus fontinalis) distribution. We compiled 2231 brook trout collection records from the Upper Susquehanna River Watershed, USA. We used boosted regression tree (BRT) analysis to predict occurrence probability at the 1:24,000 stream-segment scale as a function of natural and anthropogenic landscape and climatic attributes. We then evaluated the importance of landscape context (i.e., pre-existing natural habitat quality and anthropogenic degradation) in modulating the effects of UOG on brook trout distribution under UOG development scenarios. BRT made use of 5 anthropogenic (28% relative influence) and 7 natural (72% relative influence) variables to model occurrence with a high degree of accuracy [Area Under the Receiver Operating Curve (AUC) = 0.85 and cross-validated AUC = 0.81]. UOG development impacted 11% (n = 2784) of streams and resulted in a loss of predicted occurrence in 126 (4%). Most streams impacted by UOG had unsuitable underlying natural habitat quality (n = 1220; 44%). Brook trout were predicted to be absent from an additional 26% (n = 733) of streams due to pre-existing non-UOG land uses (i.e., agriculture, residential and commercial development, or historic mining). Streams with a predicted and observed (via existing pre- and post-disturbance fish sampling records) loss of occurrence due to UOG tended to have intermediate natural habitat quality and/or intermediate levels of non-UOG stress. Simulated development of permitted but undeveloped UOG wells (n = 943) resulted in a loss of predicted occurrence in 27 additional streams. Loss of occurrence was strongly dependent upon landscape context, suggesting effects of current and future UOG development are likely most relevant in streams near the probability threshold due to pre-existing habitat degradation.

Abstract:
More recent public discourse has taken place regarding the potential correlation between seismic activity and hydraulic fracturing in shale gas reservoirs. Public fears about the risk of seismicity stem mainly from past earthquakes induced by conventional deep injections because the two types of projects share similar mechanisms of rock failure and fault activation. Although previous earthquake risks associated with fluid injection were not serious, the situation would be far more problematic if hydraulic fracturing in a shale gas reservoir triggered a similar-sized earthquake due to potential environmental issues. In fact, almost all documented injection-induced earthquakes have been associated with long-duration and high-volume injection rather than short-term (hours) pressurization (e.g., hydraulic fracturing). In general, hydraulic fracturing operations mostly induce microseismic events through rock failure and activation of small fractures. Although shale reservoirs in tectonically active zones pose a high risk of inducing large-magnitude seismic activities, the internal geological conditions and external stimulation conditions are impossible to be satisfied simultaneously to trigger activation of an entire fault and to result in a destructive earthquake during hydraulic fracturing operations.

Abstract:
Model uncertainty analysis can quantify uncertainty both prior to calibration and postcalibration if the calibration dataset appropriately informs parameter estimates and model predictions. In certain cases calibration data (observations or measurements) may not be immediately apparent, but calibration datasets can be developed from related data for model interrogation and quantification and minimization of uncertainty. This study applies a series of techniques to investigate uncertainty in a simple numerical model of upward flow (leakage) through an abandoned oil and gas well converted into a water well in hydraulically fractured shale. Model calibration was achieved by developing a limited calibration dataset from well-specific measurements at a horizontal well in the Eagle Ford Shale play. Uncertainty in the calibrated model was interrogated using sensitivity, linear, and nonlinear analyses available in the PEST suite. Sensitivity analysis suggests that flowback after hydraulic fracturing could be crucial in reducing leakage. Linear analyses indicate horizontal-well production rates and long-term reservoir pressures are valuable measurements to collect when evaluating potential leakage. Nonlinear analyses identify the range in predictive uncertainty of potential leakage. The results underscore the need to evaluate and include additional types of well data in public records, such as flowback and produced water volumes. Overall, the results of this study illustrate the utility of uncertainty analyses with a limited calibration dataset applied to a simple model.

Abstract:
In recent years, there have been a number of studies assessing water chemistry in private water supply wells in areas of unconventional oil and gas development. Many of the wells in these studies were only sampled once and a question remains as to how representative the results from a single sample are given the potential for temporal variability. To evaluate this issue, the temporal variability of water chemistry from fourteen private water wells in two study areas of southeastern New Brunswick was monitored on a monthly basis over the course of a year. The study areas had been the focus of unconventional natural gas development (the Sussex study area) or exploration (the Kent study area). Temporal data for dissolved methane, ethane and propane concentrations, the stable isotopes of carbon and hydrogen in methane, and inorganic chemistry were collected. In the Kent study area, there was little variation in water chemistry from the six wells studied, with the relative standard deviations (RSD) for methane ranging from 0 to 20%. This indicates that the water from these wells was not affected by seasonal factors such as changing temperature or hydrogeological conditions and that it is possible to acquire reproducible dissolved methane concentrations and water chemistry data from private water supply wells. The drillers’ logs for the Kent wells indicate that the casings were installed to depths that likely isolated the water-producing intervals from near-surface hydrogeochemical variations and that the majority of water drawn from the wells enters from a single, relatively high-yield, water-bearing zone. The temporal variability was higher in the eight wells located in the Sussex study area, with the RSDs for methane ranging from 18 to 141%. There were concurrent variations in inorganic parameters, suggesting that the changes in methane concentrations reflected hydrogeochemical fluctuations in the aquifers as opposed to sampling artifacts. The wells with the most variable water chemistry over time had multiple, often relatively low-yield, water-bearing zones. In those wells, methane was associated with Na-HCO3 water from relatively deep water-bearing zones, while dissolved oxygen (DO) and NO3 were associated with shallower, Ca-HCO3, groundwater. The presence of the redox-controlled species Mn, Fe, SO4 and H2S, did not appear to affect the temporal variability of methane.

Abstract:
The USA has experienced a sudden expansion of oil and natural gas production due to the combination of hydraulic fracturing and horizontal drilling. The energy extraction boom has had many localized impacts, most notably in areas with substantial shale gas reserves. This paper exploits a natural experiment in the Marcellus region to examine one channel of the so-called resource curse, the effect of resource extraction on local crime. The results show that areas experiencing a natural gas extraction boom suffer an increase in overall violent crimes, while property crimes remain similar to non-boom areas. Furthermore, the violent crime increase appears to be driven primarily by increases in aggravated and sexual assaults.

Abstract:
Biophysical and socio-economic monitoring during unconventional oil and gas (UOG) extraction is important to assess change and to have reference conditions against which to identify UOG extraction activity impacts. The large-scale cumulative impacts of UOG extraction makes standardised monitoring across geographic and sociopolitical regions important. This article emphasises the importance of a robust monitoring framework that must serve as a guideline for planning monitoring activities during UOG extraction. A case study from South Africa is presented to illustrate important aspects to address during the development of a UOG extraction monitoring framework. The South African case is critically assessed and resultant policy implications are discussed. Important policy considerations include performing baseline monitoring during UOG extraction, performing UOG extraction monitoring in an integrated, systematic, and standardised manner, ensuring that proper resources are available to perform the monitoring and implementing an adaptive management plan that is linked to UOG extraction monitoring.

Abstract:
The study objective was to use a preliminary risk based framework to evaluate the sufficiency of existing air data to answer an important public health question in Colorado: Do volatile organic compounds (VOCs) emitted into the air from oil and gas (OG) operations result in exposures to Coloradoans living at or greater than current state setback distances (500 feet) from OG operations at levels that may be harmful to their health? We identified 56 VOCs emitted from OG operations in Colorado and compiled 47 existing air monitoring datasets that measured these VOCs in 34 locations across OG regions. From these data, we estimated acute and chronic exposures and compared these exposures to health guideline levels using maximum and mean air concentrations. Acute and chronic non-cancer hazard quotients were below one for all individual VOCs. Hazard indices combining exposures for all VOCs were slightly above one. Lifetime excess cancer risk estimates for benzene were between 1.0 x 10(-5)-3.6 x 10(-5) and ethylbenzene was 7.3 x 10(-6). This evaluation identified a small sub-set of VOCs, including benzene and n-nonane, which should be prioritized for additional exposure characterization in site-specific studies that collect comprehensive time-series measurements of community scale exposures to better assess community exposures.

Abstract:
On January 1, 2009, a concrete slab covering a water-pump vault of a water well 400 m north of a Marcellus gas well in Dimock, Pennsylvania, USA was reported to have split into three pieces while being overturned. It was suggested that the cycling on of a water pump sparked the deflagration of a methane-air mixture causing the slab to overturn. Here, the conditions necessary to generate an explosion consistent with evidence, mainly a split and overturned concrete slab unmarked by soot or other evidence of a flame, are analyzed. Using more than one approach, calculations show that the maximum pressure to lift the concrete slab was roughly 0.3 bar. Considering among others the flammable range of methane, the explosion pressure as a function of equivalence ratio, the presence of methane gradients inside the vault, the absence of soot and possible ignition sources, the analysis did not yield a well-defined, credible gas explosion scenario to explain the observed damage, although the possibility cannot be ruled out with absolute certainty. (C) 2018 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.

Abstract:
We investigate whether an increase in the potential earnings of men leads to an increase in marriage and a reduction in nonmarital births by exploiting the positive economic shock associated with fracking in the 2000s. A reduced-form analysis reveals that in response to local-area fracking production, which increased wages and jobs for non-college-educated men, both marital and nonmarital birth rates increase, but marriage rates do not. The pattern of results is consistent with positive income effects on births but no associated increase in marriage. We contrast our findings to the Appalachian coal boom experience of the 1970s and 1980s.

Abstract:
Aotearoa New Zealand is a little-known oil and gas producer with a long history of conventional, small-volume extraction in the province of Taranaki. The development of unconventional technologies coupled with political and economic interest in expanding extraction positioned communities and landscapes with no previous history into becoming emergent, extractive frontiers. Data from interviews, observations, and publicly available documents were collected and analyzed to study how fracking vulnerable communities responded to oil and gas proposals for exploration. This study found that residents of the first-fracked communities of Taranaki became national experts, informants, and translators for the fracking vulnerable regions. This study also found that first-fracked communities in English-speaking nations served, whether knowingly or not, as an additional well of publicly accessible insight whether they experienced earthquakes in Oklahoma, mobilized resistance in England, or locked their gates in Australia. This global exchange revealed a globalization of citizen knowledge for vulnerable communities to challenge becoming the next frontier. Finally, this study found that a civic boomerang occurred, in which residents of the frontiers who were opposed to hydraulic fracturing discovered the problems of extraction and turned a more critical lens on the industry’s workaday practices in the province of Taranaki.

Abstract:
In the U.S., the current regulatory regime for unconventional oil and gas development is extremely contested, with controversial exemptions buried in federal law and significant state-local conflict. Hence, the question of the appropriate scale of governance (e.g. federal, state, or local) for oil and gas development is unsettled. In this analysis, we consider the views of local policy actors in the western states of Utah and Colorado. We ask how factors such as the perceived importance of the industry and local economic conditions influence scalar preferences. Results imply that local policy actors tend to endorse local control and are generally not supportive of federal exemptions.

Abstract:
BACKGROUND: Hydraulically fractured wells produce 2–14 million liters of wastewater, which may contain toxic and radioactive compounds. The wastewater is predominantly disposed of using Class II injection wells. OBJECTIVE: Our objective was to evaluate the relationship between sociodemographic characteristics and injection well locations in Ohio. METHODS: Using state and federal data sources, we classified Ohio census block groups by presence of injection wells, number of hydraulically fractured wells, sociodemographic factors (median household income, % white, population density, % ≥high school education, median age, voter turnout), and geographic information (land area, water area, situated over shale). We modeled the odds of having at least one injection well within a block group with respect to all covariates using three multivariable models incorporating different spatial components to account for similarities in neighboring block groups. RESULTS: In bivariate analyses, block groups with injection wells (n=156) compared with those without (n=9,049) had lower population density (71 vs. 2,210 people/mi2 or 27 vs. 854 people/km2), larger median area (43.5 vs. 1.35 km2), higher median age (42.8 vs. 40.2 y), and higher % white (98.1% vs. 92.1%). After adjustment using a spatial logistic regression model, the odds of a block group containing an injection well were 16% lower per $10,000 increase in median income [odds ratio(OR)=0.837; 95% credible interval (CI): 0.719, 0.961] and 97% lower per 1,000 people/mi2 (or per 386 people/km2) increase (OR=0.030; 95% CI=0.008, 0.072). Block groups on shale and those containing fewer hydraulically fractured wells were more likely to include an injection well. Percentage white, median age, % ≥high school education, and % voter turnout were not significant predictors of injection well presence. CONCLUSION: In Ohio, injection wells were inversely associated with block groups’ median incomes after adjusting for other sociodemographic and geographic variables. Research is needed to determine whether residents in census blocks with injection wells face increased risk of chemical exposures or adverse health outcomes.

Abstract:
The boom in shale gas production has been accompanied by concerns that polycentricity, whereby multiple levels of government share regulatory authority, has resulted in an inefficient and ineffective governance. The Bloomington School of institutional analysis suggests otherwise. Drawing on the work of Elinor and Vincent Ostrom, we clarify a diverse regulatory response to shale gas development within federations may be appropriate depending on the physical context of shale gas development, local demand for economic development (including geology, geography, and the built environment), the regulatory capacity of local governments, uncertainty about the appropriate regulations to address externalities from shale gas production, and the extent of inter-jurisdictional coordination problems. We apply the framework to regulation of shale gas development two fracking federations: the US and EU. In each context, letting a thousand regulatory flowers bloom is more sensible than uniform standards.

Abstract:
Hydraulic fracturing has provided a persistent, polarizing, and highly politicized source of controversy internationally, and in numerous national contexts for just under a decade. This research uses fracking operations in New Zealand as a vignette through which to understand the underlying causes of controversy and the appropriateness of attempts to address them. A multi-method approach using interviews (n=25), diagrammatic analysis, and newsprint media was applied to evidence two major findings. Firstly, previous attempts to explain fracking controversy based on social constructivist theory lack a multi-scalar approach to the assessment of factors that influence risk perceptions. It is found that risk perception surrounding fracking in New Zealand reflects intra-scalar interactions between factors originating at the international, national, regional and local scale. Secondly, there is a concerning absence of critique pertaining to the concept of ‘social license to operate’ (SLO), which has been advocated both internationally and nationally as an appropriate form of stakeholder engagement. This paper contributes to the SLO outcomes literature by establishing a need to consider multi-scalar influences on risk perception when explaining diverse SLO outcomes in communities where fracking operations are prospective or already taking place.

Abstract:
Hydraulic fracturing, or fracking, is a technique used to excavate natural gas and oil trapped within porous layers of shale thousands of feet below the surface. The process stands to provide enormous benefits to the United States as a means of harvesting a previously unobtainable source of energy and of alleviating dependence on foreign oil. There are clear challenges which must be overcome, however, to fairly address public concerns over the amount of toxic chemicals used and the potential dangers posed to drinking water resources. Written from an engineering standpoint, this report aims to identify the challenges that the industry is facing while posing reasonable solutions. The body of the report examines established literature on the technology utilized by fracking, its impacts on the environment and human health, the current state of government regulations on fracking, its impact on the U.S. economy, and its required infrastructure, among other topics of interest. With improving technology, many fracking problems are already being addressed. A challenge, however, is for industry to begin taking some appropriate, more preventative actions. Certain regulations have been enacted, yet opportunities still exist where industry can implement break-through concepts and abandon outdated and harmful technologies. Serious problems which must be addressed are the insufficient monitoring of the life of injected chemicals and the lack of options for handling produced wastewater. It would thus be of great value to equip public facilities with the ability to treat the complex waste water produced from hydrofracking, as many waste-water treatment plants in the country are not currently capable of this. Additionally, an overhaul of current regulations to increase their transparency and overall effectiveness would significantly minimize the hazardous footprint of the industry and improve its outlook for the future.

Abstract:
Methane emissions from the U.S. oil and natural gas supply chain were estimated using ground-based, facility-scale measurements and validated with aircraft observations in areas accounting for ~30% of U.S. gas production. When scaled up nationally, our facility-based estimate of 2015 supply chain emissions is 13 ± 2 Tg/y, equivalent to 2.3% of gross U.S. gas production. This value is ~60% higher than the U.S. EPA inventory estimate, likely because existing inventory methods miss emissions released during abnormal operating conditions. Methane emissions of this magnitude, per unit of natural gas consumed, produce radiative forcing over a 20-year time horizon comparable to the CO2 from natural gas combustion. Significant emission reductions are feasible through rapid detection of the root causes of high emissions and deployment of less failure-prone systems.

Abstract:
A fuzzy-based indexing approach was developed for the management of hydraulic fracturing chemical additives. The environmental and human health hazards of an additive are converted to hazard indices using an indexing system. To account for uncertainties, a fuzzy-based approach is adopted based on fuzzy inference and fuzzy clustering analysis to assess the risk potential of different additives for informed chemical management decision making. The assessment of the randomly selected additives showed that this fuzzy-based indexing approach gave different chemical hazard assessment results for about 30% of the assessed additives. This shows that accounting for uncertainties using this methodology can lead to better informed chemical management decision making. The hazard assessment results also indicate that based on current indexing methodology more than half of the additives permitted for use in hydraulic fracturing operations are considered moderate environmental and human health hazards. However, based on the new fuzzy-based approach the majority (80%) of the additives were identified as low and very low risk potential due to their low use frequencies. (C) 2018 Elsevier Ltd. All rights reserved.

Abstract:
Hydraulic fracturing is one of the industrial processes behind the surging natural gas output in the United States. This technology inadvertently creates an engineered microbial ecosystem thousands of meters below Earth’s surface. Here, we used laboratory reactors to perform manipulations of persisting shale microbial communities that are currently not feasible in field scenarios. Metaproteomic and metabolite findings from the laboratory were then corroborated using regression-based modeling performed on metagenomic and metabolite data from more than 40 produced fluids from five hydraulically fractured shale wells. Collectively, our findings show that Halanaerobium, Geotoga, and Methanohalophilus strain abundances predict a significant fraction of nitrogen and carbon metabolites in the field. Our laboratory findings also exposed cryptic predatory, cooperative, and competitive interactions that impact microorganisms across fractured shales. Scaling these results from the laboratory to the field identified mechanisms underpinning biogeochemical reactions, yielding knowledge that can be harnessed to potentially increase energy yields and inform management practices in hydraulically fractured shales.

Abstract:
Biological treatment is effective but infrequently used for oil and gas produced water. To date, physical–chemical treatment methods have been favored due to the smaller space requirements and operational simplicity. Changing regulatory requirements and increased interest in recycling and beneficial reuse have led to increased interest in biological treatment. To elucidate its potential role, we reviewed and summarized 59 studies on the biological treatment of produced water. Oilfield produced water was predominantly studied (> 50%). More studies using real produced water were from China than from any other country (37%). Real produced water was used in most studies (73%). Studies were predominantly bench-scale experiments (69%). Fixed-film reactors were most prevalent (27%). Water quality of produced waters treated was variable; median total dissolved solids (TDS) was 28,000 mg L−1 and median chemical oxygen demand (COD) was 1125 mg L−1. Inhibition by salinity was variable according to the treatment system and study design, but efficacy generally decreased when TDS was above 50,000 mg L−1. For studies treating real samples, average COD removal was 73% when TDS was less than 50,000 mg L−1, and 54% when TDS was greater than 50,000 mg L−1. Key issues were microbial acclimation, toxicity, biological fouling, and mineral scaling. Finding an inoculum was not problematic as microorganisms capable of degrading hydrocarbons were isolated from various environments. Treatment performance was better where synthetic produced water was used in lieu of real samples. Biological treatment is promising for producing effluents suitable for reuse, particularly where it functions as part of a larger treatment train.

Abstract:
Eleven thousand groundwater samples collected in the 2010s in an area of Marcellus shale-gas development are analyzed to assess spatial and temporal patterns of water quality. Using a new data mining technique, we confirm previous observations that methane concentrations in groundwater tend to be naturally elevated in valleys and near faults, but we also show that methane is also more concentrated near an anticline. Data mining also highlights waters with elevated methane that are not otherwise explained by geologic features. These slightly elevated concentrations occur near 7 out of the 1,385 shale-gas wells and near some conventional gas wells in the study area. For ten analytes for which uncensored data are abundant in this 3,000 km2 rural region, concentrations are unchanged or improved as compared to samples analyzed prior to 1990. Specifically, TDS, Fe, Mn, sulfate, and pH show small but statistically significant improvement, and As, Pb, Ba, Cl, and Na show no change. Evidence from this rural area could document improved groundwater quality caused by decreased acid rain (pH, sulfate) since the imposition of the Clean Air Act or decreased steel production (Fe, Mn). Such improvements have not been reported in groundwater in more developed areas of the U.S.

Abstract:
Environmental issues have become some of the greatest challenges encountered across the life cycle Shale gas operations, and mostly involve the management, disposal, and spill of flowback and produced (FP) waters during the process of hydraulic fracturing. This study evaluates Shale gas resources, addresses water resource management problems, and identifies the corresponding environmental implications of FP waters under uncertainty. Multiple tools, including structural optimization, process design, cost analysis, environmental assessment, and stochastic technology, are integrated into a general modeling framework based on game theory. This mathematic framework corresponds to a dominant-subordinate-interactive problem, where two major participants are identified as the downstream decision maker at the dominant level (e.g., power generation sector) and the upstream decision maker at the subordinate level (e.g., Shale gas producer). The Monte Carlo technique is used for simulating the estimated ultimate recovery (EUR) of a single well. Thereafter, the developed model is applied to a special case study of the Marcellus Shale play in Beaver County, Pennsylvania. Multiple decisions regarding gas production, processing, water management, as well as electricity generation would been examined under different probability levels. Results indicate that the changes in violation levels would lead to distinct environmental and economic performances of the supply chain. A lower probability level of the EUR value would correspond to an increased reliability on fulfilling the system demands, and then to higher economic benefits and freshwater supply; conversely, a higher probability level of the EUR value would result in lower economic benefits and lower freshwater supply, and the risk of violating the EUR value would also increase.

Abstract:
Concern persists over the potential for unconventional oil and gas development to contaminate groundwater with methane and other chemicals. These concerns motivated our 2-year prospective study of groundwater quality within the Marcellus Shale. We installed eight multilevel monitoring wells within bedrock aquifers of a 25-km2 area targeted for shale gas development (SGD). Twenty-four isolated intervals within these wells were sampled monthly over 2 years and groundwater pressures were recorded before, during, and after seven shale gas wells were drilled, hydraulically fractured, and placed into production. Perturbations in groundwater pressures were detected at hilltop monitoring wells during drilling of nearby gas wells and during a gas well casing breach. In both instances, pressure changes were ephemeral (<24 hours) and no lasting impact on groundwater quality was observed. Overall, methane concentrations ([CH4]) ranged from detection limit to 70 mg/L, increased with aquifer depth, and, at several sites, exhibited considerable temporal variability. Methane concentrations in valley monitoring wells located above gas well laterals increased in conjunction with SGD, but CH4 isotopic composition and hydrocarbon composition (CH4/C2H6) are inconsistent with Marcellus origins for this gas. Further, salinity increased concurrently with [CH4], which rules out contamination by gas phase migration of fugitive methane from structurally compromised gas wells. Collectively, our observations suggest that SGD was an unlikely source of methane in our valley wells, and that naturally occurring methane in valley settings, where regional flow systems interact with local flow systems, is more variable in concentration and composition both temporally and spatially than previously understood.

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Here, we report the first results of model sensitivity simulations to assess the potential impacts of emissions related to future activities linked to unconventional hydrocarbon extraction (fracking) in the UK on air pollution and human health. These simulations were performed with the Met Office Air Quality in the Unified Model, a new air quality-forecasting model, and included a wide range of extra emissions of volatile organic compounds (VOCs) and nitrogen oxides (NOx) to reflect emissions from the full life cycle of fracking-related activities and simulate the impacts of these compounds on levels of nitrogen dioxide (NO2) and ozone (O3). These model simulations highlight that increases in NOx and VOC emissions associated with unconventional hydrocarbon extraction could lead to large local increases in the monthly means of daily 1-h maximum NO2 of up to + 30 ppb and decreases in the maximum daily 8-h mean O3 up to − 6 ppb in the summertime. Broadly speaking, our simulations indicate increases in both of these compounds across the UK air shed throughout the year. Changes in the 1-h maximum of NO2 and 8-h mean of O3 are particularly important for their human health impacts. These respective changes in NO2 and O3 would contribute to approximately 110 (range 50–530) extra premature-deaths a year across the UK based on the use of recently reported concentration response functions for changes in annual average NO2 and O3 exposure. As such, we conclude that the release of emissions of VOCs and NOx be highly controlled to prevent deleterious health impacts.

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France has a long history in mining and, to a lesser extent, in hydrocarbon extraction, but these industries were both in decline by the end of the 20th century. Following the American shale boom in the 2000′s, there was a sudden renewal of hydrocarbon exploration in 2010 with new exploration licenses being delivered for unconventional oil and gas projects. These projects first remained confined to specialists of such industries until the end of 2010, when a massive social movement opposed shale gas exploration. This paper aims at drawing a picture of this social movement and its narrative work to obtain the ban on hydraulic fracturing by the French government in 2011. Showing the oil and gas supporters’ failed attempts to reopen the debate in the following years, we outline how the ban contributed to negatively shape the representation of extractive industries outside unconventional hydrocarbons. We demonstrate that i) public and political perceptions of unconventional gas in general were built mostly during the sudden burst of mobilization in late 2010, with the opponent’s narratives encountering almost no resistance, ii) previous knowledge and experience with extractive industries in some areas of France facilitates social license for unconventional gas without the use of hydraulic fracturing there, but it does not guarantee the development of the industry, iii) the controversy about hydraulic fracturing participated to shape negative perception about extractive industries in France in general, including ore mining.

Abstract:

The scale of harm to health is uncertain, but the danger of exacerbating climate change is not

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Shale oil and gas exploitation by hydraulic fracturing experienced a strong development worldwide over the last years, accompanied by a substantial increase of related induced seismicity, either consequence of fracturing or wastewater injection. In Europe, unconventional hydrocarbon resources remain underdeveloped and their exploitation controversial. In UK, fracturing operations were stopped after the Mw 2.3 Blackpool induced earthquake; in Poland, operations were halted in 2017 due to adverse oil market conditions. One of the last operated well at Wysin, Poland, was monitored independently in the framework of the EU project SHEER, through a multidisciplinary system including seismic, water and air quality monitoring. The hybrid seismic network combines surface mini-arrays, broadband and shallow borehole sensors. This paper summarizes the outcomes of the seismological analysis of these data. Shallow artificial seismic noise sources were detected and located at the wellhead active during the fracturing stages. Local microseismicity was also detected, located and characterised, culminating in two events of Mw 1.0 and 0.5, occurring days after the stimulation in the vicinity of the operational well, but at very shallow depths. A sharp methane peak was detected ~19 hours after the Mw 0.5 event. No correlation was observed between injected volumes, seismicity and groundwater parameters.

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The chemistry of hydraulic fracturing fluids and wastewaters is complex and is known to vary by operator, geologic formation, and fluid age. A time series of hydraulic fracturing fluids, flowback fluids, and produced waters was collected from two adjacent Marcellus Shale gas wells for organic chemical composition analyses using ultrahigh resolution mass spectrometry. Hierarchical clustering was used to compare and extract ions related to different fluid ages and many halogenated organic molecular ions were identified in flowback fluids and early produced waters based on exact mass. Iodinated organic compounds were the dominant halogen class in these clusters and were nearly undetectable in hydraulic fracturing fluid prior to injection. The iodinated ions increased in flowback and remained elevated after ten months of well production. We suggest that these trends are mainly driven by dissolved organic matter reacting with reactive halogen species formed abiotically through oxidizing chemical additives applied to the well and biotically via iodide-oxidizing bacteria. Understanding the implications of these identified halogenated organic compounds will require future investigation in to their structures and environmental fate.

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Horizontal drilling and hydraulic fracturing are technologies designed to increase natural gas flow and to improve productivity in low permeability formations. During this drilling operation, tons of flowback and produced water, which contain several organic compounds, return to the surface with a potential risk of influencing the surrounding environment and human health. In order to conduct predictive risk assessments a mathematical model is needed to evaluate organic compound behaviour along the water transportation process as well as concentration changes over time throughout the operational life cycle. A comprehensive model, which fits the experimental data, combining an Organic Matter Transport Dynamic Model with a Two-Compartment First-order Rate Constant (MC) Model has been established to quantify the organic compounds concentrations. This algorithm model incorporates two transportation rates, fast and slow. The results show that the higher the value of the organic carbon partition coefficient (k(oc)) in chemicals, the later the maximum concentration in water will be reached. The maximum concentration percentage would reach up to 90% of the available concentration of each compound in shale formation (whose origin may be associated to drilling fluid, connate water and/or rock matrix) over a sufficiently long period of time. This model could serve as a contribution to enhance monitoring strategy, increase benefits out of optimizing health risk assessment for local residents and provide initial baseline data to further operations. (C) 2018 Elsevier B.V. All rights reserved.

Abstract:
Degradation of groundwater quality is a primary public concern in rural hydraulic fracturing areas. Previous studies have shown that natural gas methane (CH4) is present in groundwater near shale gas wells in the Marcellus Shale of Pennsylvania, but did not have pre-drilling baseline measurements. Here, we present the results of a free public water testing program in the Utica Shale of Ohio, where we measured CH4 concentration, CH4 stable isotopic composition, and pH and conductivity along temporal and spatial gradients of hydraulic fracturing activity. Dissolved CH4 ranged from 0.2 μg/L to 25 mg/L, and stable isotopic measurements indicated a predominantly biogenic carbonate reduction CH4 source. Radiocarbon dating of CH4 in combination with stable isotopic analysis of CH4 in three samples indicated that fossil C substrates are the source of CH4 in groundwater, with one 14C date indicative of modern biogenic carbonate reduction. We found no relationship between CH4 concentration or source in groundwater and proximity to active gas well sites. No significant changes in CH4 concentration, CH4 isotopic composition, pH, or conductivity in water wells were observed during the study period. These data indicate that high levels of biogenic CH4 can be present in groundwater wells independent of hydraulic fracturing activity and affirm the need for isotopic or other fingerprinting techniques for CH4 source identification. Continued monitoring of private drinking water wells is critical to ensure that groundwater quality is not altered as hydraulic fracturing activity continues in the region. Open image in new window Graphical abstract A shale gas well in rural Appalachian Ohio. Photo credit: Claire Botner.

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Background: Oklahoma has experienced a rise in seismicity since 2010, with many earthquakes induced by wastewater injection. While large single earthquakes have documented mental health repercussions, health implications of these new, frequent earthquakes remain unknown. We aimed to examine associations between Oklahoma earthquakes and statewide anxiety measured by Google queries. Methods: The U.S. Geologic Survey’s Advanced National Seismic System Comprehensive Catalog supplied earthquake dates and magnitudes. We used the Google Health application programming interface to compile the proportion of weekly Oklahoma-based health-related search episodes for anxiety. A quasi-experimental time-series analysis from January 2010 to May 2017 evaluated monthly counts of earthquakes ≥ magnitude 4 (a level felt by most people) in relation to anxiety, controlling for US-wide anxiety search episodes and Oklahoma-specific health-related queries. Results: Oklahoma experienced an average of two (SD = 2) earthquakes ≥ magnitude 4 per month during the study period. For each additional earthquake ≥ magnitude 4, the proportion of Google search episodes for anxiety increased by 1.3% (95% confidence interval = 0.1%, 2.4%); 60% of this increase persisted for the following month. In months with 2 or more ≥ magnitude 4 earthquakes, the proportion of Google search episodes focused on anxiety increased by 5.8% (95% confidence interval = 2.3%, 9.3%). In a sub-analysis, Google search episodes for anxiety peaked about 3 weeks after ≥ magnitude 4 quakes. Conclusions: These findings suggest that the recent increase in Oklahoma earthquakes has elicited a psychological response that may have implications for public health and regulatory policy.

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Multi-stakeholder governance arrangements involving co-operation between public and non-state actors are a vital part of the governance landscape for addressing social impacts resulting from resources development. Yet, the current mantra for ‘collaboration’ has gained relative credibility and legitimacy without scrutiny of the democratic characteristics and quality of these institutional arrangements. This article responds to this normative concern by examining the implications for the democratic legitimacy of multi-stakeholder governance arrangements in cases where private resource extraction companies, who do not necessarily act in the public interest, exercise a ‘metagovernance’ role. We explore this topic through a qualitative case-study comparison of affordable housing governance in regions impacted by unconventional gas development in Australia and the United States. We argue that while multi-stakeholder governance arrangements convened by resource extraction companies can support situations of democracy under certain conditions, resource extraction companies structure the processes within these collaborative arrangements to the benefits of specific actors, notably the extractive companies themselves and other profit-orientated actors. In particular, we illustrate the depoliticizing effects of these institutions, whereby in some cases, they are used to constrain debates about the social impacts of extractives development, and circumscribe certain types of actors from participation in deliberative debate and decision-making. We underscore the importance of state intervention in ensuring communicative processes induced by corporate actors proceed according to the principles of deliberative democracy.

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Increased US oil and gas production has created opportunities and challenges for local governments. Through interviews with roughly 250 local officials, we evaluate the fiscal effects of this development in 21 regions across every major US oil and gas producing state during “boom” and “bust” periods. Growing oil and gas production has increased local government revenues through a variety of mechanisms, including property taxes, sales taxes, severance taxes, and more. Industry activity has also increased costs and demand for local services led by road damage, water and wastewater infrastructure, and a range of staff costs including emergency services and law enforcement. Despite volatility in revenues and service demands, our interview results show that 74% of local governments have experienced net fiscal benefits, 14% reported roughly neutral effects, and 12% reported net fiscal costs. Local governments in highly rural regions experiencing large-scale growth have faced the greatest challenges. To further improve future outcomes, local officials can plan for impacts, state policymakers can re-examine revenue policies, and operators can pursue collaboration with local governments.

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Freshwater shortages in the United States have led to increased use of treated brackish groundwater for domestic, agricultural, and municipal uses. This increased use highlights the need for protecting groundwater resources, especially during unconventional oil and gas development. We analyzed the criteria that define protected groundwater in 17 oil- and natural-gas-producing states. In general, we find that these criteria are ambiguous and do not protect brackish groundwater to criteria established for Underground Sources of Drinking Water (USDWs) in the United States Environmental Protection Agency's Underground Injection Control Program. This lack of consistent protection, and continuing unconventional oil and gas development in formations containing USDWs, highlights the need for all states to protect groundwater to the same federally defined standard for USDWs to safeguard fresh and brackish groundwater for present and future use.

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Permeability enhancing treatments such as hydraulic fracturing (HF) induce microseismic events with typical magnitudes in the -3.0 to -0.5 range, although significantly larger induced earthquakes up to 4.7 in moment magnitude have been reported. Diffusion of pore pressure away from the hydraulic fracture system is thought to be a primary controlling mechanism. Understanding other primary or secondary triggering mechanisms during HF is expected to furnish new insights regarding stress, strength of faults, and rupture initiation and propagation. Using novel methods from statistical seismology, we present evidence for the existence of event-event triggering cascades in microseismicity induced by HF. Although background seismicity dominates, we find that these triggering cascades exhibit features that also characterize tectonic aftershock sequences such as the empirical Omori-Utsu relation and the productivity relation. This suggests that the underlying physical earthquake-earthquake triggering mechanisms are similar in both cases, as also observed for other earthquake swarms. The presence of triggering cascades is of direct relevance for optimizing the effectiveness of the stimulation.

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Thirteen states in the United States allow the spreading of O&G wastewaters on roads for deicing or dust suppression. In this study, the potential environmental and human health impacts of this practice are evaluated. Analyses of O&G wastewaters spread on roads in the northeastern, U.S. show that these wastewaters have salt, radioactivity, and organic contaminant concentrations often many times above drinking water standards. Bioassays also indicated that these wastewaters contain organic micropollutants that affected signaling pathways consistent with xenobiotic metabolism and caused toxicity to aquatic organisms like Daphnia magna. The potential toxicity of these wastewaters is a concern as lab experiments demonstrated that nearly all of the metals from these wastewaters leach from roads after rain events, likely reaching ground and surface water. Release of a known carcinogen (e.g., radium) from roads treated with O&G wastewaters has been largely ignored. In Pennsylvania from 2008 to 2014, spreading O&G wastewater on roads released over 4 times more radium to the environment (320 millicuries) than O&G wastewater treatment facilities and 200 times more radium than spill events. Currently, state-by-state regulations do not require radium analyses prior to treating roads with O&G wastewaters. Methods for reducing the potential impacts of spreading O&G wastewaters on roads are discussed.

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‘Fracking’, or unconventional gas development via hydraulic fracturing (hereafter ‘UGD’), has been closely tied to global climate change in academic discourse. Researchers have debated the life cycle emissions of shale gas versus coal, rates of methane leakage from wellhead production and transmission infrastructure, the extent to which coal would be displaced by gas as a source of energy, the appropriate time-scale for accounting for the global warming potentials of methane and carbon dioxide, surface versus airborne methane measurements, and the effect of lowered energy prices on gas consumption. Little research, however, has examined the degree to which these potential connections between UGD and climate change are relevant to the general public. This article presents two surveys, one of a representative national (US) sample and one of a representative sample of residents in the Marcellus Shale region of Pennsylvania and New York. It examines whether respondents associated UGD with climate change, and the relationship between this association and their support for, or opposition to, UGD. The results reveal that beliefs about many other potential impacts of UGD explain more variation in support and opposition than do beliefs about UGD’s association with climate change. Furthermore, most other impacts of UGD are viewed as having more effect on quality of life if they were to occur, at least amongst the Marcellus Shale survey sample. The article concludes with implications of the findings for policy and communication on UGD.Key policy insights Public opinion about unconventional gas development (UGD or ‘fracking’) is affected less by beliefs about its impact on global climate change, than about several other more local factors.Communication tailored to increase awareness of UGD’s impacts would likely be most effective when focusing on the local level, as opposed to national or global impacts.Messaging about UGD’s relationship with carbon emissions would have more effect in national-level discourse, as opposed to messaging targeted at communities experiencing or potentially experiencing development.To maintain credibility and societal trust, communication on the global climate impacts of UGD needs to be informative but non-persuasive.

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Social equity is an important normative construct in public administration. However, its operationalization is vague and it is empirically underutilized. This article combines political economy, social equity, and environmental justice literatures to explore the contentious issue of hydraulic fracturing for natural gas (commonly called “fracking”). Through interviews with local officials, we show that local officials are aware of equity issues, many take action to reduce inequities related to gas drilling, and equity is often at odds with private property rights. Finally, equity issues are more likely to be associated with inequitable distribution of costs and benefits than traditional distributional social equity.

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Production of natural gas using unconventional technologies has risen as demand for alternative fuels has increased. Impacts on the environment from waste generated from these processes are largely unexplored. In particular, the outcomes of organismal exposure to hydraulic fracturing waste have not been rigorously evaluated. We evaluated the effects of exposure to surrogate hydraulic fracturing waste (HF waste) on mucosal bacterial community structure of the brook trout (Salvelinus fontinalis) epidermis. Brook trout are fish native to streams at risk to HF waste exposure. Here, fish were exposed to four treatments (control, 0.00%; low, 0.01%; medium, 0.10%; and high, 1.0% concentrations) of surrogate HF waste synthesized to mimic concentrations documented in the field. Epidermal mucus samples were collected and assessed 15 days post-exposure to determine if the associated bacterial community varied among treatments. We observed differences in epidermal mucosal bacterial community composition at multiple taxonomic scales among treatments. These community changes reflected compositional differences in taxa dominance and community similarity rather than losses or gains in taxonomic richness. The dominant bacterial genus that explained the greatest variation in community structure between exposed and unexposed fish was Flavobacterium. Two genera associated with salmonid diseases, Flavobacterium and Pseudomonas, were statistically more abundant in high treatments than controls. These results suggest that exposure to low levels of HF waste influences bacterial colonization and may lead to a disruption that favors bacterial populations associated with fish disease.

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This research aimed to elucidate the effect of brine salinity and guar gum on the sorption and transport of Ba in dolomite rocks collected from the Arbuckle formation in Oklahoma, USA. Guar gum represents the most important organic additive used in viscosified fracturing fluids, and Ba constitutes the most common and abundant heavy metal found in unconventional oil and gas (UOG) wastewater. Batch experiments conducted using powdered dolomite rocks (500–600 μm particle size) revealed that at brine salinities of UOG wastewater, chloro-complexation reactions between Ba and Cl ions and pH changes that results from dolomite dissolution are the controlling factors of Ba sorption on dolomite. Competition of Ba with common cations (Ca and Mg) for hydration sites of dolomite, plays a secondary role. Core-flooding experiments conducted to analyze the transport of Ba through natural and synthetic dolomite core plugs are in agreement with the batch sorption experimental results. The transport of Ba through dolomite rocks, increases with increasing brine salinity (0–180,000 mg-NaCl/L). The presence guar gum (50–500 mg/L) does not affect the transport of Ba through dolomite rocks of high flow properties (25–29.6% porosity, 9.6–13.7 mD permeability). However, core-flooding experiments conducted using tight dolomite rocks (6.5–8.6% porosity, 0.06–0.3 mD permeability), revealed that guar gum can retard the transport of Ba by clogging high permeability/porosity regions of tight dolomite rocks. The mechanism of Ba sorption on dolomite can be represented by a sorption model that accounts for both surface complexation reactions on three distinct hydration sites (>CaOHo, >MgOHo, and >CO3Ho), and the kinetic dissolution of dolomite. These results are important in understanding and predicting the fate of Ba present in UOG wastewater disposed into deep dolomite saline aquifers.

Abstract:
The environmental impacts of a typical hydraulic fracturing operation for shale gas recovery were evaluated using life cycle assessment, with energy demands for well drilling and fracturing determined from GHGfrack model. Dominant environmental impacts stem from well construction, which are >63% in all categories (e.g., global warming and eutrophication), and mainly due to diesel fuel combustion and steel production. The relative impacts related to water use (i.e., fracturing fluid components, water/wastewater transportation, and wastewater disposal) are relatively small, ranging from 5 to 22% of total impacts in all categories; freshwater consumption for fracturing is also a small fraction of available water resources for the shale play considered. The impacts of replacing slickwater with CO2 or CH4-foam fracturing fluid (≤10 vol % water) were evaluated; total impacts decrease <12%, and relative impacts related to water use decrease to 2–9% of total impacts. Hence, switching to a foam-based fracturing fluid can substantially decrease water-related impacts (>60%) but has only marginal effects on total environmental impacts. Changes in lateral well length, produced to fresh-water ratios, fracturing fluid composition, and LCA control volume do not change these findings. More benefits could potentially be realized by considering water versus foam-related impacts of ecological health and energy production.

Abstract:
Public concern about oil and gas (O&G) operations in residential areas is substantial. Noise from construction and drilling related to O&G operations may be greater than other phases of O&G operations; yet the impacts of audible and low-frequency noise during these operations are not extensively explored nor the effects on health well understood. This study documents the noise levels at a multi-well O&G well pad during construction and drilling in a residential area in Colorado. A-weighted (dBA) and C-weighted (dBC) noise measurements were collected at four locations during development over a 3-month period. The maximum 1-min equivalent continuous sound levels over a 1-month period were 60.2 dBA and 80.0 dBC. Overall, 41.1% of daytime and 23.6% of nighttime dBA 1-min equivalent continuous noise measurements were found to exceed 50 dBA, and 97.5% of daytime and 98.3% of nighttime measurements were found to exceed 60 dBC. Noise levels exceeding 50 dBA or 60 dBC may cause annoyance and be detrimental to health; thus, these noise levels have the potential to impact health and noise levels and associated health effects warrant further investigation.