Repository for Oil and Gas Energy Research (ROGER)

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Biocides used in unconventional oil and gas (UOG) practices, such as hydraulic fracturing, control microbial growth. Unwanted microbial growth can cause gas souring, pipeline clogging, and microbial-induced corrosion of equipment and transportation pipes. However, optimizing biocide use has not been a priority. Moreover, biocide efficacy has been questioned because microbial surveys show an active microbial community in hydraulic fracturing produced and flowback water. Hydraulic fracturing produced and flowback water increases risks to surface aquifers and rivers/lakes near the UOG operations compared with conventional oil and gas operations. While some biocides and biocide degradation products have been highlighted as chemicals of concern because of their toxicity to humans and the environment, the selective antimicrobial pressure they cause has not been considered seriously. This perspective article aims to promote research to determine if antimicrobial pressure in these systems is cause for concern. UOG practices could potentially create antimicrobial resistance hotspots under-appreciated in the literature, practice, and regulation arena, hotspots that should not be ignored. The article is distinctive in discussing antimicrobial resistance risks associated with UOG biocides from a biological risk, not a chemical toxicology, perspective. We outline potential risks and highlight important knowledge gaps that need to be addressed to properly incorporate antimicrobial resistance emergence and selection into UOG environmental and health risk assessments.

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Publicly available chemical assessments of hydraulic fracturing related waters are generally based on shale gas practices in the U.S. There is a lack of information on hydraulic fracturing related gas development from EU countries and more generally on other types of extractions. This research fills this knowledge gap by presenting chemical and bioassay assessments of hydraulic fracturing related waters from a tight gas development in the Netherlands. Fracturing fluid, flowback water and groundwater from surrounding aquifers before and after the actual fracturing were analysed by means of high resolution liquid chromatography tandem mass spectrometry, the Ames test and three chemical activated luciferase gene expression bioassays aimed at determining genotoxicity, oxidative stress response and polyaromatic hydrocarbon contamination. After sample enrichment a higher number of peaks can be found in both fracturing fluid and flowback samples. No clear differences in chemical composition were shown in the groundwater samples before and after hydraulic fracturing. Preliminary environmental fate data of the tentatively identified chemicals points towards persistence in water. Clear genotoxic and oxidative stress responses were found in the fracturing fluid and flowback samples. A preliminary suspect screening resulted in 25 and 36 matches in positive and negative ionisation respectively with the 338 possible suspect candidates on the list. Extensive measures relating to the handling, transport and treatment of hydraulic fracturing related waters are currently in place within the Dutch context. The results of the present study provide a scientific justification for such measures taken to avoid adverse environmental and human health impacts.

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According to the United States Environmental Protection Agency (U.S. EPA), exposure to radon gas is the second leading cause of lung cancer after smoking. Extant research that has reported that fracking activity increases the radon levels. ‘Fracking’ also known as hydraulic fracturing, which is a technology that is used to extract naturally occurring shale gas from the Marcellus and the Utica shale. Based on the data from the Ohio Radon Information System (ORIS) from 2007-2014 in Ohio, this research uses multilevel modeling (MLM) to examine the association between the incidences of hydraulic fracturing and elevated airborne radon levels. The ORIS data include information on 118,421 individual records of households geocoded to zip code areas. Individual records include radon concentrations, device types of the test, and seasons. Euclidean distances between zip code centroid to the 1,162 fracking wells are measured at the zip code level. Two additional zip code variables, namely the population density and urbanicity, are also included as control variables. Multilevel modeling results show that at the zip code level, distance to fracking wells and population density are significant and negative covariate of the radon concentration; and by comparing with urban areas, urban clusters and rural areas are significant which linked to higher radon concentrations. These findings lend support to the effect of hydraulic fracturing in influencing radon concentrations, and promote public policies that need to be geographically adaptable.

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Previous studies conducted in our laboratory have found altered adult health outcomes in animals with prenatal exposure to environmentally relevant levels of unconventional oil and gas (UOG) chemicals with endocrine-disrupting activity. This study aimed to examine potential metabolic health outcomes following a preconception, prenatal and postnatal exposure to a mixture of 23 UOG chemicals. Prior to mating and from gestation day 1 to postnatal day 21, C57BL/6J mice were developmentally exposed to a laboratory-created mixture of 23 UOG chemicals in maternal drinking water. Body composition, spontaneous activity, energy expenditure, and glucose tolerance were evaluated in 7-month-old female offspring. Neither body weight nor body composition differed in 7-month female mice. However, females exposed to 1.5 and 150 µg/kg/day UOG mix had lower total and resting energy expenditure within the dark cycle. In the light cycle, the 1500 µg//kg/day group had lower total energy expenditure and the 1.5 µg/kg/day group had lower resting energy expenditure. Females exposed to the 150 µg/kg/day group had lower spontaneous activity in the dark cycle, and females exposed to the 1500 µg/kg/day group had lower activity in the light cycle. This study reports for the first time that developmental exposure to a mixture of 23 UOG chemicals alters energy expenditure and spontaneous activity in adult female mice.

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This study presents observations using new data from a deployment of eight broadband seismometers surrounding a horizontal well pad at distances of 1-3 km for the period before, during, and after a hydraulic fracturing (HF) treatment in the Montney Basin, British Columbia, Canada. We use a multi-station matched filter detection and double-difference earthquake relocation to develop a catalog of 350 events associated with HF stimulation, with magnitudes ranging from -2.8 to 1.8 and estimated catalog completeness of -0.2. The seismicity distribution suggests a statistically significant association with injection, and event migration can be described by a hydraulic diffusivity of 0.2 m2/s. A comparison between daily seismicity rate and analytical stress evolution inferred from daily injection volumes implies that pore pressure diffusion largely controls earthquake nucleation at distances less than 1 km, whereas poroelastic stress transfer likely dominates at intermediate distances of 1-4 km at time scales shorter than diffusion. Both mechanisms likely have a limited effect on stress perturbation at distances over 5 km.

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Increased energy demands and innovations in upstream oil and natural gas (ONG) extraction technologies have enabled the United States to become one of the world's leading producers of petroleum and natural gas hydrocarbons. The US Environmental Protection Agency (EPA) lists 187 hazardous air pollutants (HAPs) that are known or suspected to cause cancer or other serious health effects. Several of these HAPs have been measured at elevated concentrations around ONG sites, but most have not been studied in the context of upstream development. In this review, we analyzed recent global peer-reviewed articles that investigated HAPs near ONG operations to (a) identify HAPs associated with upstream ONG development, (b) identify their specific sources in upstream processes, and (c) examine the potential for adverse health outcomes from HAPs emitted during these phases of hydrocarbon development.

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According to the United States Environmental Protection Agency (U.S. EPA), exposure to radon gas is the second leading cause of lung cancer after smoking. Extant research that has reported that fracking activity increases the radon levels. ‘Fracking’ also known as hydraulic fracturing, which is a technology that is used to extract naturally occurring shale gas from the Marcellus and the Utica shale. Based on the data from the Ohio Radon Information System (ORIS) from 2007-2014 in Ohio, this research uses multilevel modeling (MLM) to examine the association between the incidences of hydraulic fracturing and elevated airborne radon levels. The ORIS data include information on 118,421 individual records of households geocoded to zip code areas. Individual records include radon concentrations, device types of the test, and seasons. Euclidean distances between zip code centroid to the 1,162 fracking wells are measured at the zip code level. Two additional zip code variables, namely the population density and urbanicity, are also included as control variables. Multilevel modeling results show that at the zip code level, distance to fracking wells and population density are significant and negative covariate of the radon concentration; and by comparing with urban areas, urban clusters and rural areas are significant which linked to higher radon concentrations. These findings lend support to the effect of hydraulic fracturing in influencing radon concentrations, and promote public policies that need to be geographically adaptable.

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Hydraulic fracturing is a prominent method of natural gas production that uses injected, high-pressure fluids to fracture low permeability, hydrocarbon rich strata such as shale. Upon completion of a well, the fluid returns to the surface (produced water) and contains natural gas, subsurface constituents, and microorganisms (Barbot et al., 2013, Daley et al., 2016). While the microbial community of the produced fluids has been studied in multiple gas wells, the activity of these microorganisms and their relation to biogeochemical activity is not well understood. In this experiment, we supplemented produced fluid with 13C-labeled carbon sources (glucose, acetate, bicarbonate, methanol, or methane), and 15N-labeled ammonium chloride in order to isotopically trace microbial activity over multiple day in anoxic incubations. Nanoscale secondary ion mass spectrometry (NanoSIMS) was used to generate isotopic images of 13C and 15N incorporation in individual cells, while isotope ratio monitoring – gas chromatography – mass spectrometry (IRM-GC-MS) was used to measure 13CO2, and 13CH4 as metabolic byproducts. Glucose, acetate, and methanol were all assimilated by microorganisms under anoxic conditions. 13CO2 production was only observed with glucose as a substrate indicating that catabolic activity was limited to this condition. The microbial communities observed at 0, 19, and 32 days of incubation did not vary between different carbon sources, were low in diversity, and composed primarily of the class Clostridia. The primary genera detected in the incubations, Halanaerobium and Fusibacter, are known to be adapted to harsh physical and chemical conditions consistent with those that occur in the hydrofracturing environment. This study provides evidence that microorganisms in produced fluid are revivable in laboratory incubations and retained the ability to metabolize added carbon and nitrogen substrates.

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High-volume, hydraulic fracturing (HVHF) is widely applied for natural gas and oil production from shales, coals or tight sandstone formations in the United States, Canada, and Australia, and is being widely considered by other countries with similar unconventional energy resources. Secure retention of fluids (natural gas, saline formation waters, oil, HVHF fluids) during and after well stimulation is important to prevent unintended environmental contamination, and release of greenhouse gases to the atmosphere. Here, we critically review state-of-the-art techniques and promising new approaches for identifying oil and gas production from unconventional reservoirs to resolve whether they are the source of fugitive methane and associated contaminants into shallow aquifers. We highlight future research needs and propose a phased program, from generic baseline to highly specific analyses, to inform HVHF and unconventional oil and gas production and impact assessment studies. These approaches may also be applied to broader subsurface exploration and development issues (e.g., groundwater resources), or new frontiers of low-carbon energy alternatives (e.g., subsurface H2 storage, nuclear waste isolation, geologic CO2 sequestration).

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Hydraulic fracturing in shale/tight gas reservoirs creates fracture network systems that can intersect pre-existing subsurface flow pathways, e.g. fractures, faults or abandoned wells. This way, hydraulic fracturing operations could possibly pose environmental risks to shallow groundwater systems. This paper explores the long-term (>30 years) flow and transport of fracturing fluids into overburden layers and groundwater aquifers through a leaky abandoned well, using the geological setting of North German Basin as a case study. A three-dimensional model consisting of 15 sedimentary layers with three hydrostratigraphic units representing the hydrocarbon reservoir, overburden, and the aquifer is built. The model considers one perforation location at the first section of the horizontal part of the well, and a discrete hydraulic fracture intersecting an abandoned well. A sensitivity analysis is carried out to quantify and understand the influence of a broad spectrum of field possibilities (reservoir properties, overburden properties, salinity, abandoned well properties and its proximity to hydraulic fractures) on the flow of fracturing fluid to shallower permeable strata. The model results suggest the spatial properties of the abandoned well as well as its distance from the hydraulic fracture are the most important factors influencing the vertical flow of fracturing fluid. It is observed that even for various field settings, only a limited amount fracturing fluid can reach the aquifer in a long-term period.

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The U.S. is undergoing a rapid energy transition, driven in large part an explosion in oil and gas production driven by unconventional drilling technologies. Some communities have embraced the boom in new oil and gas production, often resisting efforts to regulate the oil and gas industry. On the other hand, some states and municipalities have effectively banned new oil and gas drilling. In this paper, we examine how natural resource dependence, local economic conditions, and perceived economic benefits relate to support for restrictive oil and gas regulations in Colorado, US. Using representative survey data, our results suggest that perceived benefits, especially in the form of tax revenue, predict oil and gas policy preferences, while local and personal economic circumstances have little impact.

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Natural gas (NG) from shale formations (or shale gas) is an unconventional energy resource whose potential environmental impacts are still not adequately assessed. Hence, this study performs a Life Cycle Assessment (LCA) of shale gas considering a gas well under appraisal in Burgos, Spain. An attributional model was developed, considering the NG pre-production and production phases in the system boundaries, considering 1 MJ of processed NG as a functional unit. Results were obtained through the CML-IA baseline method (developed by the Center of Environmental Science of Leiden University) and showed that well design, drilling and casing, hydraulic fracturing, NG production, gathering, and processing are critical processes. To better address the environmental impacts, a comparison with similar studies was carried out, as well as a sensitivity and an uncertainty analysis using Monte Carlo simulation (MCS). The model was found to be particularly sensitive to water usage in hydraulic fracturing and to the number of workovers with hydraulic fracturing. Limited data availability for shale gas exploration still poses a challenge for an accurate LCA. Even though shale gas remains controversial, it still can be considered as a strategic energy resource, requiring a precautionary approach when considering its exploitation and exploration.

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Hydraulic fracturing wastewaters (HFWWs) contain synthetic organic components and metal ions derived from the formation waters. The risk of spills of HFWW that could impact soil quality and water resources is of great concern. The ability of synthetic components, such as surfactants, in HFWW to be transported through soil and to mobilize metals in soil was examined using column experiments. A spill of HFWW was simulated in bench scale soil column experiments that used an agricultural soil and simulated seven 10-year rain events representing a total of one year's worth of precipitation for Weld County, Colorado. Although no surfactants or their transformation products were found in leachate samples, copper, lead, and iron were mobilized at environmentally relevant concentrations. In general, after the initial spill event, metal concentrations increased until the fourth rain event before decreasing. Results from this study suggest that transport of metals was caused by the high concentrations of salts present in HFWW. This is the first study utilizing authentic HFWWs to investigate the transport of surfactants and their effect on metal mobilization. Importantly, a significant decrease in the water infiltration rate of the soil was observed, leading to the point where water was unable to percolate through due to increasing salinity, potentially having a severe impact on crop production.

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Background Natural gas drilling may pose multiple health risks, including congenital anomalies, through air pollutant emissions and contaminated water. Two recent studies have evaluated the relationship between natural gas activity and congenital anomalies, with both observing a positive relationship. Objectives We aimed to evaluate whether residence near natural gas wells is associated with critical congenital heart defects (CCHD), neural tube defects (NTD), and oral clefts in Oklahoma, the third highest natural gas producing state in the US. Methods We conducted a retrospective cohort study among singleton births in Oklahoma (n = 476,600) to evaluate natural gas activity and congenital anomalies. We calculated an inverse distance-squared weighted (IDW) score based on the number of actively producing wells within a two-mile radius of the maternal residence during the month of delivery. We used modified Poisson regression with robust error variance to estimate prevalence proportion ratios (PPR) and 95% confidence intervals (CI) for the association between tertiles of natural gas activity (compared to no wells) and CCHD, NTD, and oral clefts adjusted for maternal education. Results We observed an increased, though imprecise, prevalence of NTDs among children with natural gas activity compared to children with no wells (2nd tertile PPR: 1.34, 95% CI: 0.93, 1.93; 3rd tertile PPR: 1.20, 95% CI: 0.82, 1.75). We observed no association with CCHD or oral clefts overall. Specific CCHDs of common truncus, transposition of the great arteries, pulmonary valve atresia and stenosis, tricuspid valve atresia and stenosis, interrupted aortic arch, and total anomalous pulmonary venous connection were increased among those living in areas with natural gas activity compared to those living in areas without activity, though not statistically significant. Discussion Our results were similar to previous studies for NTDs and specific CCHDs. Future directions include evaluating the association between specific phases of the drilling process and congenital anomalies to better refine the relevant exposure period.

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In PNAS, Woda et al. (1) present the results of a multidimensional investigation of the impacts of several hydraulically fractured shale gas wells on an aquifer and a hydrologically connected stream in a particular area in central Pennsylvania. The stream, Sugar Run, has been impacted by migration of methane into it. Sugar Run has inflow of groundwater from aquifers overlying the Marcellus Shale, which is relatively close to the land surface in the study area (e.g., one shale gas well of primary focus in the study is reported to intersect the Marcellus Shale at a depth of 997 m). Stream samples and groundwater samples were collected upstream and downstream from a location in Sugar Run where intermittent bubbling and groundwater seepage have been observed for at least 4 y since intensive shale gas development began in the study area in 2008. Samples were analyzed for dissolved methane; Na, Ca, Mg, Fe, Mn, SO42−, Cl−, and other inorganic solutes; carbon and strontium isotopes; and noble gases. The authors also obtained and analyzed regional groundwater-quality data and water-quality data for Sugar Run before shale gas development. Analysis of the water-quality data with consideration of regional characteristics and surface and groundwater characteristics before shale gas development led Woda et al. (1) to conclude from multiple lines of evidence that Sugar Run and the aquifer(s) that provide inflow to the stream have been contaminated by “new methane” mobilized by the shale gas development. They propose a water-quality indicator of the presence of recent methane contamination, namely, high sulfate (>6 mg/L) and iron (>0.3 mg/L) in waters with high methane concentrations. The protocol developed by the authors for use of aqueous geochemical conditions to identify impacts associated with new methane will be useful in the Marcellus region and, perhaps, in … [↵][1]1Email: dzombak{at}cmu.edu. [1]: #xref-corresp-1-1

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Hydraulic fracturing flowback and produced water (FPW) samples were analyzed for toxicity and microbiome characterization over 220 days for a horizontally drilled well in the Denver-Julesberg (DJ) Basin in Colorado. Cytotoxicity, mutagenicity, and estrogenicity of FPW were measured via the BioLuminescence Inhibition Assay (BLIA), Ames II mutagenicity assay (AMES), and Yeast Estrogen Screen (YES). Raw FPW stimulated bacteria in BLIA, but were cytotoxic to yeast in YES. Filtered FPW stimulated cell growth in both BLIA and YES. Concentrating 25× by solid phase extraction (SPE) revealed significant toxicity throughout well production by BLIA, toxicity during the first 55 days of flowback by YES, and mutagenicity by AMES. The selective pressures of fracturing conditions (including toxicity) affected bacterial and archaeal communities, which were characterized by 16S rRNA gene V4V5 region sequencing. Conditions selected for thermophilic, anaerobic, halophilic bacteria and methanogenic archaea from the groundwater used for fracturing fluid, and from the native shale community. Trends in toxicity echoed the microbial community, which indicated distinct stages of early flowback water, a transition stage, and produced water. Biota in another sampled DJ Basin horizontal well resembled similarly aged samples from this well. However, microbial signatures were unique compared to samples from DJ Basin vertical wells, and wells from other basins. These data can inform treatability, reuse, and management decisions specific to the DJ Basin to minimize adverse environmental health and well production outcomes.

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Public concern is heightened around flowback and produced water (FPW) generated by the hydraulic fracturing process. FPW is a complex mix of organic and inorganic solutes derived from both the injected hydraulic fracturing fluid and interactions with the subsurface lithology. Few studies to date have systematically investigated the composition of FPW or its individual components. Here, we provide the first systematic characterization of the composition of the solids associated with FPW by analyzing samples from three wells drilled into the Duvernay Formation in Alberta, Canada. The FPW initially returned to the surface with high total dissolved solids (greater than 170 000 mg L−1) and enriched with Fe(II), silica, sulfate, barium, and strontium. The solids form two distinct phases once the FPW reached the surface: (1) silica-enriched Fe(III) oxyhydroxides, and (2) a barite–celestine solid solution. We hypothesize that the precipitation of the amorphous silica-enriched Fe(III) oxyhydroxide is a two-step process, where first the silica precipitates as a function of the cooling of the FPW from elevated subsurface temperatures to ambient surface temperatures. Next, the silica acts as a template for the precipitation of Fe(III) oxyhydroxide as the diffusion of oxygen into the subsurface causes oxidation of aqueous Fe(II). The barite–celestine solid solution precipitates solely as a function of cooling. Elevated dissolved Fe concentrations in FPW and modeled saturation indices from five North American shale plays (Marcellus, Fayetteville, Barnett, Bakken, and Denver-Julesburg) indicate that solids similar to those found in Duvernay FPW, specifically Fe(III) oxyhydroxides, barite and quartz, are likely to occur. With the solids known to carry a significant portion of FPW's toxicity and organic contaminant load, the development of new treatment technologies, such as the oxidation of the Fe(II) in FPW, may increase FPW reuse and reduce the environmental risk posed by FPW.

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Structured Abstract Background Oil and natural gas (O&G) extraction emits pollutants that are associated with cardiovascular disease, the leading cause of mortality in the United States. Objective: We evaluated associations between intensity of O&G activity and cardiovascular disease indicators. Methods Between October 2015 and May 2016, we conducted a cross-sectional study of 97 adults living in Northeastern Colorado. For each participant, we collected 1–3 measurements of augmentation index, systolic and diastolic blood pressure (SBP and DBP), and plasma concentrations of interleukin (IL)−1β, IL-6, IL-8 and tumor necrosis factor alpha (TNF-α). We modelled the intensity of O&G activity by weighting O&G well counts within 16km of a participant's home by intensity and distance. We used linear models accounting for repeated measures within person to evaluate associations. Results Adjusted mean augmentation index differed by 6.0% (95% CI: 0.6, 11.4%) and 5.1% (95%CI: −0.1, 10.4%) between high and medium, respectively, and low exposure tertiles. The greatest mean IL-1β, and α-TNF plasma concentrations were observed for participants in the highest exposure tertile.. IL-6 and IL-8 results were consistent with a null result. For participants not taking prescription medications, the adjusted mean SBP differed by 6 and 1mm Hg (95% CIs: 0.1, 13mm Hg and −6, 8mm Hg) between the high and medium, respectively, and low exposure tertiles. DBP results were similar. For participants taking prescription medications, SBP and DBP results were consistent with a null result. Conclusions Despite limitations, our results support associations between O&G activity and augmentation index, SBP, DBP, IL-1β, and TNF-α. Our study was not able to elucidate possible mechanisms or environmental stressors, such as air pollution and noise.

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Hydraulic fracturing has become a well-established and widespread technology for the extraction of oil and natural gas. Hydraulic fracturing fluids (HFFs) are widely varied and contain many chemicals that are toxic to human and ecological health. HFFs are often spilled on surface soils where their fate and transport is uncertain. In this study, six representative mixtures of HFFs were incubated with a surface soil in bench-scale microcosms, and the microbial community was analyzed over 78 days. The chemical oxygen demand decreased over time, although a significant recalcitrant fraction was found for four of the six amended fluids. With Illumina MiSeq sequencing of a 16S ribosomal RNA (rRNA) gene amplification and follow-through quantitative polymerase chain reaction (qPCR) assays, 24 bacterial taxa closely related to known species were identified to be enriched by at least one of the representative HFFs. These taxa are mostly closely related to well-known xenobiotic degraders, however, the composition of the enrichment was highly unique for each representative HFF. The results indicate that the complex mixtures of biocides and other components elicit unique bacterial community responses in the same soil, thus suggesting that the bioremediation pathways of HFF constituents in soils may differ based on exact HFF composition.

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Metagenomes from hydraulically fractured wells over time identified viral operational taxonomic units predicted to actively infect dominant bacteria, and in vitro experiments show that viral lysis of these hosts can release metabolites important for fermentation.

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In this era of global challenges in energy policy, the importance of siting of facilities connected to development of energy system is greater than ever. At the same time, spreading of these facilities has often been controversial in surrounding communities. This article advances the debate on this phenomenon by focusing on an aspect of siting controversies that has become a game changer in recent years but has received remarkably little attention: the role of Web 2.0 in siting conflicts. To explore the impact of Web 2.0, the paper uses a case study approach, examining the influence of access to the Internet in two siting conflicts associated with shale gas prospecting in Poland in the period from 2012 to 2014. The possibilities that Web 2.0 offers to residents and other local actors in siting conflicts - access to knowledge, the ability to reframe the local debate using international resources, and mobilization of a network of support by sharing their version of the story - influence the dynamics of risk communication during siting controversies.

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Hydraulic fracturing induces the shear failure of natural fracture which contributes to complex fracture network. The magnitude of fracture slip potentially causes some undesirable consequences including wellbore instability, casing deformation and fault reactivation. Therefore, it is important to predict the fracture slip induced by hydraulic fracturing for a safe and efficient stimulation. In this paper, we used a 2D hydro-mechanical coupled model to predict the injection-induced slip. The hydraulic and natural fractures are embedded in formations with cohesive zone model. The fracture propagation, rock deformation and wellbore slip displacement are captured in the 2D model. The wellbore slip displacement is input into a small-scale 3D mechanical model of casing in slip rock to simulate casing behavior. Casing curvature is also introduced to assess casing integrity. Results indicate that the rock deforms asymmetrically with respect to the wellbore after the shear failure of natural fracture. Particularly, there is a shear slip along the natural fracture. The simulation result shows that the casing failure mechanism is shear deformation induced by the fracture slip during hydraulic fracturing. The curvature of deformed casing is larger than that of directional well trajectory. The predicted results are validated by the logging and operation data from the field. This work provides a novel quantitative method for predicting fracture slip and evaluating well integrity during hydraulic fracturing.

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Potential effects of horizontal drilling combined with high-volume hydraulic fracturing (HF) have drawn significant public concern, especially on the handling, treatment, and disposal of HF flowback and produced water (HF-FPW). Previous studies indicated HF-FPW could significantly disrupt biotransformation and expressions of genes related to the endocrine system. This study focused on effects of organic extracts of HF-FPW on receptor binding activity using several transactivation assays. Six HF-FPW samples were collected from 2 wells (Well A and Well B, 3 time points at each well). These were separated by filtration into aqueous (W) and particulate (S) phases, and organics were extracted from all 12 subsamples. Of all the tested fractions, sample B1-S had the greatest Σ13PAH (11,000 ng/L) and B3-S has the greatest Σ4alkyl-PAHs (16,000 ng/L). Nuclear receptor binding activity of all the extracts on aryl hydrocarbon receptor (AhR), estrogen receptor (ER), and androgen receptor (AR) were screened using H4IIE-luc, MVLN-luc, and MDA-kb2 cells, respectively. FPWs from various HF wells exhibited distinct nuclear receptor binding effects. The strongest AhR agonist activity was detected in B3-S, with 450 ± 20 μg BaP/L equivalency at 5 × exposure. The greatest ER agonist activity was detected in A1-W, with 5.3 ± 0.9 nM E2 equivalency at 10× exposures. There is a decreasing trend in ER agonist activity from A1 to A3 in both aqueous and particulate fractions from Well A, while there is an increasing trend in ER agonist activity from B1 to B3 in aqueous fractions from Well B. This study provides novel information on the sources of endocrine disruptive potentials in various HF-FPW considering both temporal and spatial variability. Results suggest that reclamation or remediation and risk assessment of HF-FPW spills likely requires multiple strategies including understanding the properties of each spill with respect to fractured geological formation and physiochemical properties of the injected fluid.

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To inform sustainable energy development, it is important to understand the ecological effects of historical and current production practices and the persistence of those effects. The Williston Basin is one of North America's largest oil production areas and overlaps the Prairie Pothole Region, an area densely populated with wetlands that provide important wildlife habitat. Although historical disposal practices that released chloride-rich waters (brines) produced during oil extraction into the environment are no longer used, brine spills still occur frequently. We sampled 33 wetlands for three amphibian species in Montana and North Dakota during 2015–2017, primarily on National Wildlife Refuges, and used N-mixture models to determine how abundance varied with evidence of brine contamination. To provide insight into effects of historical versus contemporary contamination, we also estimated the association of well density and age with water quality and amphibian abundance. Abundance of boreal chorus frog (Pseudacris maculata) larvae declined most rapidly in response to increased chloride (range: 0.04–17,500 mg/L), followed by the northern leopard frog (Lithobates [Rana] pipiens) and barred tiger salamander (Ambystoma mavortium). Water quality and population- and community-level abundance of amphibians were more strongly related to nearby wells (≤800 m) installed before 1982 than to wells installed since 1982. These results suggest historical brine management practices were the primary driver of contamination and reduced amphibian abundance in wetlands we sampled, reflecting multi-decadal ecological effects. These persistent effects also underscore the critical need for tools to restore landscapes affected by brine contamination.

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Unconventional oil and gas development is achieved through a series of sub-processes, which utilize large amounts of water, proppant, and chemical additives to retrieve sequestered hydrocarbons from low permeability petroliferous strata. As a result, a large amount of wastewater is produced, which is traditionally disposed of via subsurface injection into non-productive stratum throughout the country. However, this method of waste management has been linked to the induction of seismic events in a number of regions across North America, calling into question the environmental stewardship and sustainability of subsurface waste disposal. Advancements in water treatment technologies have improved the efficacy and financial viability of produced water recycling for beneficial reuse in the oil and gas sector. This review will cover the various treatment options that are currently being utilized in shale energy basins to remove organic, inorganic, and biological constituents, as well as some emerging technologies that are designed to remove pertinent contaminants that would otherwise preclude the reuse of produced water for production well stimulation.

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Hydraulic fracturing (fracking) is a process used for the stimulation and production of ultra-low permeability shale gas and tight oil resources. Fracking poses two main risks to groundwater quality: (1) stray gas migration and (2) potential contamination from chemical and fluid spills. Risk assessment is complicated by the lack of predrilling baseline measurements, limited access to well sites and industry data, the constant introduction of new chemical additives to frack fluids, and difficulties comparing data sets obtained by different sampling and analytical methods. Specific recommendations to reduce uncertainties and meet science needs for better assessment of groundwater risks include improving data-sharing among researchers, adopting standardized methodologies, collecting predrilling baseline data, installing dedicated monitoring wells, developing shale-specific environmental indicators, and providing greater access to field sites, samples, and industry data to the research community.

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Shale gas development has been heralded as a game changer that has had, and will continue to have, repercussions for energy scenarios around the world, and natural gas has been hailed as the transition fuel to a low carbon future. Shale gas production-made feasible and economical by advances in hydraulic fracturing-offers a solution in the face of increased demand, instability in key producing regions, and societal aversion to the risks of nuclear energy. This "golden future," however, has come into conflict with increasing concerns over water. This paper examines policy and regulatory frameworks around hydraulic fracturing in Texas and Spain in order to consider the trade-offs-particularly at the expense of water security-that may occur as decision-makers pursue improvements in energy security. We compare regulatory, institutional, and cultural contexts in order to understand and evaluate the robustness of these frameworks to prevent the reduction in water security as a consequence of the pursuit of energy security. Paucity of data is discussed. We also consider questions such as disclosure of information to the public about water use or the chemical composition of frac fluids and public opinion about hydraulic fracturing. Lessons are drawn that may assist policymakers who seek to guarantee water security while pursuing energy security.

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Wastewater disposal is generally accepted to be the primary cause of the increased seismicity rate in Oklahoma within the past decade, but no statewide analysis has investigated the contribution of hydraulic fracturing (HF) to the observed seismicity or the seismic hazard. Utilizing an enhanced seismicity catalog generated with multistation template matching from 2010 to 2016 and all available hydraulic fracturing information, we identified 274 HF wells that are spatiotemporally correlated with bursts of seismicity. The majority of HF-induced seismicity cases occurred in the SCOOP/STACK plays, but we also identified prominent cases in the Arkoma Basin and some more complex potential cases along the edge of the Anadarko Platform. For HF treatments where we have access to injection parameters, modeling suggests that poroelastic stresses are likely responsible for seismicity, but we cannot rule out direct pore pressure effects as a contributing factor. In all of the 16 regions we identified, 75% of the seismicity correlated with reported HF wells. In some regions, >95% of seismicity correlated with HF wells and >50% of the HF wells correlated with seismicity. Overall, we found similar to 700 HF-induced earthquakes with M2.0, including 12 events with M 3.0-3.5. These findings suggest state regulations implemented in 2018 that require operators in the SCOOP/STACK plays to take action if a M>2 earthquake could have a significant impact on future operations.

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In this study we present a spatiotemporal analysis of the recent seismicity and industry-related wastewater injection activity in Oklahoma. A parsimonious predictive tool was developed to estimate the lagged effect of previous month’s injection volumes on subsequent regional seismic activity. Results support the hypothesis that the recent boom in unconventional oil and gas production and either the mitigation policies or the drop in oil prices (or both) are potentially responsible for the upsurge and reduction in the state’s seismic activity between 2006–2015 and 2016–2017, respectively. A cluster analysis reveals a synchronous migration pattern between earthquake occurrences and salt water injection with a predominant northwest direction during 2006 through 2017. A lagged cross-correlation analysis allows extracting a power law between expected number of quakes and weighted average monthly injection volumes with a coefficient of determination of R2 = 0.77. Such a relation could be used to establish “sustainable water injection limits” aiming to minimize seismicity to values comparable with several historically representative averages. Results from these analyses coincide on previously found sustainable limits of 5 to 6 million m3/month but expand to operations that could attain the same number through differential monthly planning. Findings could potentially be used for model intercomparison and regulation policies.

Abstract:
In the western U.S., produced water from oil and gas wells discharged to surface water augments downstream supplies used for irrigation and livestock watering. Here we investigate six permitted discharges on three neighboring tributary systems in Wyoming. During 2013–16, we evaluated radium activities of the permitted discharges and the potential for radium accumulation in associated stream sediments. Radium activities of the sediments at the points of discharge ranged from approximately 200–3600 Bq kg−1 with elevated activities above the background of 74 Bq kg−1 over 30 km downstream of one permitted discharge. Sediment as deep as 30 cm near the point of discharge had radium activities elevated above background. X-ray diffraction and targeted sequential extraction of radium in sediments indicate that radium is likely coprecipitated with carbonate and, to a lesser extent, sulfate minerals. PHREEQC modeling predicts radium coprecipitation with aragonite and barite, but over-estimates the latter compared to observations of downstream sediment, where carbonate predominates. Mass-balance calculations indicate over 3 billion Bq of radium activity (226Ra + 228Ra) is discharged each year from five of the discharges, combined, with only 5 percent of the annual load retained in stream sediments within 100 m of the effluent discharges; the remaining 95 percent of the radium is transported farther downstream as sediment-associated and aqueous species.

Abstract:
We related Louisiana Waterthrush (Parkesia motacilla) demographic response and nest survival to benthic macroinvertebrate aquatic prey and to shale gas development parameters using models that accounted for both spatial and non-spatial sources of variability in a Central Appalachian USA watershed. In 2013, aquatic prey density and pollution intolerant genera (i.e., pollution tolerance value <4) decreased statistically with increased waterthrush territory length but not in 2014 when territory densities were lower. In general, most demographic responses to aquatic prey were variable and negatively related to aquatic prey in 2013 but positively related in 2014. Competing aquatic prey covariate models to explain nest survival were not statistically significant but differed annually and in general reversed from negative to positive influence on daily survival rate. Potential hydraulic fracturing runoff decreased nest survival both years and was statistically significant in 2014. The EPA Rapid Bioassessment protocol (EPA) and Habitat Suitability Index (HSI) designed for assessing suitability requirements for waterthrush were positively linked to aquatic prey where higher scores increased aquatic prey metrics, but EPA was more strongly linked than HSI and varied annually. While potential hydraulic fracturing runoff in 2013 may have increased Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness, in 2014 shale gas territory disturbance decreased EPT richness. In 2014, intolerant genera decreased at the territory and nest level with increased shale gas disturbance suggesting the potential for localized negative effects on waterthrush. Loss of food resources does not seem directly or solely responsible for demographic declines where waterthrush likely were able to meet their foraging needs. However collective evidence suggests there may be a shale gas disturbance threshold at which waterthrush respond negatively to aquatic prey community changes. Density-dependent regulation of their ability to adapt to environmental change through acquisition of additional resources may also alter demographic response.

Abstract:
Shale gas extraction through hydraulic fracturing and horizontal drilling is increasing in China, particularly in Sichuan Basin. Production of unconventional shale gas with minimal environmental effects requires adequate management of wastewater from flowback and produced water (FP water) that is coextracted with natural gas. Here we present, for the first time, inorganic chemistry and multiple isotope (oxygen, hydrogen, boron, strontium, radium) data for FP water from 13 shale gas wells from the Lower Silurian Longmaxi Formation in the Weiyuan gas field, as well as produced waters from 35 conventional gas wells from underlying (Sinian, Cambrian) and overlying (Permian, Triassic) formations in Sichuan Basin. The chemical and isotope data indicate that the formation waters in Sichuan Basin originated from relics of different stages of evaporated seawater modified by water-rock interactions. The FP water from shale gas wells derives from blending of injected hydraulic fracturing water and entrapped saline (Cl ∼ 50,000 mg/L) formation water. Variations in the chemistry, δ18O, δ11B, and 87Sr/86Sr of FP water over time indicate that the mixing between the two sources varies with time, with a contribution of 75% (first 6 months) to 20% (>year) of the injected hydraulic fracturing water in the blend that compose the FP water. Mass-balance calculation suggests that the returned hydraulic fracturing water consisted of 28-49% of the volume of the injected hydraulic fracturing water, about a year after the initial hydraulic fracturing. We show differential mobilization of Na, B, Sr, and Li from the shale rocks during early stages of operation, which resulted in higher Na/Cl, B/Cl, Li/Cl, and 87Sr/86Sr and lower δ11B of the FP water during early stages of FP water formation relative to the original saline formation water recorded in late stages FP water. This study provides a geochemical framework for characterization of formation waters from different geological strata, and thus the ability to distinguish between different sources of oil and gas wastewater in Sichuan Basin.

Abstract:
In 2011, Maryland established the Marcellus Shale Safe Drilling Initiative to determine whether and how gas production in the state could be accomplished without causing unacceptable risks to public health, safety, natural resources, and the environment. This initiative required a statewide health impact assessment of unconventional natural gas development and production via hydraulic fracturing (i.e., fracking). Increasing number of studies have shown that fracking has significant potential to impact health and non-health outcomes. However, because of its rapid development, there is a lack of substantive research related to the public health effects of fracking. I discuss my firsthand experiences as a medical anthropologist and public health researcher on a multi-disciplinary research team tasked with conducting Maryland’s first health impact assessment to determine the potential public health impacts associated with fracking. I focus on how fracking, as a relatively new economically viable source of energy and an emergent focus of study, brings about public and scientific anxieties, and how these anxieties shape subsequent environmental and health policy decision making processes. I reflect on the potential role of social scientists in matters of scientific knowledge production and resulting policy decisions and the broader implications of such engagement for public social science.

Abstract:
Extensive development of shale gas has generated some concerns about environmental impacts such as the migration of natural gas into water resources. We studied high gas concentrations in waters at a site near Marcellus Shale gas wells to determine the geological explanations and geochemical implications. The local geology may explain why methane has discharged for 7 years into groundwater, a stream, and the atmosphere. Gas may migrate easily near the gas wells in this location where the Marcellus Shale dips significantly, is shallow (∼1 km), and is more fractured. Methane and ethane concentrations in local water wells increased after gas development compared with predrilling concentrations reported in the region. Noble gas and isotopic evidence are consistent with the upward migration of gas from the Marcellus Formation in a free-gas phase. This upflow results in microbially mediated oxidation near the surface. Iron concentrations also increased following the increase of natural gas concentrations in domestic water wells. After several months, both iron and SO42− concentrations dropped. These observations are attributed to iron and SO42− reduction associated with newly elevated concentrations of methane. These temporal trends, as well as data from other areas with reported leaks, document a way to distinguish newly migrated methane from preexisting sources of gas. This study thus documents both geologically risky areas and geochemical signatures of iron and SO42− that could distinguish newly leaked methane from older methane sources in aquifers.

Abstract:
Potential impacts of shale gas development on shallow aquifers has raised concerns, especially regarding groundwater contamination. The intermediate zone separating shallow aquifers from shale gas reservoirs plays a critical role in aquifer vulnerability to fluid upflow, but the assessment of such vulnerability is challenging due to the general paucity of data in this intermediate zone. The ultimate goal of the project reported here was to develop a holistic multi-geoscience methodology to assess potential impacts of unconventional hydrocarbon development on fresh-water aquifers related to upward migration through natural pathways. The study area is located in the St. Lawrence Lowlands (southern Quebec, Canada), where limited oil and gas exploration and no shale gas production have taken place. A large set of data was collected over a ∼500 km2 area near a horizontal shale gas exploration well completed and fracked into the Utica Shale at a depth of ≈2 km. To investigate the intermediate zone integrity, this project integrated research results from multiple sources in order to obtain a better understanding of the system hydrodynamics, including geology, hydrogeology, deep and shallow geophysics, soil, rock and groundwater geochemistry, and geomechanics. The combined interpretation of the multi-disciplinary dataset demonstrates that there is no evidence of, and a very limited potential for, upward fluid migration from the Utica Shale reservoir to the shallow aquifer. Microbial and thermogenic methane in groundwater of this region appear to come from the shallow, organic-rich, fractured sedimentary rocks making up the regional aquifer. Nonetheless, diluted brines present in a few shallow wells close to and downstream of a normal fault revealed that some upward groundwater migration occurs, but only over a few hundred meters from the surface based on the isotopic signature of methane. This work should help support regulations related to shale gas development aiming to protect groundwater.

Abstract:
In order to survive environmental changes, bacteria have stress responses, which protect them from adverse and variable conditions. Contamination can be a source of stress and bacterial responses can serve as an indicator of environmental abnormality. In this work, the biochemical effects of toxic compounds that stem from hydraulic fracturing were measured on the whole cell-derived fatty acid and protein compositions of Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa, Pseudomonas putida, Pseudomonas stutzeri, Aeromonas hydrophila, Bacillus cereus, and Bacillus subtilis. These microorganisms were exposed to elevated levels of benzene, ethanol, propanol, toluene, and salt. These were chosen to represent significant subsurface contamination or a surface spill. The fatty acid and protein profiles for the bacteria were analyzed using gas chromatography – vacuum ultraviolet spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry, respectively. Overall, different fatty acid and protein profiles were observed when the microorganisms were grown in the presence of the toxic compounds. The cells exhibited an increase in the saturated/unsaturated ratio and displayed the presence of branched and cyclopropane fatty acids when in the presence of common fracture fluid constituents to decrease membrane permeability which was confirmed by the analysis of produced water. This approach provides a potentially useful tool for environmental diagnosis, since proteins and fatty acids can act as a harbinger of ecological health.

Abstract:
Hydraulic fracturing generates large volumes of produced water, and treatment of produced water may be necessary for disposal or reuse. Biological treatment of produced water is a potential approach to remove organic constituents and reduce fouling, in conjunction with other treatment processes. This study investigates the biological treatability of produced water samples from the Utica and Bakken Shales using engineered biofilms. Observed total dissolved organic carbon (DOC) removal varied between 1-87% at normalized total dissolved solids concentrations, suggesting that the composition of produced water, including organic constituents and trace elements such as nutrients and metals, is an important driver of biological treatment performance. Mass spectrometric analyses of the DOC composition revealed various alkanes in all samples, but differences in non-ionic surfactant, halogenated, and acidic compound content. Statistical data reduction approaches suggest that the latter two groups are correlated with reduced biodegradation kinetics. These results demonstrate that the combination of biodegradation performance and organic speciation can guide the assessment of the biological treatment of produced water.

Abstract:
Potential for shale gas production is linked to regional geology, which influences water chemistry of freshwater systems. However, there has been little work to establish baseline ecological conditions of rivers within areas of shale gas development. In this study, water chemistry and monitoring metrics for fish and benthic macroinvertebrates were compared among varying-sized streams in New Brunswick, Canada with different underlying geology. Water chemistry and biotic community structure differed strongly among geological age classes. Early Carboniferous stations, with highest potential for shale gas production, had the highest ions, invertebrate abundances, and richness of invertebrates and fish, with strongest differences between Early Carboniferous and older bedrock classes. A reference condition model indicated numerous sites deviated from normal, but this was not specific to geological classes, and reflected the lack of model reference site coverage. These results highlight the importance of selecti...

Abstract:
We examine ‘fracking’ for shale gas extraction in England, France, and Algeria, framed from the perspective of level of acceptance by communities and general public. We explore the extent to which public participation in decision-making should play a role in fracking regulation, and evaluate whether the level of public participation matches the legal requirements. Our position on the adequacy of fracking regulation is from the perspective of the public dissenter, outlining a legal and normative basis for public participation in decision-making on fracking. We highlight relevant laws and policies to understand and evaluate adequacy of relevant regulatory processes. We offer strong yet nuanced argumentation, creating space for further discussion by academics, the public, regulators, local decision-makers, fracking companies and others. This is not a typical social-psychology, legal, sociology, or human geography research paper, as we take a position from the beginning: that the public ought to be involved in decisions related to the regulation of fracking, and argue that we validate our approach by supporting our claims throughout the work.

Abstract:
Unconventional oil and gas extraction (UOG) has expanded rapidly across the United States, as it has become an established technique for oil and gas extraction from low permeability shales. There are more than 900,000 active oil and gas wells in the United States, and more than 130,000 have been drilled since 2010.1 The U.S. Energy Information Administration (EIA) estimates that in 2017, about 16.76 trillion cubic feet (Tcf) of dry natural gas was produced from shale resources in the United States, including the Bakken (North Dakota and Montana), Niobrara (Colorado), Marcellus and Utica (Pennsylvania, Ohio, and West Virginia), Haynesville (Louisiana and East Texas), Eagle Ford (South Texas), and Permian Basin (West Texas and Southeast New Mexico) shale plays.

Abstract:
Over the past decade, the U.S. has had significant growth in oil and gas production due in large part to hydraulic fracturing ("fracking"); and yet, we know little about public preferences for oil and gas regulations. Political identity is a strong predictor of policy support in other arenas. The purpose of this analysis is to clarify the role of political identity in support for oil and gas policy. We hypothesized that political identity has a direct impact on policy support and an indirect impact via risk/benefit perceptions and trust in the oil and gas industry. Using the KHB mediation technique, we show that about half of the impact of political identity is indirect via these mediating variables. We suggest that political identity is a uniquely important factor in environmental governance because it impacts both policy preferences and other variables that, in turn, also explain policy preferences. Political identity appears to be salient, even for local governance controversies.

Abstract:
This paper situates the question of shale gas mining in South Africa within broader debates on policy co-ordination within governmental systems. The prospect of shale gas mining has posed severe challenges for the complex inter-governmental system in South Africa. Three key Departments are affected by possible shale gas mining: Mineral Resources, Environmental Affairs and Water Resources. Each of these Departments have different relationships with the provincial and municipal "spheres of government". The Department of Mineral Resources has attempted to promote shale gas mining with no reference to municipalities, whereas the other two Departments have attempted to build up municipal capacity. Municipalities have key functions which are protected in the Constitution. However, many municipalities are weak institutions, unwilling to defend their powers. The paper examines Municipal Integrated Development Plans in the potential shale gas region. Most municipalities seem to have no awareness at all of the shale gas issue. Recently, a High Court ruled that any shale gas mining regulations must be made by the Department of Environmental Affairs. With its more decentralist approach to governance, it will mean that municipalities will have more opportunities to participate in shale gas mining decisions.

Abstract:
Over the past two decades, the U.S. energy sector has undergone significant transition. Coal— historically the primary power source for the U.S. economy—has declined markedly in both production and consumption. Renewables like wind and solar have become much more economically viable in recent years. However, perhaps the most dramatic change has been the drastic increase in oil and gas production since the mid-2000s, due largely to the convergence of unconventional technologies like hydraulic fracturing and directional drilling. The changing energy system presents both opportunities and challenges for local governments, especially those in rural areas that face unique fiscal struggles. In this paper, we present results of a survey of local policy actors in the Mountain West states of Colorado and Utah. Policy actors assessed the fiscal and public service impacts of different types of energy development and we tie these survey responses to spatial energy development data. Results imply that policy actors have nuanced views of all types of energy, though fossil fuels (especially coal) are generally seen as more fiscally beneficial than renewables. Generally, the spatial proximity of a type of energy development has only a weak relationship with perceived fiscal and public service costs and benefits.