Repository for Oil and Gas Energy Research (ROGER)

Abstract:
Hydraulic fracturing creates large volumes of flowback and produced water (FPW). The waste is a complex mixture of organic and inorganic constituents. Although the acute toxicity of FPW to freshwater organisms has been studied, few have attempted to discern the interaction between organic and inorganic constituents within this matrix and its role in toxicity. In the present study, bioaccumulation assays (7-d uptake and 7-d elimination period) with FPW (1% dilution) were conducted with the freshwater oligochaete, Lumbriculus variegatus, to evaluate the toxicokinetics of inorganic elements. To evaluate the interacting role of organics, bioaccumulation of elements in unmodified FPW was compared to activated carbon treated FPW (AC-modified). Differences in uptake and elimination rates as well as elimination steady state concentrations between unmodified and AC-modified treatments indicated that the organics play an important role in the uptake and depuration of inorganic elements in FPW. These differences in toxicokinetics between treatments aligned with observed growth rates in the worms which were higher in the AC-modified treatment. Whether growth differences resulted from increased accumulation and changes in toxicokinetic rates of inorganics or caused by direct toxicity from the organic fraction of FPW itself is still unknown and requires further research.

Abstract:
This study investigated the removal of organic compounds from shale gas fracturing flowback water (FFW) by an integrated electro-coagulation and electro-peroxone (EC-EP) process in a divided electrochemical reactor. During the EC-EP process, electricity was efficiently utilized to produce both aluminum ion (Al3+) from electrochemical oxidation of an aluminum anode in the anodic compartment and hydrogen peroxide (H2O2) from oxygen reduction at a carbon-based cathode in the cathodic compartment. The in-situ generated H2O2 then reacted with ozone (O3) sparged in the cathodic compartment to produce hydroxyl radicals (•OH) for pollutant oxidation. The results showed that by sequentially treating the selected FFW by the EC and EP process in the anodic and cathodic compartment for 30 min, respectively, the EC-EP process effectively removed ~95% of total organic carbon (TOC) from the FFW, meeting the wastewater discharge standard for TOC (≤30 mg/L) with a low specific energy consumption of 0.11–0.21 kWh/g TOC removed. In contrast, individual EC and EP process, as well as the previously investigated ECP process that combined the EC and EP process in an undivided reactor, removed only ~76%, 32%, and 80% TOC from the FFW under similar reaction conditions, and thus could not meet the wastewater discharge standard. These results demonstrate that the EC-EP process successfully integrates the merit of the EC and EP process and may thus provide a cost-effective way to remove organic compounds for FFW disposal and reuses.

Abstract:
The UK government's policy of support for shale gas extraction ended in November 2019 with the imposition of a moratorium on fracking (hydraulic fracturing) in England, and an admission that the policies to manage induced seismicity were insufficient. However, ambiguities remain regarding its scope, despite attempts at clarification. The concept of fracking to improve hydrocarbon production has evolved from defining a specific engineering process, using high volumes of water, to encompass other ‘unconventional’ methods to achieve the same end. We resolve the various definitions in a scientific, technical, regulatory and legislative context, robustly define unconventional extraction methods (circumventing the need to identify and quantify the various technologies available), and advocate the precautionary principle in drafting and interpreting regulations. Policy should be driven by the engineering of the bulk physical characteristics of the target rock, rather than by the current definitions based on injected fluid volume. To meet climate change concerns, the moratorium should be converted into a ban. In the interim, we argue that, in order to comply with the government's policy of ensuring safe and sustainable operations, the moratorium should be extended to all well stimulation treatments for unconventional hydrocarbon extraction, including acid stimulation.

Abstract:
Significant increases in seismic activity have been recorded since fracturing and extraction began in 2014 in the Changning shale gas development block that is located in the Southern Sichuan Basin, China (SSBC). The primary aim of this paper was to assess the hazard and risk (HR) resulting from the induced seismicity via the Entropy-Fuzzy-AHP (E-FAHP) method. The assessment used for this study was carried out for 2700 grids with a total area of 1089 km2. The results were combined to form a regional earthquake HR map. Firstly, a large amount of raw data was collected and analyzed and six core factors were selected to form the index layers of the model. The b-value and Z-value derived from seismology indicate the level of historical seismic activity, the faults and fractures that reflect the regional structural instability, as well as two human activities that may induce seismicity: hydraulic fracturing and reservoir storage. Secondly, the evaluation criteria and the membership matrix were established, and the objective weight of each grid was obtained by using the Entropy model. Meanwhile, the subjective weight of each factor was calculated under the AHP expert scoring method, and the subjective and objective weight coupling was performed. Thirdly, the fuzzy product of the weight and the membership matrix produced the final evaluation of the grid. Based on different evaluation years, the model was divided into three classifications, among which Classification 1 has a better prediction effect than Classification 2 and can predict the precise occurrence range of new earthquakes. After correcting the combination modes of the initial data of the fracturing platform factors, the Classification 2 prediction effect was greatly improved. This study shows that as long as the key factors are thoroughly understood, the HR of induced earthquake can be predicted and controlled.

Abstract:
Understanding the speciation and fate of radium during operational discharge from the offshore oil and gas industry into the marine environment is important in assessing its long term environmental impact. In the current work, 226Ra concentrations in marine sediments contaminated by produced water discharge from a site in the UK were analysed using gamma spectroscopy. Radium was present in field samples (0.1–0.3 Bq g−1) within International Atomic Energy Agency activity thresholds and was found to be primarily associated with micron sized radiobarite particles (≤2 μm). Experimental studies of synthetic/field produced water and seawater mixing under laboratory conditions showed that a significant proportion of radium (up to 97%) co-precipitated with barite confirming the radiobarite fate pathway. The results showed that produced water discharge into the marine environment results in the formation of radiobarite particles which incorporate a significant portion of radium and can be deposited in marine sediments.

Abstract:
The oilfield produced water is a major waste stream in places where shale-gas production is growing rapidly. The reuse of produced water merits consideration because this practice helps reduce freshwater demand for fracking and moderates water pollution. Knowledge about the chemistry of produced water is needed to develop sustainable treatment/reuse strategies and set standards for acceptable levels of treatment of produced water. Thus, the author performed the first comprehensive analysis of oilfield produced water collected from the Bakken shale play in the U.S. state of North Dakota that represents the nation's third-largest net increase in proven crude oil reserves. The concentrations of a total of 36 elements in 13 IUPAC groups were determined. Among them, a few metals that are critical to the economy of the United States were detected at elevated concentrations (median, mg/L): K (7,620), Mg (2780), Sr (1610), Li (69), and Mn (33). Heavy metals essential for plants and animals, including Cu, Zn, and Mn, were detected at ppm levels. Measurable concentrations of highly toxic metal ions such as Cd and Pb were not detected. Concentrations of rare earth elements and platinum group metals were below respective detection limits. The produced water samples had very high total dissolved solids (237,680 ± 73,828 mg/L) and total hardness (>31,000 mg/L as CaCO3) but an extremely low alkalinity (152.4 ± 184.9 mg/L as CaCO3); therefore, softening by lime and soda was ineffective. Softening by caustic soda removed 99.5% hardness ions (Ca and Mg) under alkaline conditions. This study provides vital insight into the chemistry and treatability of produced water containing various metals.

Abstract:
Diluted bitumen, also known as dilbit, is transported by rail and pipeline across Canada and the United States. Due to the fewer number of studies characterizing the toxicity of dilbit, a dilbit spill poses an unknown risk to freshwater aquatic ecosystems. In the following study, we compared the impact of early-life exposure to conventional and unconventional crude oils on the optomotor behavior, reproductive success, and transgenerational differences in gene expression in zebrafish and their progeny. For exposures, water accommodated fractions (WAFs) of crude oil were generated using a 1:1000 oil to water ratio for 3 different crudes; mixed sweet blend (MSB), medium sour composite (MSC) and dilbit. All three oils generated unique volatile organic compound (VOC) and polycyclic aromatic compound (PAC) profiles. Of the WAFs tested, only dilbit decreased the eye size of 2 dpf larvae, and only MSB exposed larvae had an altered behavioral response to a visual simulation of a predator. Early-life exposure to crude oil had no lasting impact on reproductive success of adult fish; however, each oil had unique impacts on the basal gene expression of the somatically exposed offspring. In this study, the biological effects differed between each of the oils tested, which implied chemical composition plays a critical role in determining the sublethal toxicity of conventional and unconventional crude oils in freshwater ecosystems.

Abstract:
Recent natural gas development by means of hydraulic fracturing requires a detailed risk analysis to eliminate or mitigate damage to the natural environment. Such geo-energy related subsurface activities involve complex engineering processes and uncertain data, making comprehensive, quantitative risk assessments a challenge to develop. This research seeks to develop a risk framework utilising data for quantitative numerical analysis and expert knowledge for qualitative analysis in the form of fuzzy logic, focusing on hydraulically fractured wells during the well stimulation stage applied to scenarios in the UK and Canada. New fault trees are developed for assessing cement failure in the vertical and horizontal directions, resulting in probabilities of failure of 3.42% and 0.84%, respectively. An overall probability of migration to groundwater during the well injection stage was determined as 0.0006%, compared with a Canadian case study which considered 0.13% of wells failed during any stage of the wells life cycle. It incorporates various data types to represent the complexity of hydraulic fracturing, encouraging a more complete and accurate analysis of risk failures which engineers can directly apply to old and new hydraulic fracturing sites without the necessity for extensive historic and probabilistic data. This framework can be extended to assess risk across all stages of well development, which would lead to a gap in the modelled and actual probabilities narrowing. The framework developed has relevance to other geo-energy related subsurface activities such as CO2 sequestration, geothermal, and waste fluid injection disposal.

Abstract:
The expansion of unconventional oil and gas development (UNGD) in the US has been highly controversial so far with no consensus on its health, economic, environmental, and social implications. This paper examines the effects of UNGD on the health profile of the population in the context of Oklahoma using a unique data set. To this end, the analysis assembles a panel data set including 76 counties of Oklahoma, spanning the period 1998–2017. The analysis estimates the long-run relationship between the health profile and its determinants using the Common Correlated Effects (CCE) method. The empirical setup allows for cross-sectional dependence and accounts for both observed and unobserved heterogeneity. The main findings provide strong evidence that UNGD activities have negative effects on human health-related outcomes across all counties in Oklahoma. Specifically, an increase in the number of (unconventional) wells has a positive impact on mortality rates, and incidences of cancer, cardiac, and respiratory diseases in communities in close spatial proximity, and a negative impact on life expectancy. These findings provide evidence that UNGD activities pose significant risks to the public health profile across the Oklahoma population. Such findings are expected to have substantial implications for the national debate on the regulation of UNGD.

Abstract:
A relatively new term for categorizing hazards is that of “techna” hazards, or seemingly natural phenomena induced by human technology or activity. The human origin of these hazards means that mitigation aimed at addressing the underlying cause of the hazard is a possibility, which is often not considered possible with traditional natural hazards. Currently, however, there is a dearth of literature regarding how perceptions of the underlying cause of the hazard influences beliefs regarding disaster risk reduction strategies for the hazard. Thus, this work examines the factors that predict beliefs regarding whether a techna hazard can be stopped or reduced, the best actions that should be taken to reduce or stop the hazard event, and whether current regulation efforts aimed at stopping or controlling the activities causing the hazard are enough. We specifically examine the case of fluid injection induced seismicity in Oklahoma and Colorado in the United States. We find that, contrary to our expectations from prior literature, exposure to the hazard is not a strong predictive factor of these beliefs. Perceptions of the underlying activity associated with the hazard, in this case hydraulic fracturing and oil and gas development, is significant, in that those with more positive views of the industry activity are more likely to believe the earthquakes cannot be stopped and favor less intense regulative efforts to address the hazard.

Abstract:
Despite the growing body of studies on the various fracturing phrases, the research on the differences between subterranean and surface microorganisms at shale gas drilling sites is still limited. Generally, shale gas development and the production process are divided into drilling and fracturing. The distribution of microbial communities in the latter has been paid some attention, but a deficit remains in terms of our understanding of the microbial community in the former, especially for the phase of drilling flowback and drilling flowback surface. In this study, four drilling flowback fluids (DFFs) (H230-flowback drilling cuttings, H23G-flowback drilling mud, H240-flowback drilling sediment, and H21F-flowback drilling water) from the outlet of subterranean pipeline to the inlet of storage tank were successively collected from H2 shale gas field during its initial drilling in Sichuan, China. Natural mountain water (H10W) used as the injection water of H2 was also sampled. Illumina MiSeq 16S rRNA gene sequencing revealed a total of 8 phyla, 17 classes, 35 orders, 61 families, and 98 genera that were recovered from these samples with uneven distribution. The majority of the obtained sequences belonged to the phyla Proteobacteria (75.36%), Bacteroidetes (10.75%), and Firmicutes (5.64%), with significant differences found in DFFs and injection water. The richness of microorganisms gradually increased with the increasing flowback flowing distance (H230< H23G< H240< H21F< H10W), which was employed to reveal a rapid change in microbiota that was evident in samples along the flow path aboveground from a depth of 3548 m. The findings of this study could expand our understanding of the ecological role of microorganisms during the shale gas drilling phase. Furthermore, the study highlights the temporal-spatial trajectory of microbial communities from subterranean environments to the surface in a short period of 30 days.

Abstract:
Poland has been estimated to possess large volumes of technically recoverable shale gas resources, which has raised national hopes for increasing energy security and building export capacity. In this paper, we aim to examine political claims and hopes that Poland could achieve natural gas self-sufficiency and even become a gas exporter by harnessing domestic shale potential. We do so by relying on well-by-well production experience from the Barnett Shale in the USA to explore what scope of shale gas extraction, in terms of the number of wells, would likely be required to achieve such national expectations. With average well productivity equal to the Barnett Shale, at least 420 wells per year would be necessary to meet the domestic demand of 20 Bcm in 2030. Adding Poland’s potential export capacity of five Bcm of gas per year would necessitate at least 540 wells per year. Such a significant amount of drilling and hydraulic fracturing would require reconsideration and verification of national energy security plans and expectations surrounding shale gas production. A more informed public debate on technical aspects of extraction would be required, as extensive fracking operations could potentially have implications in terms of environmental risks and local land-use conflicts.

Abstract:
Understanding the behavior and composition of fracturing flowback water (FFW) can provide insight into in situ water–rock interactions, assessment of the success of the fracturing operations. FFW was collected from three wells (Z202-H1, Z203, and Z205) for up to 108 days after fracturing in the same area of western Chongqing, China. The samples were analyzed for the concentrations of various ions (Na+, K+, Ca2+, Mg2+, Ba2+, Sr2+, Cl−, SO42−, Br−, HCO3−, etc.) and for the stable isotope composition (δD and δ18O) of water. With increasing flowback time, the ionic concentration and total salinity increased (e.g., from 315 mg/L to 37117 mg/L after 38 days for well Z203), stable isotopic ratios became heavier (e.g., δD values changed from −23.59‰ to −14.32‰, δ18O values changed from −3.91‰ to −1.92‰). The total salinity of the FFW is shown to be the result of mixing of the highly saline formation water and the low-salinity fracturing water. FFW from Z205 had higher concentrations of Li+ and NO3−, heavier stable isotope compositions, larger Na+/Cl− ratio, smaller (Cl−-Na+)/Mg2+ ratio, and larger SO42− × 100/Cl− ratio compared to the other two wells. All these phenomena revealed that Z205 is more likely to contact with active aquifers which is not conducive to natural gas preservation, because Z205 is close to (less 300 m from) a grade II fault. The RITS and RSIH with flowback time in Z203 were higher than Z202-H1, which shows that FFW from Z203 contained a greater fraction of formation water released from pores or fractures due to complex the network fractures formed by fracturing. Therefore, the fracturing operations of Z203 is better than Z202-H1. This result can reveal the reason for the production difference of adjacent wells, which is difficult to explain by similar total SRV.

Abstract:
China has stepped up its oil and gas development including unconventional resources as foreign dependence for oil and gas increased. Environmental impacts from the development phase has also caused widespread concern. To better understand environment impacts from current oil and gas development in China, a hybrid life cycle analysis (H-LCA) model was used to estimate the impact of six fields at the development stage based on data from 2017. The full environmental impact and full impact intensity (i.e., full environmental impact per unit of output by calorific value) of shale gas, conventional natural gas and oil development in China was compared and analyzed by eliminating well depth. Shale gas has 12.5% more environmental impact than conventional natural gas. Environmental impact of natural gas development is roughly 1.5 to 2 times that of conventional oil. Development of gas in Sichuan Basin have the greatest environmental impact, following southeast coast, Song Liao Basin, and Junggar Basin. However, the full impact intensity of shale gas development is more than five times that of conventional natural gas, but natural gas is still greener than conventional oil. The greatest full impact intensity is found in Junggar Basin, following Song Liao Basin and southeastern coast. From the comparison of full environmental impact and full impact intensity under per well depth, it's found that both of these are not positively correlated with reservoir depth and well depth even in the same basin. More attention should be paid to driving effects of specific reservoir developments and geological conditions.

Abstract:
Drawing on ethnographic research in two locations facing the prospect of shale gas exploration in Poland and the UK, I analyse how the future can be simultaneously predetermined and undetermined. Local actors handle this complex experience by relating to fracking infrastructures, fixing the materialities of shale gas as well as cultivating an air of conspiracy around the intricacies of gas developments. I focus on the everyday to broaden the scope of recent scholarly writing on resource indeterminacy that explores how corporate strategies create the futures of resource extraction. The contradictory temporalities that these strategies generate have to be reconciled at the sites of extraction. I call for opening our theorisations up to how resource indeterminacy and assertions of predetermined futures are mediated in the everyday contexts of noncorporate actors. By considering these daily forms of engagement with resource exploration, we gain a more realistic perspective on the potentialities of extraction.

Abstract:

Abstract. The United States has experienced a sharp increase in unconventional natural gas (UNG) development due to the technological development of hydraulic fracturing. The objective of this study is to investigate the emissions at an active Marcellus Shale well pad at the Marcellus Shale Energy and Environment Laboratory (MSEEL) in Morgantown, West Virginia, USA. Using an ambient air monitoring laboratory, continuous sampling started in September 2015 during horizontal drilling and ended in February 2016 when wells were in production. High-resolution data were collected for the following air quality contaminants: volatile organic compounds (VOCs), ozone (O₃), methane (CH₄), nitrogen oxides (NO and NO₂), and carbon dioxide (CO₂), as well as typical meteorological parameters (wind speed and direction, temperature, relative humidity, and barometric pressure). Positive matrix factorization (PMF), a multivariate factor analysis tool, was used to identify possible sources of these pollutants (factor profiles) and determine the contribution of those sources to the air quality at the site. The results of the PMF analysis for well pad development phases indicate that there are three potential factor profiles impacting air quality at the site: natural gas, regional transport/photochemistry, and engine emissions. There is a significant contribution of pollutants during the horizontal drilling stage to the natural gas factor. The model outcomes show that there is an increasing contribution to the engine emission factor over different well pad drilling periods through production phases. Moreover, model results suggest that the regional transport/photochemistry factor is more pronounced during horizontal drilling and drillout due to limited emissions at the site.

Abstract:
Over the past two decades, hydraulic fracturing, commonly known as ‘fracking’, in Colorado has increased crude oil and natural gas production exponentially. This growth continues to benefit the Colorado economy and employs hundreds of thousands of residents across the state (U.S. EIA 2020a; Hochman 2019). However, despite these economic benefits, studies over the past ten years demonstrate that fracking presents serious environmental and human health risks, particularly to those who live near wells. Hydraulically fractured wells can release toxic hydrocarbons into the atmosphere as well as contaminate land and water supplies, which puts Colorado residents living within 1 kilometer of these wells at an increased risk for adverse dermal and upper respiratory symptoms (Jackson et al. 2014, 347-348; Rabinowitz et al. 2015, 25). Additionally, people living within ½ mile of a well are at an increased risk for developing cancer (McKenzie et al. 2012, 85). Colorado Senate Bill 19-181 responded to this issue in 2019 by delegating regulation of fracking to local jurisdictions (SB 19-181). However, this legislation attempts to solve a statewide issue at a local level and is therefore an inconsistent and insufficient response. For this reason, I urge the Colorado state government to reclaim the authority to regulate fracking and implement a policy to ban all wells within 3000 feet of residential areas and schools, effective 2 years from date of passage. This measure will reduce residents’ exposure to toxic chemicals and their risk of disease while allowing the fracking industry to continue to benefit the Colorado economy and energy sector.

Abstract:
In 2010, twenty-eight bovines on a Pennsylvania beef farm were exposed to a hydraulic fracturing wastewater leak on their grazing pasture. Over the following year, eleven out of seventeen calves born to the exposed animals died. The farmers framed the deaths as outside normal deathly production on the farm, while state institutions claimed the deaths resulted from the farmers’ negligence, framing them as ordinary. I draw on necropolitics to examine how death becomes a normalized mode of capital production in agri-food systems, investigating how the wastewater spill and calves’ deaths ruptured the everyday production of bovine death. The paper argues that death must occur in prescribed sites and at approved times to function as a site of value accumulation in capitalist agriculture. I examine how the spill and calf death events emerged through promiscuous entanglements between overlapping modes of capital extraction across and through the site of the farm. Using assemblages, I trace unruly, promiscuous encounters at this food-energy contact zone to consider how the calves’ deaths render visible the space-time boundaries used to manage more-than-human mortality as a metabolic process in livestock production, and highlight disparate power relations between diverse necropolitical actors and modes of governance.

Abstract:
Flowback/Produced fluid samples were collected from several wells from two Utica/Point Pleasant (UPP) sites (UPPW and UPPS) in Ohio, and one Marcellus (Marcellus Shale Energy and Environment Laboratory (MSEEL)) site in West Virginia over a period of approximately two years. Although these formations have different ages, depositional environments, diagenetic histories, and geochemical and mineralogical compositions (i.e. the UPP is significantly more carbonate rich than the Marcellus which is more siliceous), analysis of trends in fluid species over time shows that, overall, the TDS and major solubilized elements (Na, Ca, Cl) in the UPP and Marcellus brines are remarkably similar. Total dissolved solutes (TDS) in these brines ranged from approximately 40 to 250 g/L salt, and in general, concentrations increased with time elapsed since natural gas well completion and stimulation. The behavior of Na, Br, and Cl suggests that the produced water signatures from these formations are largely derived from the native formational brines which display evidence of originating from evaporated seawater. There is a strong correlation between Cl and Br, indicating that both species behave conservatively, and the similarity among each of these brines suggests no appreciable contribution of salt from halite dissolution because Br is excluded from the halite structure. Cl/Br ratios in the brines range from ~80 to 120 (mg/L/mg/L). Other elements, such as K, which readily reacts between fluids and ion exchange sites on clays, generally exhibit conservative behavior for an individual site, but show significant variations among each of the different well pads. The concentrations of Sr and Ba vary dramatically among well sites, and increase with respect to Cl− over time, suggesting increasing solubilization, presumably from desorption from clay minerals or dissolution of carbonates or sulfates from the source formation(s). The UPPW well site has very low Ba due to high-sulfate input fluid, which resulted in precipitation of barite/celestite in the brines. In contrast the UPPS well site had elevated Sr (~ 3500 mg/L), presumably due to the use of Sr-rich recycled brine used in hydraulic fracturing. The Marcellus site had the highest Ba concentrations (up to 10 g/L) and highest Ba/Sr ratios in the fluids, due to the high concentration of barium in the Marcellus target (~ 1000 ppm, as compared to ~200 ppm in the UPP). These observations suggest that solutes in the FP fluids are derived from native brines, water-rock interactions that have occurred over geologic time scales, as well as some contribution from contemporaneous reactions in the subsurface. The results also show that the composition of the injected fluid can influence flowback fluid chemistry and possibly production efficiency.

Abstract:
Oil and gas (O&G) extraction generates large volumes of produced water (PW) in regions that are often water-stressed. In Wyoming, generators are permitted under the National Pollutant Discharge Elimination System (NPDES) program to discharge O&G PW for beneficial use. In one Wyoming study region, downstream of the NPDES facilities exist naturally occurring wetlands referred to herein as produced water retention ponds (PWRPs). Previously, it was found that dissolved radium (Ra) and organic contaminants are removed within 30 km of the discharges and higher-resolution sampling was required to understand contaminant attenuation mechanisms. In this study, we sampled three NPDES discharge facilities, five PWRPs, and a reference background wetland not impacted by O&G PW disposal. Water samples, grab sediments, sediment cores and vegetation were collected. No inorganic PW constituents were abated through the PWRP series but Ra was shown to accumulate within PWRP grab sediments, upwards of 2721 Bq kg−1, compared to downstream sites. Ra mineral association with depth in the sediment profile is likely controlled by the S cycle under varying microbial communities and redox conditions. Under anoxic conditions, common in wetlands, Ra was available as an exchangeable ion, similar to Ca, Ba and Sr, and S was mostly water-soluble. 226Ra concentration ratios in vegetation samples, normalizing vegetation Ra to sediment Ra, indicated that ratios were highest in sediments containing less exchangeable 226Ra. Sequential leaching data paired with redox potentials suggest that oxic conditions are necessary to contain Ra in recalcitrant sediment minerals and prevent mobility and bioavailability.

Abstract:
Extensive development of horizontal drilling and hydraulic fracturing enhanced energy production but raised concerns about drinking-water quality in areas of shale-gas development. One particularly controversial case that has received significant public and scientific attention involves possible contamination of groundwater in the Trinity Aquifer in Parker County, Texas. Despite extensive work, the origin of natural gas in the Trinity Aquifer within this study area is an ongoing debate. Here, we present a comprehensive geochemical dataset collected across three sampling campaigns along with integration of previously published data. Data include major and trace ions, molecular gas compositions, compound-specific stable isotopes of hydrocarbons (δ13C-CH4, δ13C-C2H6, δ2H-CH4), dissolved inorganic carbon (δ13C-DIC), nitrogen (δ15N-N2), water (δ18O, δ2H, 3H), noble gases (He, Ne, Ar), boron (δ11B) and strontium (87Sr/86Sr) isotopic compositions of water samples from 20 drinking-water wells completed in the Trinity Aquifer. The compendium of data confirms mixing between a deep, naturally occurring salt- (Cl >250 mg/L) and hydrocarbon-rich groundwater with a low-salinity, shallower, and younger groundwater. Hydrocarbon gases display strong evidence for sulfate reduction-paired oxidation, in some cases followed by secondary methanogenesis. A subset of drinking-water wells contains elevated levels of hydrocarbons and depleted atmospherically-derived gas tracers, which is consistent with the introduction of fugitive thermogenic gas. We suggest that gas originating from the intermediate-depth Strawn Group (“Strawn”) is flowing within the annulus of a Barnett Shale gas well, and is subsequently entering the shallow aquifer system. This interpretation is supported by the expansion in the number of affected drinking-water wells during our study period and the persistence of hydrocarbon levels over time. Our data suggest post-genetic secondary water quality changes occur following fugitive gas contamination, including sulfate reduction paired with hydrocarbon oxidation and secondary methanogenesis. Importantly, no evidence for upward migration of brine or natural gas associated with the Barnett Shale was identified.

Abstract:
Oilfield flowback and produced water (FPW) is a waste stream that may offer an alternative source of water for multiple beneficial uses. One practice gaining interest in several semi-arid states is the reuse of FPW for agricultural irrigation. However, it is unknown if the reuse of FPW on edible crops could increase health risks from ingestion of exposed food, or impact crop growth. A greenhouse experiment was conducted using wheat (Triticum aestivum) to investigate the uptake potential of select hydraulic fracturing additives known to be associated with health risks. The selected chemicals included acrylamide, didecyldimethylammonium chloride (DDAC), diethanolamine, and tetramethylammonium chloride (TMAC). Mature wheat grain was extracted and analyzed by liquid chromatography-triple quadrupole mass spectrometry (LC-QQQ) to quantify chemical uptake. Plant development observations were also documented to evaluate impacts of the chemicals on crop yield. Analytical results indicated that TMAC and diethanolamine had significantly higher uptake into both wheat grain and stems than control plants which were not exposed to the four chemicals under investigation. Acrylamide was measured in statistically higher concentrations in the stems only, while DDAC was not detected in grain or stems. Growth impacts included lodging in treated wheat plants due to increased stem height and grain weight, potentially resulting from increased nitrogen application. While analytical results show that uptake of select hydraulic fracturing chemicals in wheat grain and stems is measurable, reuse of FPW for irrigation in real world scenarios would likely result in less uptake because water would be subject to natural degradation, and often treatment and dilution practices. Nonetheless, based on the outstanding data gaps associated with this research topic, chemical specific treatment and regulatory safeguards are still recommended.

Abstract:
The acceleration of climate change necessitates an energy transition in Canada and the United States – one that runs directly counter to the recent explosion of fossil fuel extraction through fracking technology. Is there public support for transition? What are the key predictors? This paper examines public opinion in two neighboring jurisdictions that experienced a hydraulic fracturing boom: Saskatchewan and North Dakota. Survey data is used to describe and compare opinions on fracking, clean energy, and energy transition. We find that compared to people in Saskatchewan, North Dakotans actually see less of a conflict between clean energy and fracking: they are more supportive of both. We examine predictors suggested by previous research, but aim to more carefully separate economic ideology, partisanship, and economic ties to industry. Economic ideology functions as expected, in essentially the same way across jurisdictions. Partisanship is clearly correlated to attitudes towards energy policy in North Dakota, but the relationship is asymmetric by party and issue. The same asymmetry is not true in Saskatchewan. In North Dakota, there is substantial public support for more investment in clean energy, but much less support for energy transition, while in Saskatchewan, the issue is not politicized.

Abstract:
As the largest holder of shale gas resource estimates, China is actively promoting its shale gas development to steer its transitions to a low carbon energy system. The production of shale gas usually needs a large amount of water. According to our estimates, the direct water consumption is about 9700–37600m3/well, and the indirect water consumption is around 32,400–71,100 m3/well. Such a large amount of water consumption could have a serious impact on local human and ecosystem water consumption since China is a country with scarce and unevenly distributed water resources. Water scarcity footprint (WSF) of shale gas production in Chinese provinces is assessed to understand the impacts of shale gas production on local water consumption for other sectors. The results show that the average water pressure for shale gas production in China is higher compared with that of the U.S.. The average WSF in China is 16,574 m3 world. eq/106m3 gas while the WSF in the Barnett shale region in the U.S. is only around 2000 m3 world. eq/106m3 gas. 13 of 31 provinces have even higher WSF than the national average, in which the amount of shale gas resources accounts for about 20% of China's total. Shale gas exploitation in these 13 provinces might not be suitable or must be cautious from the perspective of WSF. The remaining 18 provinces have lower WSFs than the national average. A sustainable way for extracting shale gas in these 18 provinces needs to comprehensively consider WSF, the scale and speed of exploitation and the amount of local shale gas recoverable reserves.

Abstract:
This research presents two new policy-level performance indicators for measuring hydraulic fracturing chemical transparency to address the limitations of existing metrics and provide additional perspectives to stakeholders. Existing indicators do not capture the change in proportions of hydraulic fracturing wells with publicly available chemical information or percent of ingredient mass withheld on chemical disclosure forms. Based on the new indicators, state-level policy changes and the FracFocus register have increased hydraulic fracturing chemical transparency over the past decade and continue to drive measurable improvements. The percent of wells with publicly disclosed ingredients increased from ∼0 to 95% (2010–2019), and the average percent of hydraulic fracturing fluid mass withheld on chemical disclosure forms decreased ∼46.8% (2013–2019). The percent ingredient mass withholding was used to compare the two current regulatory chemical disclosure form approaches (system and traditional). In 2019, the average percent of hydraulic fracturing fluid mass withheld on system approach chemical disclosure forms (0.044%) was 66.3% less than the traditional forms (0.132%). This research improves our capabilities to understand, evaluate, and communicate the effect of chemical transparency policy decisions and corporate practices. Recent lessons learnt from the oil and gas industry should be used to study broader chemical transparency policies, information systems, and communication strategies.

Abstract:
Shale Energy development in the United States has made the community-level impacts of new energy technologies a national concern, resulting in a boom in attention from academics, journalists, and others seeking to learn from the community experiences. A meta-analysis by Walsh et al. (2020) depicts the uneven geographical footprint of research performed in these communities, possibly leading to a phenomenon of research fatigue in communities that have hosted a high number of social science research attempts. In order to better understand and address research fatigue, especially in energy boom communities, we use focus groups and an online-survey of Shale Energy community social scientists to explore the perceived scope, causes, and consequences of and solutions to research fatigue in social research on energy boomtowns. The results show that research fatigue is indeed a major barrier for many researchers in energy impacted communities, but significant geographical variability exists. Furthermore, respondents indicated numerous mitigation strategies to prevent or otherwise reduce research fatigue through better research design and community outreach; however, they also emphasize that real barriers in the nature of scholarly research and the structure of academia prevent the implementation of these strategies. Many of the respondents supported online trainings or forums to inform new energy social science scholars of ways to reduce or mitigate research fatigue and design effective community outreach programs.

Abstract:
Affected by the success of shale gas development in North America, the Chinese government and major oil and gas producers accurately grasped the development trend of shale gas industry, promoted the pilot tests and introduced policies effectively. In 2018, shale gas production in China was 1.53×1010m3. A total of 1000 horizontal wells were drilled. There are some major understanding and innovation achieved, such as stratigraphic division scheme, development characteristics of nanopores, causes of high TOC(Total Organic Carbon) in black shale. The Challenges are discussed. The endowment of shale gas resource is relatively poor. Some key technologies and equipment encounter “bottleneck” and there is poor external environment for development. At last, the paper analyses the development potentials of shale gas in China. The shale gas resources are rich, and shale gas will be the main contributor to the growth of China’s natural gas production. The next step is need to speed up exploration and development, and to increase reserves and production quickly. Also, it is necessary to insist on innovation, offer on-site services, guidance and support, thus providing technical support for realizing new historic leaps of shale gas in China.

Abstract:
A considerable body of academic research has emerged in the last decade identifying many environmental consequences of unconventional hydraulic fracturing (‘fracking’ or ‘UHF’) in the U.K. (for example, on climate change, air pollution, wastewater disposal and water contamination). However, there is much less research on the economic implications of fracking, particularly regarding property values and contributions toward energy security. This article will draw upon primary data collected through twenty semi-structured interviews with key-informants to the fracking industry in the U.K. (including a variety of interviewees from regulatory bodies, academia, the oil and gas industry, and anti-fracking campaigners, giving a reasonable breadth of knowledge, experience and opinion). Qualitative analysis of interview data concludes fracking will contribute only minimally to energy security, whilst having a perceived negative impact for the value of property, particularly those located within close proximity to extraction sites.

Abstract:
Limited air monitoring studies with long-term measurements during all phases of development and production of natural gas and natural gas liquids have been conducted in close proximity to unconventional natural gas well pads.

Abstract:
Hydraulic fracturing or “fracking” is a relatively new method of energy extraction that makes it possible to use considerable amounts of shale gas that were hitherto unreachable. Although proponents of fracking voice their hopes for energy independence and an economic boost, fracking has been under discussion in several countries, its possible risks playing a key role when it comes to political decisions regarding the technology. This paper shall examine media discourses surrounding the usage of fracking with a specific regard to the risks that are constituted. Discourses in the UK, the US and Germany are compared, focusing on similarities and differences. These three countries are chosen since the political approach on fracking has been quite different, with the US being one of the first countries to use fracking. The corpora are analyzed with a focus on the depiction of conflictive issues in the framework of so-called agonality. The public perception of risks is shaped by their dominance in the media and the way they are phrased (e.g. as something to worry about), which means that differences in the depiction of risks between the corpora of these three countries are particularly noteworthy. Most readers will not be experts on fracking and thus rely on linguistic descriptions of the technology and its possible potentials and risks. Thus, it is important to analyze how language constitutes fracking. While all three corpora focus on risks concerning drinking water, there are major differences, e.g. when it comes to the discursive weight of earthquakes that might be caused by fracking. Although this is a risk that could affect all countries, only the UK press describes this as a serious risk. The paper also focuses on risks that are harder to grasp, e.g. threats to the traditional social structure of communities where fracking is practiced.

Abstract:
Background Hundreds of oil wells were drilled along Oil Creek in Pennsylvania in the mid-1800s, birthing the modern oil industry. No longer in operation, many wells are now classified as abandoned, and, due to their age, their locations are either unknown or inaccurately recorded. These historic well sites present environmental, safety, and economic concerns in the form of possible methane leaks and physical hazards. Methods Airborne magnetic and LiDAR surveys were conducted in the Pioneer Run watershed in Oil Creek State Park to find abandoned wells in a historically significant but physically challenging location. Wells were drilled in this area prior to modern geolocation and legal documentation. Although a large number of old wells were abandoned summarily without remediation of the site, much of the land area within Oil Creek State Park is now covered in trees and dense underbrush, which can obscure wellheads. The thick vegetation and steep terrain limited the possibility of ground-based surveys to easily find well sites for methane emissions studies. The data from remote sensing surveys were used to corroborate potential well locations from historic maps and photographs. Potential well sites were verified in a ground-based field survey and monitored for methane emissions. Results Two historic photographs documenting oil activity in the late 1800s were georeferenced using a combination of magnetic and LiDAR data. LiDAR data, which were more useful in georeferencing and in field verification, identified 290 field locations in the Pioneer Run watershed, 86% of which were possible well sites. Sixty-two percent of the ground-verified wells remained unplugged and comprised the majority of leaking wells. The mean methane emissions factor for unplugged wells was 0.027 ± 0.099 kg/day, lower than other Appalachian Basin methane emissions estimates. Conclusions LiDAR was used for the first time, in combination with an airborne magnetic survey, to reveal underground oil industry features and inform well identification and remediation efforts in difficult-to-navigate regions. In the oldest oil fields, where well casing has been removed or wood conductor casing was installed, historic photographs provide additional lines of evidence for oil wells where ground disturbances have concealed surface features. Identification of well sites is necessary for mitigation efforts, as unplugged wells emit methane, a potent greenhouse gas.

Abstract:
Background Whereas it is plausible that unconventional natural gas development (UNGD) may adversely affect cardiovascular health, little is currently known. We investigate whether UNGD is associated with acute myocardial infarction (AMI). Methods In this observational study leveraging the natural experiment generated by New York’s ban on hydraulic fracturing, we analyzed the relationship between age- and sex-specific county-level AMI hospitalization and mortality rates and three UNGD drilling measures. This longitudinal panel analysis compares Pennsylvania and New York counties on the Marcellus Shale observed over 2005-2014 (N=2,840 county-year-quarters). Results A hundred cumulative wells is associated with 0.26 more hospitalizations per 10,000 males 45-54y.o. (95% CI 0.07,0.46), 0.40 more hospitalizations per 10,000 males 65-74y.o. (95% CI 0.09,0.71), 0.47 more hospitalizations per 10,000 females 65-74y.o. (95% CI 0.18,0.77) and 1.11 more hospitalizations per 10,000 females 75y.o.+ (95% CI 0.39,1.82), translating into 1.4-2.8% increases. One additional well per square mile is associated with 2.63 more hospitalizations per 10,000 males 45-54y.o. (95% CI 0.67,4.59) and 9.7 hospitalizations per 10,000 females 75y.o.+ (95% CI 1.92,17.42), 25.8% and 24.2% increases respectively. As for mortality rates, a hundred cumulative wells is associated with an increase of 0.09 deaths per 10,000 males 45-54y.o. (95% CI 0.02,0.16), a 5.3% increase. Conclusions Cumulative UNGD is associated with increased AMI hospitalization rates among middle-aged men, older men and older women as well as with increased AMI mortality among middle-aged men. Our findings lend support for increased awareness about cardiovascular risks of UNGD and scaled-up AMI prevention as well as suggest that bans on hydraulic fracturing can be protective for public health.

Abstract:
The large-scale extraction of unconventional resources from shale reservoirs utilizing horizontal hydraulic fracturing has significantly improved economic development in U.S. However, the increased well production has been accompanied by rising concerns about potential impact resulting from excessive freshwater usage and wastewater generation. Currently, water issues have become increasingly challenging with the development of shale reservoirs. In this paper, technical, economic, and environmental challenges encountered during energy production are reviewed with a focus on water issues due to hydraulic fracturing in the U.S. Moreover, the detailed discussion of characteristics and contaminant sources of wastewater indicates the wastewater composition is complicated and varies over time and location. Understanding these factors contributed to high contaminant levels of wastewaters is important to grow awareness of the impacts of hydraulic fracturing on water quality for both operators and the public. Furthermore, pertinent wastewater management strategies for different purposes are highlighted. Although there is no one-size-fits-all solution, understanding the advantages and limitations of different treatment methods is critical for decision-makers to develop appropriate management system. The aim behind this review is to provide a reference for selecting better and practical solutions for current wastewater issues and identifying key issues for future research.

Abstract:
Unconventional formations have been actively developed in the US since 2008. However, it is challenging to quantify the impact of technological advancement and geology on production. In addition, the economics of unconventionals is not well-understood. In this paper, we studied five major unconventional formations in the US: the Bakken, Eagleford, Haynesville, Marcellus, and Wolfcamp formations. We used historical data to quantify the impact of technological and geological variations on production. To accomplish this, we identified four phases of unconventional development over the past 12 years during which drilling and completion technology, initial investment, and commodity prices were similar: Phases 1–4. Using statistical analysis, we compared well performance of each phase. Then, we generated type curves for each phase for economic studies. Initial analysis shows that between January 2008 and December 2019, 60,611 horizontal wells were completed in these formations, producing about 8.185 billion barrels of oil, 90 trillion cubic feet of gas, and generating an estimated $816 billion in gross revenue. For the statistical analysis, the level of uncertainty ($${P}_{10}/{P}_{90}$$P10/P90ratio) reduced from Phase 1 to Phase 4 across all formations, suggesting consistent improvements in well productivity over time while county-level analysis shows spatial disparity in well performance. We infer that technology drives temporal changes while geology drives spatial differences in well performance. From economic analysis, Phase 4 type wells had the best production performance, partly, due to improved drilling and completion efficiency. It was also because operators targeted their best acreage to maximize their asset’s potential.

Abstract:
Natural gas, the largest source for electricity generation in the US, is produced via hydraulic fracturing. Fracturing uses water mixed with chemical additives to free natural gas from the shale formation. While downhole, these fluids contact small formation particles produced during well-perforation and remain in contact with the particles until the fluids return to the well surface. We performed experiments to investigate the physical and chemical interactions between Marcellus shale particles and fluid at high temperature (80oC). The treatments in this study include incubating shale particles in solutions containing individual organic and inorganic additives used during fracturing (hydrochloric acid, persulfate, LEB-10X, WGA, FRS, Revert Flow (RF), and BXL). The particles exhibited a measurable influence on flowback fluid chemistry when treated with chemical additives. An optimized methodology was developed for laser-based Particle Size Analysis (PSA) with a wet-dispersion unit that was then used to measure changes in particle size after treatment. The PSA results indicate that mixing speeds >2800 rpm can cause particle breakage and low speeds are required for PSA of shales. We observed no difference in particle size across treatments after incubation, indicating that clay swelling likely occurs during incubation. The influence of contact time was investigated for the inorganic treatments (persulfate and HCl containing treatments) given that these treatments resulted in higher concentrations of element release and precipitation compared to the organics additives tested. The results show that contact time is an essential consideration in shale transformation studies. Our findings link changing water chemistry to specific fracturing additives and provide key information for understanding the fluid-rock interactions.

Abstract:
We investigated the endorsement of an expanded construct of environmental justice (ExEJ) that includes the rights of nature, other species, and future generations. We contextualized this study in terms of the environmental challenges posed by hydraulic fracturing. We used structural equation modeling to test a model that hypothesized that attitudes toward fracking would mediate an endorsement of ExEJ. We tested multiple factors that research suggests contribute to those attitudes using a student and non-student sample from a state experiencing fracking activity. Results suggest that self-transcendent factors directly predicted ExEJ endorsement, while self-focus factors predicted positive attitudes toward fracking, and a varied set of factors predicted a negative fracking attitude. Attitudes had no direct effect on ExEJ. Patterns of result suggest self-transcendent factors and avenues for change facilitate ExEJ, while self-enhancement factors influence positive fracking attitudes. Interpretations of these patterns are offered.

Abstract:

Abstract:
Due to advances in unconventional extraction techniques, the rate of fossil fuel production in the United States (US) is higher than ever before. The disposal of waste gas via intentional combustion (flaring) from unconventional oil and gas (UOG) development has also been on the rise, and may expose nearby residents to toxic air pollutants, light pollution and noise. However, little data exists on the extent of flaring in the US or the number of people living near UOG flaring activity. Utilizing nightly sattelite observations of flaring from the Visible Infrared Imaging Radiometer Suite Nightfire product, 2010 Census data and a dataset of remotely sensed building footprints, we applied a dasymetric mapping approach to estimate the number of nightly flare events across all oil shale plays in the contiguous US between March 2012 and February 2020 and characterize the populations residing within 3 km, 5 km and 10 km of UOG flares in terms of age, race and ethnicity. We found that three basins accounted for over 83% of all UOG flaring activity in the contiguous US over the 8 year study period. We estimated that over half a million people in these basins reside within 5 km of a flare, and 39% of them lived near more than 100 nightly flares. Black, indigenous, and people of color were disproportionately exposed to flaring.

Abstract:
This research assessed the efficacy of UV and UV advanced oxidation processes (UV/AOPs) to reduce dissolved organic carbon (DOC), total petroleum hydrocarbons (TPH), and microorganisms in hydraulic fracturing produced water. To improve water quality conditions before UV treatment with and without added hydrogen peroxide (UV/H2O2), produced water was treated with coagulation, flocculation, and sedimentation (CFS) and biologically activated carbon filtration (BACF). BACF was more effective than CFS as a pre-UV and UV/AOP treatment strategy and reduced DOC, TPH, and absorbing species by over 70% which, subsequently, resulted in the highest hydroxyl radical steady-state concentrations during UV and UV/H2O2 experiments. UV alone minimally degraded DOC, while UV/H2O2 improved DOC and TPH degradation by 9% to 36%. Interestingly, UV without added H2O2 created an in situ AOP by generating hydroxyl radicals with similar steady-state concentrations to that of UV/H2O2. UV was found to be highly effective for the inactivation of microorganisms that were cultured in produced water by reducing microbial communities dominated by Citrobacter by 4 logs after only 30 mJ/cm2. Together, these results demonstrate UV/AOP as a potential strategy to not only improve the treatment and reuse of produced water but also reduce biocide use in fracturing fluids.

Abstract:
This paper explores the socio-economic legacy created by an extractive industry as it developed, or sought to develop, in nine different communities or regions across Australia, Canada, the United States, and Wales – drawing on mixed-method research collected between 2011 and 2018. By the early 2010s, a number of unconventional fossil fuel companies were securing land access agreements for seismic and drilling exploration in the Western Downs region of South-East Queensland, the Northern Rivers region of North-Eastern New South Wales, the states of New York and Pennsylvania, the Province of New Brunswick, and southern Wales. Stark cultural, social and environmental contrasts between communities within each nation shaped community responses to potential industry development – levels of social license for developments, community responses and subsequent unconventional fossil fuel development varied widely. This article explores the impact of the industry on community resilience. A resilient community is likely to have high social capital, including strong social networks, feelings of safety and trust, sense of belonging, diversity, citizen power and participation. These social responses to the industry, combined with the existing local contexts and the differing regulatory frameworks of each community/region, can be argued to have led to divergent effects on overall community social and economic resilience across our case studies. Power, industrial impacts, relationships, resources, social action, timing of the debates, equity concerns, and strategic decision making (or lack thereof) shaped the degree of resilience with which each community/region responded. In four of our cases, resilience declined (e.g., due to increased economic homogenisation, decreasing social connectivity and citizen power); in five cases resilience increased (e.g., the legacy created by the emergence of social movements substantially increased social connectivity, sense of belonging and citizen power).

Abstract:
Few studies have examined the land use, fragmentation, and conversion impacts from siting unconventional oil and gas wells on farmland. This exploratory GIS study examined these issues in the Bakken shale region in North Dakota. A total of 3,577 well pads containing 6,201 wells located on farmland were digitized and examined in this study. The findings indicate that in addition to land used for agricultural purposes (such as cropland and rangeland), other land types such as native woodlands and wetlands have also been converted to well pads and associated infrastructure. The single-well and multi-well pad footprints in this study were higher than the industrial estimates. The overall average well pad footprint is 6.45 acres while the average single-well pad and multi-well pad footprint is 5.26 acres and 8.60 acres, respectively. Eighty two percent of well pads had 1-2 wells sited on them. The findings show that the well pad footprint differed based on whether the well pad was located in a core or periphery county, on rangeland or cropland, and that single-well well pad footprint increased over time. Several issues that require further research are outlined.

Abstract:
In hydraulic fracturing fluids, the oxidant persulfate is used to generate sulfate radical to break down polymer-based gels. However, sulfate radical may be scavenged by high concentrations of halides in hydraulic fracturing fluids, producing halogen radicals (e.g., Cl•, Cl2•–, Br•, Br2•–, and BrCl•–). In this study, we investigated how halogen radicals alter the mechanisms and kinetics of the degradation of organic chemicals in hydraulic fracturing fluids. Using a radical scavenger (i.e., isopropanol), we determined that halogenated products of additives such as cinnamaldehyde (i.e., α-chlorocinnamaldehyde and α-bromocinnamaldehyde) and citrate (i.e., trihalomethanes) were generated via a pathway involving halogen radicals. We next investigated the impact of halogen radicals on cinnamaldehyde degradation rates. The conversion of sulfate radicals to halogen radicals may result in selective degradation of organic compounds. Surprisingly, we found that the addition of halides to convert sulfate radicals to halogen radicals did not result in selective degradation of cinnamaldehyde over other compounds (i.e., benzoate and guar), which may challenge the application of radical selectivity experiments to more complex molecules. Overall, we find that halogen radicals, known to react in advanced oxidative treatment and sunlight photochemistry, also contribute to the unintended degradation and halogenation of additives in hydraulic fracturing fluids.

Abstract:
This review focuses on recent developments in electrochemical technology (with special emphasis on electrocoagulation, electro-oxidation, and electro-Fenton) to treat petroleum industry effluents (offshore and hydraulic fracturing extraction, as well as refinery effluents). In addition, an overview is given of what these processes face to position themselves as consolidated technologies.

Abstract:
Carboxymethyl cellulose (CMC) is a polymer used in many different industrial sectors. In the oil and gas industry, CMC is often used during hydraulic fracturing (fracking) operations as a thickening agent for effective proppant delivery. Accumulations of CMC at fracture faces (known as filter cakes) can impede oil and gas recovery. Although chemical oxidizers are added to disrupt these accumulations, there is industrial interest in developing alternative, enzyme-based treatments. Little is known about CMC biodegradation under fracking conditions. Here, we enriched a methanogenic CMC-degrading culture and demonstrated its ability to enzymatically utilize CMC under the conditions that typify oil fields. Using the extracellular enzyme fraction from the culture, significant CMC viscosity reduction was observed between 50 and 80˚C, at salinities up to 20% (w/v) and at pH 5-8 compared to controls. Similar levels of viscosity reduction by extracellular enzymes were observed under oxic and anoxic conditions. This proof-of-concept study demonstrates that enzyme biotechnology holds great promise as a viable approach to treating CMC filter cakes under oilfield conditions.

Abstract:
Hydraulic fracturing of unconventional hydrocarbon resources involves the sequential injection of a high-pressure, particle-laden fluid with varying pH’s to make commercial production viable in low permeability rocks. This process both requires and produces extraordinary volumes of water. The water used for hydraulic fracturing is typically fresh, whereas “flowback” water is typically saline with a variety of additives which complicate safe disposal. As production operations continue to expand, there is an increasing interest in treating and reusing this high-salinity produced water for further fracturing. Here we review the relevant transport and geochemical properties of shales, and critically analyze the impact of water chemistry (including produced water) on these properties. We discuss five major geochemical mechanisms that are prominently involved in the temporal and spatial evolution of fractures during the stimulation and production phase: shale softening, mineral dissolution, mineral precipitation, fines migration, and wettability alteration. A higher salinity fluid creates both benefits and complications in controlling these mechanisms. For example, higher salinity fluid inhibits clay dispersion, but simultaneously requires more additives to achieve appropriate viscosity for proppant emplacement. In total this review highlights the nuances of enhanced hydrogeochemical shale stimulation in relation to the choice of fracturing fluid chemistry.

Abstract:
Youth perspectives on energy interventions are rarely sought or acted on in local and national policy, despite the stake young people have in the future created by today’s energy and environmental policies. The debate on unconventional shale gas development (hydraulic fracturing, or ‘fracking’) is one context in which decisions taken today have long-term, intergenerational consequences, with environmental justice intersecting with energy needs. This study investigated young people’s perceptions and experiences of exploratory fracking and associated political processes in order to understand their experiences of environmental justice. In depth, qualitative field research was conducted with 84 young people in locations within 20 miles (32 kilometers) of operational exploratory fracking sites prior to the moratorium in England announced in November 2019. Data were analysed with attention to recognition, participation and distributional justice. Young people experienced environmental, democratic and social injustices through lack of recognition of their aims and values as both youth and members of a rural community, and exclusion from formal participation in decision-making. Young people saw economic and thus environmental power residing with industry closely tied to national government, and experienced a tension between desire to trust institutional authority and betrayal by these same institutions. We argue that this case study of young people in ‘the sacrifice zone’ demonstrates a connection between depoliticisation and anti-politics, and that these processes undermine trust in democracy. There is a need for recognition and meaningful inclusion of young people and local communities in decision-making, particularly where the consequences of the decisions last for generations.

Abstract:
Shale gas is a relatively clean-burning fossil fuel, produced by hydraulic fracturing. This technology may be harmful to the environment; therefore, environmentally friendly methods to extract shale gas have attracted considerable attention from researchers. Unlike previous studies, this study is a comprehensive investigation that uses systematic analyses and detailed field data. The environmental challenges associated with shale gas extraction, as well as measures to mitigate environmental impacts from the source to end point are detailed, using data and experience from China’s shale gas production sites. Environmental concerns are among the biggest challenges in practice, mainly including seasonal water shortages, requisition of primary farmland, leakage of drilling fluid and infiltration of flowback fluid, oil-based drill cuttings getting buried underground, and induced seismicity. China’s shale gas companies have attempted to improve methods, as well as invent new materials and devices to implement cleaner processes for the sake of protecting the environment. Through more than 10-year summary, China’s clean production model for shale gas focuses on source pollution prevention, process control, and end treatment, which yield significant results in terms of resource as well as environmental protection, and can have practical implications for shale gas production in other countries, that can be duplicated elsewhere.

Abstract:
Hydraulic fracturing or ‘fracking’ overlays a major industrial operation on the land in areas where shale and tight hydrocarbon resources can be exploited. Every aspect of the fracking operation can cause environmental damage, although the damage from any individual well is both unlikely and usually fairly limited. Such damage has been extensively documented, giving the impression that fracking activity is bad for the environment. There is no yes or no answer to the question ‘Is fracking harmful to the environment’; rather, it is an issue that must be resolved politically rather than scientifically.

Abstract:
The presence of methane and other hydrocarbons in domestic-use groundwater aquifers poses significant environmental and human health concerns. Isotopic measurements are often relied upon as indicators of groundwater aquifer contamination with methane. While these parameters are used to infer microbial metabolisms, there is growing evidence that isotopes present an incomplete picture of subsurface microbial processes. This study examined the relationships between microbiology and chemistry in groundwater wells located in the Denver-Julesburg Basin of Colorado, a rapidly urbanizing area with active oil and gas development. A primary goal was to determine if microbial data can reliably indicate the quantities and sources of groundwater methane. Comprehensive chemical and molecular analyses were performed on 39 groundwater well samples from five aquifers. Elevated methane concentrations were found in only one aquifer, and both isotopic and microbial data support a microbial origin. Microbial parameters had similar explanatory power as chemical parameters for predicting sample methane concentrations. Furthermore, a subset of samples with unique microbiology corresponded with unique chemical signatures that may be useful indicators of methane gas migration, potentially from nearby coal seams interacting with the aquifer. Microbial data may allow for more accurate determination of groundwater contamination and improved long-term water quality monitoring compared solely to isotopic and chemical data in areas with microbial methane.

Abstract:
Abandoned oil and gas wells are one of the most uncertain sources of methane emissions into the atmosphere. To reduce these uncertainties and improve emission estimates, we geospatially and statistically analyze 598 direct methane emission measurements from abandoned oil and gas wells and aggregate well counts from regional databases for the United States (U.S.) and Canada. We estimate the number of abandoned wells to be at least 4,000,000 wells for the U.S. and at least 370,000 for Canada. Methane emission factors range from 1.8 × 10–3 g/h to 48 g/h per well depending on the plugging status, well type, and region, with the overall average at 6.0 g/h. We find that annual methane emissions from abandoned wells are underestimated by 150% in Canada and by 20% in the U.S. Even with the inclusion of two to three times more measurement data than used in current inventory estimates, we find that abandoned wells remain the most uncertain methane source in the U.S. and become the most uncertain source in Canada. Understanding methane emissions from abandoned oil and gas wells can provide critical insights into broader environmental impacts of abandoned wells, which are rapidly growing in number around the world.