Repository for Oil and Gas Energy Research (ROGER)

Abstract:
Climate change, the imbalance between China's domestic energy supply and demand, and the success of the shale gas revolution in the United States have been the main motivators for China to actively issue shale gas development policies and explore its own path on this industry. This paper estimates three indicators of economic development: regional GDP, employment level, and the housing price index by using data from China's largest shale gas region, the Fuling District in Chongqing (a municipality in China). The analysis uses a Synthetic Control Method (SCM) model based on data from Fuling itself and other 34 counties of the Chongqing municipality over the period from 2005 to 2018. The results demonstrate that shale gas development has a significant positive effect on both regional GDP and employment level, with average impact growth rates respectively of 9.8% and 12.0%. By contrast, we find an insignificant effect of shale gas development on housing prices. These results support the case for further development of shale gas in China. Note that in some areas our results differ from existing literature, providing a reference for further research in this area.

Abstract:
The high management cost of wastewater generated during oil and gas production using hydraulic fracturing technology necessitates economically viable alternative technologies for remediation and reuse. In this study, an Oklahoma native microalgae strain, Komvophoron sp., was grown in four different flowback and produced water samples generated during hydraulic fracturing. Biomass production profile and pollutant removal efficiency of the strain were evaluated. The experimental data demonstrated that this strain was able to grow in all wastewater samples examined when suitable light intensity and CO2 flow rate were provided. Biomass productivity of the strain varied from 5.5 to 12 g m−3 day−1 depending on the wastewater sample used in the cultivation experiments. Very high nitrogen and phosphorus removal from the growth medium, up to 99 and 63%, respectively, could be achieved by growing and harvesting algal biomass in the wastewater samples. A mathematical model developed based on pH, light intensity and CO2 enriched air flow rate as system variables well described the experimental biomass productivity and pollutant removal efficiency data. The proposed mathematical model was successfully used to identify sets of operating conditions which would maximize biomass productivity and macronutrient removal efficiencies. Hence, the model developed in this study is a useful tool to assess technical viability and design of an efficient algal wastewater remediation process to reduce the impact of hydraulic fracturing on environment while producing biomass that can be converted to industrial bio-products including biofuels.

Abstract:
The effectiveness of oil and gas produced water (OGPW) applied to unpaved roads to reduce particulate matter (PM10) generation has not been well-characterized. Here we quantify the efficacy of OGPW compared to commercial and alternative byproducts as dust suppressants applied to unpaved roads and estimate efficacy of a dust suppressant extrapolated from both lab experiments and published data for OGPW across U.S. states. Both treated and untreated OGPW, simulated brines, and commercial dust suppressants were characterized by major and trace element composition and then applied to road aggregate in the laboratory. PM10 generation after treatment was quantified, both before and after simulated rain events to assess the need for multiple applications. We found the dust suppression efficacy of all OGPW to be less than commercial products and alternative byproducts such as waste soybean oil. In addition, OGPW lost efficacy following simulated rain events, which would require repeated applications of OGPW to maintain dust suppression. The dust suppression efficacy of OGPW can be estimated based on two chemical measurements, the sodium absorption ratio (SAR) and the total dissolved solids (TDS). OGPW with the lowest SAR and highest TDS performed best as dust suppressants while high SAR and lower TDS led to greater dust generation.

Abstract:
Our study goal was to investigate the impact of biocides and nanoparticles (NPs) on the microbial diversity in a hydraulic fracturing impacted stream. Biocides and NPs are known for their antimicrobial properties and controlling microbial growth. Previous work has shown that biocides can alter the microbial community composition of stream water and may select for biocide-resistant bacteria. Additional studies have shown that nanoparticles can also alter microbial community composition. However, previous work has often focused on the response to a single compound. Here we provide a more thorough analysis of the microbial community response to three different biocides and three different nanoparticles. A microcosm-based study was undertaken that exposed stream microbial communities to either biocides or NPs. Our results showed a decrease in bacterial abundance with different types of nanoparticles, but an increase in microbial abundance in biocide-amended treatments. The microbial community composition (MCC) was distinct from the controls in all biocide and NP treatments, which resulted in differentially enriched taxa in the treatments compared to the controls. Our results indicate that NPs slightly altered the MCC compared to the biocide-treated microcosms. After 14 days, the MCC in the nanoparticle-treated conditions was similar to the MCC in the control. Conversely, the MCC in the biocide-treated microcosms was distinct from the controls at day 14 and distinct from all conditions at day 0. This finding may point to the use of NPs as an alternative to biocides in some settings.

Abstract:
Background:  Prenatal exposure to hydraulic fracturing (HF), a chemically intensive oil and gas extraction method, may be associated with adverse birth outcomes, but no health studies have been conducted in California. Methods:  We conducted a retrospective cohort study of 979,961 births to mothers in eight California counties with HF between 2006 and 2015. Exposed individuals had at least 1 well hydraulically fractured within 1 km of their residence during pregnancy; the reference population had no wells within 1 km, but at least one oil/gas well within 10 km. We examined associations between HF and low birth weight (LBW), preterm birth (PTB), small for gestational age birth (SGA), and term birth weight (tBW) using generalized estimating equations and assessing urban-rural effect modification in stratified models. Results:  Fewer than 1% of mothers (N = 1,192) were exposed to HF during pregnancy. Among rural mothers, HF exposure was associated with increased odds of LBW (odds ratio [OR] = 1.74; 95% confidence interval [CI] = 1.10, 2.75), SGA (OR = 1.68; 95% CI = 1.42, 2.27) and PTB (OR = 1.17; 95% CI = 0.64, 2.12), and lower tBW (mean difference: –73 g; 95% CI = –131, –15). Among urban mothers, HF exposure was positively associated with SGA (OR = 1.23; 95% CI = 0.98, 1.55), inversely associated with LBW (OR = 0.83; 95% CI = 0.63, 1.07) and PTB (OR = 0.65; 95% CI = 0.48, 0.87), and not associated with tBW (mean difference: –2 g; 95% CI = –35, 31). Conclusion:  HF proximity was associated with adverse birth outcomes, particularly among rural Californians.

Abstract:
Low-cost gravity-driven membrane (GDM) filtration has the potential to efficiently manage highly decentralized shale gas wastewater (SGW). In this work, the feasibility of combining low dosage pre-ozonation with the GDM process was evaluated in the treatment of SGW. The results showed that pre-ozonation significantly increased the stable flux (372%) of GDM filtration, while slightly deteriorating the quality of the effluent water in terms of organic content (−14%). These results were mainly attributed to the conversion of macromolecular organics to low-molecular weight fractions by pre-ozonation. Interestingly, pre-ozonation markedly increased the flux (198%) in the first month of operation also for a GDM process added with granular activated carbon (GGDM). Nevertheless, the flux of O3-GGDM systems dropped sharply around the 25th day of operation, which might be due to the rapid accumulation of pollutants in the high flux stage and the formation of a dense fouling layer. Pre-ozonation remarkably influenced the microbial community structure. And O3-GDM systems were characterized by distinct core microorganisms, which might degrade specific organics in SGW. Furthermore, O3-GDM outperformed simple GDM as a pretreatment for RO. These findings can provide valuable references for combining oxidation technologies with the GDM process in treating refractory wastewater.

Abstract:
Pressure-retarded osmosis (PRO) is a promising membrane technology for harnessing the osmotic energy of saline solutions. PRO is typically considered with seawater/river water pairings however greater energy can be recovered from hypersaline solutions including produced water (PW) from the petroleum industry. One of the major challenges facing the utilization of hypersaline PW is its high fouling propensity on membranes. In this unique experimental evaluation, real PW from different sites was pretreated to varying degrees: i) minimal, ii) intermediate, and iii) extensive. The treated effluent was subsequently used for PRO testing and fouling rates were assessed for different membrane configurations over multiple cycles. Commercial grade flat sheet (FLS) coupons and novel hollow fiber (HF) modules were compared to validate the lower fouling propensity of HF membranes in PRO application. When minimally pretreated PW (10-micron cartridge filtration (CF)) was tested in FLS mode, severe membrane fouling occurred and the PRO flux decreased by 60%. In contrast, HF modules showed <1% flux decrease under both minimal and intermediate pretreatment schemes. Extensive pretreatment (1-micron CF, dissolved air flotation (DAF), powdered activated carbon, and microfiltration) reduced FLS PRO flux decline to <1%. These results confirm that PW can be treated to suitable levels for PRO application to avoid membrane fouling. Further validation of these pretreatment methods requires long term pilot testing and techno-economic assessment.

Abstract:
There is public and scientific concern about air, soil and water contamination and possible adverse environmental and human health effects as a result of hydraulic fracturing activities. The use of greener chemicals in fracturing fluid aims to mitigate these effects. This study compares fracturing fluids marketed as either ‘conventional’ or ‘green’, as assessed by their chemical composition and their toxicity in bioassays. Chemical composition was analysed via non-target screening using liquid chromatography - high resolution mass spectrometry, while toxicity was evaluated by the Ames fluctuation test to assess mutagenicity and CALUX reporter gene assays to determine specific toxicity. Overall, the results do not indicate that the ‘green’ fluids are less harmful than the ‘conventional’ ones. First, there is no clear indication that the selected green fluids contain chemicals present at lower concentrations than the selected conventional fluids. Second, the predicted environmental fate of the identified compounds does not seem to be clearly distinct between the ‘green’ and ‘conventional’ fluids, based on the available data for the top five chemicals based on signal intensity that were tentatively identified. Furthermore, Ames fluctuation test results indicate that the green fluids have a similar genotoxic potential than the conventional fluids. Results of the CALUX reporter gene assays add to the evidence that there is no clear difference between the green and conventional fluids. These results do not support the claim that currently available and tested green-labeled fracturing fluids are environmentally more friendly alternatives to conventional fracturing fluids.

Abstract:
Research on hydraulic fracturing has documented disruptive effects on communities, noting parallels with and departures from previous energy “boomtown” studies. Some recent national and regional-scale research utilizes proximity to energy industry activity as a predictor of public opinion and perceived impacts of hydraulic fracturing, but few studies examine the role of proximity at the local scale. The current study focuses on two Pennsylvania communities that experienced a heavy wave of Marcellus Shale development, testing whether proximity to different levels of industry activity predicts the degree of support for and perception of impacts from hydraulic fracturing. Also examined is the effect of perceived exposure to industry activity. The results of this study show that proximity to hydraulic fracturing activity matters, reducing support for hydraulic fracturing and strengthening views of community and environmental impacts. This effect of proximity is, however, indirect, operating through respondents’ perceived exposure to the array of hydraulic fracturing activities that took place in their areas.

Abstract:
For shale gas resevoirs development, many researches focus on how to improve the estimated ultimate recovery (EUR), and ignore the relation of economic benefits and EUR. Therefore, based on the research of EUR evaluation procedure as the basis of economic estimation, the relation of economic benefits and EUR is revealed in detail, and the economy-geology-engineering (EGE) model is creatively built. The results show that six researched wells all have economic benefits: the average EUR is 1.60 × 108 m3, and the after-tax averages of net present value, financial internal rate of return and investment payback period (Pt) are 434.32 × 104 USD, 10.39% and 4.45 years respectively. Combining with the seepage theory and on-site experience, the negative relation of Pt and development degree of free gas is determined. The economic benefits for the unit volume of shale gas are close about 0.03 USD/m3 under the current development technologies. The influence degrees of economic parameters from large to small are gas price, drilling cost, fracturing cost, business cost and subsidy respectively. The proposed EGE model can effectively predict the economic benefits with the complex geology-engineering factors in the Changning block, and the corresponding method can be generalized to more fields.

Abstract:
To date, little research has investigated how public perceptions of policies to ban or restrict fossil-fuel extraction change over time; yet this topic is of crucial importance as countries worldwide seek to transition towards ‘net zero’ economies. This study addresses this gap by focusing on public responses to the 2019 moratorium on shale gas extraction in England, using an analytical framework comprising awareness, interpretations and opinions, and a mixed-method approach combining national survey, social media and local case interviews. Findings show high levels of awareness and support for the moratorium, yet differences between coalitions of interest based on ideology, scale and demographics. Social media analyses reveal a peak in public response across several days during a general election campaign in which different parties took divergent positions on shale gas. Public support for the moratorium – and induced seismicity as the primary reason for its introduction - was evidenced by the national survey, yet coincided with scepticism about its timing, extent and motivation, as indicated by social media activity and local case interviews. For some publics, the moratorium was a ploy to ensure electoral support, embedded in public distrust. This study indicates the merits of a mixed-method approach to understand the psychological and institutional context of public responses to policy change as it unfolds over time, and discusses the longer term implications of politicised attitudes for energy transitions.

Abstract:
Water scarcity is one of the main challenges worldwide that might propose various engineering and economic issues. Petroleum industries have encountered these issues seriously, which required pretreatment facilities before reinjecting the produced water into the production wells. To assure that the treated water has no side effect on the environment, the treatment processes would perform three times by the photo-Fenton flotation method. This paper, it is aimed to calculate the treated water, required water, and saving water for chemically enhanced oil recovery methods (CEOR), hydraulic fracturing (HF), and other service facilities for completion and drilling performances. According to the results of this study, oil-well#3 has the highest water savings among all the wells with the 89% of daily water-saving, and oil-well#4 has the highest water savings among oil wells with the 75% of daily water saving. Consequently, in Sirri oilfield, the water-saving percentage is about 82% and 72%, which indicated that it is required 18%, 28% of the total water volume for implantation of HF process and CEOR methods, respectively. The total annual required water for this oilfield is 4131 MM m3/Day.

Abstract:
The chemical characteristic of flowback fluid from hydraulic fracturing for shale gas exploration/production in various localizations is presented. The results of statistical analysis have shown that variability in the chemical composition of these fluids is statistically significant and depends on the time difference between fracturing process and flowback sampling as well as sampling spot within the installation for flowback collection. Parameters which depend on sampling schedule (time and spot of sampling) are as follows: electrical conductivity and concentration of ammonia, boron, barium, calcium, lithium, sodium, magnesium, manganese, sodium, strontium, silicate, bromide, and chloride. Independent parameters are pH, total organic carbon (TOC), concentration of potassium, and iron. The ranges of the values of the characteristic parameters were determined, taking into account the representativeness of the samples, supported by statistical tests. The methods for the reuse of flowback fluids in terms of chemical composition are presented.

Abstract:
Background: There is growing concern about the recent increase in oil and gas development using hydraulic fracturing. Studies linking adverse birth outcomes and maternal proximity to hydraulic fracturing wells exist but tend to use individualized maternal and infant data contained in protected health care records. In this study, we extended the findings of these past studies to evaluate if analogous effects detected with individualized data could be detected from non-individualized county-wide aggregated data.Design and Methods: This study used a retrospective cohort of 252,502 birth records from 1999 to 2019 gathered from a subset sample of 5 counties in the state of Colorado where hydraulic fracturing activities were conducted. We used Generalized Linear Models to evaluate the effect of county-wide well density and production data over unidentified birth weight, and prematurity data. Covariates used in the model were county-wide statistics sourced from the US Census.Results: Our modeling approach showed an interesting effect where hydraulic fracturing exposure metrics have a mixed effect directional response. This effect was detected on birth weight when well density, production and their interaction are accounted for. The interaction effect provides an additional interpretation to discrepancies reported previously in the literature. Our approach only detected a positive association to prematurity with increased production.Conclusions: Our findings demonstrate two main points: First, the effect of hydraulic fracturing is detectable by using county-wide unidentified data. Second, the effect of hydraulic fracturing can be complicated by the number of operations and the intensity of the activities in the area.

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In many countries, natural gas is perceived more favorably than other fossil fuels. Here, we experimentally test (N = 2931) how perceptions of natural gas vary depending on what it is called. We find that Americans have stronger positive feelings for the term “natural gas” than “natural methane gas” (d = 0.59), “fossil gas” (d = 0.80), “fracked gas” (d = 0.81), “methane” (d = 0.94), and “methane gas” (d = 0.96). Democrats and Republicans both reported more positive views of “natural gas” than “natural methane gas” or “methane [gas].” But the patterns for the two political parties differed for perceptions of “fossil gas” and “fracked gas,” which were both viewed relatively positively by Republicans but negatively by Democrats. Analyses of open-ended word associations found that many participants associated methane with words like “pollution” and “global warming,” whereas they associated natural gas with words like “clean.” The results suggest that the terms used for this fossil fuel have very different meanings among the public, which may affect people's risk perceptions, consumer choices, and support for related policies.

Abstract:
Drawing from hazard and disaster literature, this article advances Freudenburg’s concept of recreancy and Hobfoll’s Conservation of Resources theory in response to calls for more theory development in research on hydraulic fracturing. Respectively, these theoretical frames refer to stress associated with trust in institutional failure to safeguard the wellbeing of society, as well as resource loss, threat of loss, or investment of resources without return or gain. We contribute to the expanding body of knowledge in energy and social science research by investigating risk perceptions of induced seismicity (earthquakes) associated with hydraulic fracturing processes. Using structural equation modeling, we analyze data from a 2018 household telephone survey in two regions of Oklahoma (N = 600). Findings indicate that perceptions of recreancy (β = 0.38), opinion of fracking risks (β = 0.31), and number of earthquakes (β = 0.11) directly affect perceptions of earthquake risk, while political views, economic resource loss and views of fracking benefits are indirectly related to perceptions of earthquake risk.

Abstract:
Background Northeastern British Columbia (Canada) is an area of unconventional natural gas (UNG) exploitation by hydraulic fracturing, which can release several contaminants, including volatile organic compounds (VOCs). To evaluate gestational exposure to contaminants in this region, we undertook the Exposures in the Peace River Valley (EXPERIVA) study. Objectives We aimed to: 1) measure VOCs in residential indoor air and tap water from EXPERIVA participants; 2) compare concentrations with those in the general population and explore differences related to sociodemographic and housing characteristics; and 3) determine associations between VOC concentrations and density/proximity to UNG wells. Methods Eighty-five pregnant women participated. Passive air samplers were analyzed for 47 VOCs, and tap water samples were analyzed for 44 VOCs. VOC concentrations were compared with those from the Canadian Health Measure Survey (CHMS). We assessed the association between different metrics of well density/proximity and indoor air and tap water VOC concentrations using multiple linear regression. Results 40 VOCs were detected in >50% of air samples, whereas only 4 VOCs were detected in >50% of water samples. We observed indoor air concentrations >95th percentile of CHMS in 10–60% of samples for several compounds (acetone, 2-methyl-2-propanol, chloroform, 1,4-dioxane, hexanal, m/p-xylene, o-xylene, styrene, decamethylcyclopentasiloxane, dodecane and decanal). Indoor air levels of chloroform and tap water levels of total trihalomethanes were higher in Indigenous participants compared to non-Indigenous participants. Indoor air levels of chloroform and acetone, and tap water levels of total trihalomethanes were positively associated with UNG wells density and proximity metrics. Indoor air BTEX (benzene, toluene, ethylbenzene, xylenes) levels were positively correlated with well density/proximity metrics. Conclusion Our results suggest higher exposure to certain VOCs in pregnant women living in an area of intense unconventional natural gas exploitation compared with the general Canadian population, and that well density/proximity is associated with increased exposure to certain VOCs.

Abstract:
Public response to energy projects affects the emergence of new technologies and the distribution of their risks and benefits. Here we use thousands of individually authored comments submitted during a regulatory review of unconventional shale gas development in New York State to reconcile previous, inconsistent results about the relationship between proximity and opposition to energy projects. We find that members of the public opposed unconventional shale gas development for different reasons, which varied systematically with proximity to unconventional gas wells. Public discourse in proximate communities was diverse, invoking environmental, social, economic and political impacts, and was anchored by concerns specific to a particular place. By contrast, a few nationally salient environmental concerns dominated public discourse in communities farther from development. Our results demonstrate that public response reflects the mobilization of alternative constituencies with unique understandings of the issue. Distinguishing among these is critical for understanding the nature of public response.

Abstract:
Both unconventional and conventional oil and gas production have led to instances of brine contamination of near-surface environments from spills of saline produced waters. Strontium isotope ratios (87Sr/86Sr) have been used as a sensitive tracer of sources of brine contamination in surface waters and shallow aquifers in areas where oil and gas production are limited to only a few reservoirs and produced water sources are well-defined. Recent expansion of conventional and unconventional oil and gas production to additional tight formations within sedimentary basins has resulted in production of formation waters from multiple oil and gas reservoirs that may have similar chemical and isotopic ratios, including 87Sr/86Sr. This study evaluates the utility of 87Sr/86Sr, the most widely available tracer dataset beyond major ion chemistry and water stable isotopes, as a tracer of brine contamination related to conventional and unconventional oil and gas production in the Williston, Appalachian and Permian basins. Multiple stacked oil and gas reservoirs within each basin have overlapping formation water 87Sr/86Sr, based on a non-parametric statistical test. For example, in the Appalachian Basin, produced waters from unconventional gas production in the Middle Devonian Marcellus and Upper Ordovician Utica shales have overlapping 87Sr/86Sr. In the Permian Basin, produced waters from the unconventional Pennsylvanian-Permian Wolfcamp Shale and conventional and unconventional Pennsylvanian Cisco/Canyon/Strawn formations have similar 87Sr/86Sr. In the Williston Basin produced waters from Late Devonian to Early Mississippian Bakken Formation unconventional oil production have overlapping 87Sr/86Sr with produced waters associated with minor production of conventional oil from the Middle Devonian Winnipegosis. Improved spatial characterization of 87Sr/86Sr and other isotopic signatures of produced waters from various oil/gas reservoirs are needed to constrain geographic and depth variability of produced waters in hydrocarbon producing regions. This is particularly important, as unconventional oil and gas production expands in areas of existing conventional oil and gas production, where delineating sources of saline produced waters in cases of accidental surface spills or subsurface leakage will become a greater challenge. Sr isotopes alone may not be able to distinguish produced waters in areas with overlapping production from reservoirs with similar isotopic signatures.

Abstract:
Lightly salted surface waters Hydraulic fracturing uses a water-based mixture to open up tight oil and gas formations. The process is mostly contained, but concerns remain about the potential for surface water contamination. Bonetti et al. found a small increase in certain ions associated with hydraulic fracturing across several locations in the United States (see the Perspective by Hill and Ma). These small increases appeared 90 to 180 days after new wells were put in and suggest some surface water contamination. The magnitude appears small but may require that more attention be paid to monitoring near-well surface waters. Science, aaz2185, this issue p. 896; see also abk3433, p. 853 The impact of unconventional oil and gas development on water quality is a major environmental concern. We built a large geocoded database that combines surface water measurements with horizontally drilled wells stimulated by hydraulic fracturing (HF) for several shales to examine whether temporal and spatial well variation is associated with anomalous salt concentrations in United States watersheds. We analyzed four ions that could indicate water impact from unconventional development. We found very small concentration increases associated with new HF wells for barium, chloride, and strontium but not bromide. All ions showed larger, but still small-in-magnitude, increases 91 to 180 days after well spudding. Our estimates were most pronounced for wells with larger amounts of produced water, wells located over high-salinity formations, and wells closer and likely upstream from water monitors. A small but detectable increase in salt concentration associated with hydraulic fracturing appears in surface waters. A small but detectable increase in salt concentration associated with hydraulic fracturing appears in surface waters.

Abstract:
Tapping into oil and gas reserves comes at the expense of contaminating water Tapping into oil and gas reserves comes at the expense of contaminating water

Abstract:
In many basins across the United States, oil and gas (O&G) wastewater high in alkaline earth metals (such as Ba, Sr, and Ca) and radioactivity is discharged to surface waters. Freshwater mussels have experienced high mortality rates downstream of O&G discharges despite significant dilution. 87Sr/86Sr and Sr/Ca measured in mussel soft tissue could prove to be an inexpensive, efficient biomonitoring tool if tissue concentrations show O&G produced water signatures similar to those of shells. O&G-derived 226Ra/228Ra has not previously been studied in freshwater mussels. Additionally, accumulation of O&G-derived metals in mussel tissue may impact bioaccumulation in higher-trophic level organisms. A tank study using freshwater mussels (Elliptio complanata) was completed using Marcellus Shale-produced water diluted with regional surface water to realistic dilution levels (100–600-fold dilution). Results from the three-month study suggest Sr/Ca and 87Sr/86Sr robustly trace O&G pollution in mussel soft tissue. The high-dose tank soft tissue average 87Sr/86Sr [0.709502 ± (7.68 × 10–5)] was significantly more radiogenic than average control tank soft tissue [0.706808 ± (4.23 × 10–5)]. Radium concentrations in soft tissue were not significantly different between tanks. Changes in the soft tissue chemistry of mussel species from relatively low doses of O&G wastewater suggest surface water disposal volumes may require re-evaluation to prevent further impacts.

Abstract:
Appropriate produced water (PW) management is critical for oil and gas industry. Understanding PW quantity and quality trends for one well or all similar wells in one region would significantly assist operators, regulators, and water treatment/disposal companies in optimizing PW management. In this research, historical PW quantity and quality data in the New Mexico portion (NM) of the Permian Basin from 1995 to 2019 was collected, pre-processed, and analyzed to understand the distribution, trend, and characteristics of PW production for potential beneficial use. Various machine learning algorithms were applied to predict PW quantity for different types of oil and gas wells. Both linear and non-linear regression approaches were used to conduct the analysis. The prediction results from five-fold cross-validation showed that the Random Forest Regression model reported high prediction accuracy. The AutoRegressive Integrated Moving Average model showed good results for predicting PW volume in time series. The water quality analysis results showed that the PW samples from the Delaware and Artesia Formations (mostly from conventional wells) had the highest and the lowest average total dissolved solids concentrations of 194,535 mg/L and 100,036 mg/L, respectively. This study is the first research that comprehensively analyzed and predicted PW quantity and quality in the NM-Permian Basin. The results can be used to develop a geospatial metrics analysis or facilitate system modeling to identify the potential opportunities and challenges of PW management alternatives within and outside oil and gas industry. The machine learning techniques developed in this study are generic and can be applied to other basins to predict PW quantity and quality.

Abstract:
Following the large increase in unconventional hydrocarbon production in North America and elsewhere in the last 15 years, many jurisdictions have implemented groundwater monitoring programs to verify whether these subsurface industrial activities impact shallow groundwater quality. The interpretation of groundwater monitoring results typically relies mostly on dissolved alkane chemical and isotopic composition to infer the potential presence of thermogenic hydrocarbons presumed to originate from a deep source, which may indicate contamination. However, ambiguous results are frequently obtained, and post-genetic processes are often suspected to have modified the original gas composition. Here, we present a systematic approach to identify alkane origin with greater certainty, by thoroughly investigating four processes that may affect dissolved hydrocarbon gas: 1) late-stage methanogenesis, 2) oxidation (of methane or higher alkanes), 3) mixing between different gas sources, and 4) secondary methanogenesis. This is achieved by using empirical equations and fractionation factors available in the literature, combined to site-specific isotopic tracers (δ13CCH4, δ2HCH4, δ2HH2O, δ13CDIC) in groundwater samples. This approach is being tested and applied to a study area located in southern New Brunswick, Canada. The area overlies the McCully gas field from which unconventional natural gas is produced since 2003, and the nearby Elgin area, a prospective area for condensates. Results demonstrate that the presence of methane in groundwater is not related to the proximity of gas wells. In a few shallow wells located very close to producing gas wells in the McCully gas field, methane and ethane were detected, and the compositional and isotopic data sometimes seemed to point towards a thermogenic origin. However, consideration of the four processes led to the conclusion that the gas was of microbial origin, and that it had been oxidized to various levels. In contrast, thermogenic gas was detected in groundwater in the Elgin area, where no commercial production has yet taken place. In this area the natural hydrocarbon gas context is more complex, and the gas from some of the wells was affected by mixing, oxidation, and late-stage methanogenesis. Finally, the approach used in this paper has proven capable of disentangling the original isotopic signature from post-genetic modifications and, despite initial ambiguity, has shown no evidence that past hydraulic fracturing in the McCully gas field has affected shallow groundwater quality.

Abstract:
Oil shale has received attention as an alternative energy source to petroleum because of its abundant reserves. Exploitation of oil shale can be divided into two types: ex situ and in situ exploitation. In situ transformation has been favoured because of its various advantages. Heating of oil shale leads to the production of oil and gas. To explore the influence of solid residue after pyrolysis of oil shale on the groundwater environment, we performed ultrapure water–rock interaction experiments. The results showed that Pb tended to accumulate in solid residues during pyrolysis. Additionally, the Pb concentration goes up in the immersion solution over time and as the pyrolysis temperature increased. In contrast, when we measured the soaking data of benzene series, the concentrations of benzene and toluene produced at temperatures over 350 ℃ were highest in the four oil shale pyrolysis samples after pyrolysis. The water–rock interaction experiment for 30 days led to benzene and toluene concentrations that were 104 and 1070-fold over the limit of China’s standards for groundwater quality. Over time, the content of benzene series was attenuated via biological actions. The results show that in situ oil shale mining can lead to continuous pollution in the groundwater environment.

Abstract:
Methane (CH4) emissions from oil and natural gas (O&NG) systems are an important contributor to greenhouse gas emissions. In the United States, recent synthesis studies of field measurements of CH4 emissions at different spatial scales are ~1.5–2× greater compared to official greenhouse gas inventory (GHGI) estimates, with the production-segment as the dominant contributor to this divergence. Based on an updated synthesis of measurements from component-level field studies, we develop a new inventory-based model for CH4 emissions, for the production-segment only, that agrees within error with recent syntheses of site-level field studies and allows for isolation of equipment-level contributions. We find that unintentional emissions from liquid storage tanks and other equipment leaks are the largest contributors to divergence with the GHGI. If our proposed method were adopted in the United States and other jurisdictions, inventory estimates could better guide CH4 mitigation policy priorities.

Abstract:
High volume hydraulic fracturing (HVHF) is a contentious issue worldwide. It is a crucial policy issue due to its significant impact on multiple stakeholders and, as a result, requires extensive public consultation and exposure. One process deployed in some liberal democracies to address this controversy is forming an independent expert review panel to receive public submissions and then prepare a report for policymakers. Our paper investigated how closely the review panel reports reflect and weigh the public submissions and to explore the subjects in which there is agreement or disagreement across the various reports. This study used the Leximancer automated text analysis software to compare key themes in the sub-national reports and public submissions. We find a consistent pattern across jurisdictions of public submissions reflecting health and environment while official reports focus on industry and economic development. There is a wide range of congruency between the jurisdictions on the capacity of the expert reports to reflect public opinion. Following from this divergence, we aim to contribute to more meaningful discussions regarding effective communication strategies between the government and the public to ensure review panel reports fairly represent public concerns.

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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.

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The potential contamination of shallow groundwater with inorganic constituents is a major environmental concern associated with shale gas extraction through hydraulic fracturing. However, the impact of shale gas development on groundwater quality is a highly controversial issue. The only way to reliably assess whether groundwater quality has been impacted by shale gas development is to collect pre-development baseline data against which subsequent changes in groundwater quality can be compared. The objective of this paper is to provide a conceptual and methodological framework for establishing a baseline of inorganic groundwater quality in shale gas areas, which is becoming standard practice as a prerequisite for evaluating shale gas development impacts on shallow aquifers. For this purpose, this paper first reviews the potential sources of inorganic contaminants in shallow groundwater from shale gas areas. Then, it reviews the previous baseline studies of groundwater geochemistry in shale gas areas, showing that a comprehensive baseline assessment includes documenting the natural sources of salinity, potential geogenic contamination, and potential anthropogenic influences from legacy contamination and surface land use activities that are not related to shale gas development. Based on this knowledge, best practices are identified in terms of baseline sampling, selection of inorganic baseline parameters, and definition of threshold levels.

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We present an updated fuel-based oil and gas (FOG) inventory with estimates of nitrogen oxide (NOx) emissions from oil and natural gas production in the contiguous US (CONUS). We compare the FOG inventory with aircraft-derived (“top-down”) emissions for NOx over footprints that account for ∼25% of US oil and natural gas production. Across CONUS, we find that the bottom-up FOG inventory combined with other anthropogenic emissions is on average within ∼10% of top-down aircraft-derived NOx emissions. We also find good agreement in the trends of NOx from drilling- and production-phase activities, as inferred by satellites and in the bottom-up inventory. Leveraging tracer−tracer relationships derived from aircraft observations, methane (CH4) and non-methane volatile organic compound (NMVOC) emissions have been added to the inventory. Our total CONUS emission estimates for 2015 of oil and natural gas are 0.45 ± 0.14 Tg NOx/yr, 15.2 ± 3.0 Tg CH4/yr, and 5.7 ± 1.7 Tg NMVOC/yr. Compared to the US National Emissions Inventory and Greenhouse Gas Inventory, FOG NOx emissions are ∼40% lower, while inferred CH4 and NMVOC emissions are up to a factor of ∼2 higher. This suggests that NMVOC/NOx emissions from oil and gas basins are ∼3 times higher than current estimates and will likely affect how air quality models represent ozone formation downwind of oil and gas fields.

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Current approaches relating thermogenic gases to either shale source rocks (predominantly type II kerogen) or coal source rocks (predominantly type III kerogen) are not reliable and not globally applicable. This is because these mostly empirical approaches were developed using small poorly-constrained datasets from limited locations. The evaluation of a large global dataset of molecular and isotopic properties of gases from unconventional shale and coal reservoirs suggests that two genetic diagrams based on stable carbon isotopes of methane and ethane, δ13C-C2H6 versus δ13C-CH4 and δ13C-CH4 versus Δ(δ13C-C2H6 - δ13C-CH4), provide the best separation of shale-sourced and coal-sourced gases. Newly designated genetic fields and shale/coal separation lines on these diagrams were tested and validated using data from five petroleum systems with, likely, only shale (class B and A organofacies) source rocks (the Maracaibo Basin in Venezuela, the Guajira Basin in Colombia and the Rub Al Khali Basin in Iran) and only coal (class F organofacies) source rocks (the Southern Permian Basin in Germany and the Sichuan Basin in China). The practical usefulness of this new approach to gas-source correlations was demonstrated in two case studies from petroleum systems with debated source rock organofacies (the Mozambique Basin in Mozambique and the Indus Basin in Pakistan). These better constrained and more reliable diagrams with genetic fields and shale/coal separation lines represent a new tool for the evaluation of petroleum systems.

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Conflict characterizes energy projects across Canada and around the world. While claims about economics, the environment and Indigenous rights dominate headlines, energy conflicts also feature struggles over the construction of space and scale. Building on work in energy geographies, this paper compares the spatial politics of three contested fossil fuel projects, focusing on how antagonistic parties frame issues to advance their positions, in turn shaping perceptions of scale. Drawing on reports, media coverage, and other secondary sources, we examine: the Trans Mountain pipeline in Western Canada; the Coastal GasLink pipeline in Wet’suwet’en territory, British Columbia; and shale gas drilling in New Brunswick. The analysis reveals how actors construct space and scale to persuade, build alliances, and exclude people or issues from consideration. Project proponents generally ‘scale up’ claims about benefits and ‘scale down’ impacts, while opponents do the opposite – even as both strategically engage with governance at multiple scales. We argue that taking spatial politics seriously can reveal power dynamics in competing representations of space, improve transparency in energy project evaluations by unveiling tacit proponent strategies, and reveal biases in impact assessment and legal processes when their mandates favour the spatial strategies of project proponents.

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Tracing produced water origins from wells hydraulically fractured with freshwater-based fluids is sometimes predicated on assumptions that (1) each geological formation contains compositionally unique brine and (2) produced water from recently hydraulically fractured wells resembles fresher meteoric water more so than produced water from older wells. These assumptions are not valid in Williston Basin oil wells sampled in this study. Although distinct average 228Ra/226Ra ratios were found in water produced from the Bakken and Three Forks Formations, average δ2H, δ18O, specific gravity, and conductivity were similar but exhibited significant variability across five oil fields within each formation. Furthermore, initial produced water (“flowback”) was operationally defined based on the presence of glycol ether compounds and water from wells that had produced <56% of the amount of fluids injected and sampled within 160 days of fracturing. Flowback unexpectedly exhibited higher temperature, specific gravity, conductivity, δ2H, and δ18O, but lower oxidation–reduction potential and δ11B, relative to the wells thought to be producing formation brines (from wells with a produced-to-injected water ratio [PIWR] > 0.84 and sampled more than 316 days after fracturing). As such, establishing an overall geochemical and isotopic signature of produced water compositions based solely on chemical similarity to meteoric water and formation without the consideration of well treatments, well completion depth, or lateral location across the basin could be misleading if these signatures are assumed to be applicable across the entire basin. These findings have implications for using produced water compositions to understand the interbasin fluid flow and trace sources of hydraulic fracturing fluids.

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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.

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Introduction Natural gas compressor stations are located throughout the country and are used to maintain gas flow and ensure continuous distribution through the pipeline network. Compressor stations emit many air contaminants including volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). While the serious health effects associated with the inhalation of elevated pollutant levels are clear, the relationship between proximity to natural gas compressor stations and residential health effects is not well understood. Community members living near a natural gas compressor station in Eastern Ohio expressed concerns regarding their air quality; therefore, the objective of this study was to assess exposure to airborne organics in residential air near the compressor station. Methods Our team conducted a 24-hour air sampling campaign to assess outdoor and indoor air contaminant levels at 4 homes near the Williams Salem Compressor Station in Jefferson County, Ohio. Air quality was assessed using two techniques: 1) summa canisters to quantify VOC concentrations and 2) passive air samplers to evaluate a broader panel of VOCs and SVOCs. Results Among the three homes situated < 2 km from the compressor station, indoor benzene levels were 2-17 times greater than the Ohio Environmental Protection Agency (EPA) indoor standard due to vapor intrusion. Multiple other VOCs, including ethylbenzene, 1,2,4-trimethylbenzene, 1,2 dichloroethane, 1,3 butadiene, chloroform, and naphthalene also exceeded state standards for indoor concentrations. Several SVOCs were also detected inside and outside participants’ homes, including benzene and naphthalene derivatives. Conclusion Our results validate the community members’ concerns and necessitate a more comprehensive epidemiological investigation into the exposures associated with natural gas compressor stations and methods to mitigate elevated exposures. Alarming levels of VOCS were detected inside of homes. Further research is needed to determine the source of VOC exposure and potential health effects.

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Oil and gas development has led to environmental hazards and community concerns, particularly in relation to water supply issues. Filing complaints with state agencies enables citizens to register concerns and seek investigations. We evaluated associations between county-level socio-economic and demographic factors, oil and gas drilling, and three outcomes in Pennsylvania between 2004 and 2016: number of oil and gas complaints filed, and both the number and proportion of state investigations of water supply complaints yielding a confirmed water supply impairment (i.e., “positive determination”). We used hierarchical Bayesian Poisson and binomial regression analyses. From 2004 to 2016, 9,404 oil and gas-related complaints were filed, of which 4,099 were water supply complaints. Of those, 3,906 received investigations, and 215 yielded positive determinations. We observed a 47% increase in complaints filed per $10,000 increase in annual median household income (MHI) (Rate Ratio [RR]: 1.47, 95% credible interval [CI]: 1.09–1.96) and an 18% increase per 1% increase in educational attainment (RR: 1.18, 95% CI: 1.11–1.26). While the number of complaints filed did not vary by race/ethnicity, the odds of a complaint yielding a positive determination were 0.81 times lower in counties with a higher proportion of marginalized populations (Odds Ratio [OR]: 0.81 per 1% increase in percent Black, Asian, and Native American populations combined, 95% CI: 0.64–0.99). The odds of positive determinations were also lower in areas with higher income (OR per $10,000 increase in MHI: 0.35, 95% CI: 0.09–0.96). Our results suggest these relationships are complex and may indicate potential environmental and procedural inequities, warranting further investigation.

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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.

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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.

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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.

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Understanding methane emissions from the natural gas supply chain continues to be of interest. Previous studies identified that measurements are skewed due to “super-emitters”, and recently, researchers identified temporal variability as another contributor to discrepancies among studies. We focused on the latter by performing 17 methane audits at a single production site over 4 years, from 2016 to 2020. Source detection was similar to Method 21 but augmented with accurate methane mass rate quantification. Audit results varied from ∼78 g/h to over 43 kg/h with a mean emissions rate of 4.2 kg/h and a geometric mean of 821 g/h. Such high variability sheds light that even quarterly measurement programs will likely yield highly variable results. Total emissions were typically dominated by those from the produced water storage tank. Of 213 sources quantified, a single tank measurement represented 60% of the cumulative emission rate. Measurements were separated into four categories: wellheads (n = 78), tank (n = 17), enclosed gas process units (n = 31), and others (n = 97). Each subgroup of measurements was skewed and fat-tailed, with the skewness ranging from 2.4 to 5.7 and kurtosis values ranging from 6.5 to 33.7. Analyses found no significant correlations between methane emissions and temperature, whole gas production, or water production. Since measurement results were highly variable and daily production values were known, we completed a Monte Carlo analysis to estimate average throughput-normalized methane emissions which yielded an estimate of 0.093 ± 0.013%.

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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.

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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.

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Unconventional petroleum development involving large volume fluid injection into horizontal well bores, referred to as hydraulic fracturing (HF, or fracking), began in the Montney Trend of northeast British Columbia, Canada, in 2005, quickly initiating earthquakes. Earthquake frequency increased substantially in the Montney by 2008, in relation to the number of wells fracked and the volume of injected frack water. A spatiotemporal filter was used to associate earthquakes with HF wells. A total of 439 earthquakes (M 1.0 - 4.6 (NRCAN catalogue) during 2013-2019 have close association with HF activity, of which 77% are associated with three operators. Fifteen percent of HF wells in the Montney are associated with these earthquakes, while 1.7% of HF wells are associated with M ≥ 3.0 earthquakes. There are strong linear relationships between the maximum earthquake magnitude each year and the annual volume of injected frack fluid. M ≥ 3.0 earthquakes are associated with large cumulative frack water volumes for antecedent time periods of 1 - 3 years, often with fluid injection by multiple operators. Eighty-seven percent of the Montney M ≥ 3.0 earthquakes have associated HF triggering events, but a few are sufficiently distant to be ambiguous. Distances from the induced earthquake epicentres indicate a variety of causal mechanisms are involved. It is concluded that ~60% - 70% of M ≥ 3.0 earthquakes are induced by hydraulic fracturing. HF-induced earthquakes can be considered in part related to the cumulative development density from multiple proximal operators and cumulative antecedent fluid injection over periods ranging from a few months to a few years. It is probable that induced earthquakes of M > 5 will occur in the future. There are significant public safety and infrastructure risks associated with future HF-induced earthquakes in the Peace River area. To carry out HF operations effectively and safely, potentially destructive earthquakes must be avoided or mitigated. The Traffic Light Protocol mitigation system used in British Columbia appears unlikely to prevent large magnitude earthquakes. Risk avoidance therefore becomes important and could include the establishment of frack-free zones proximal to populations and critical infrastructure.

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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.

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Anthropogenic activities can lead to the loss, fragmentation, and alteration of wildlife habitats. I reviewed the recent literature (2014–2019) focused on the responses of avian, mammalian, and herpetofaunal species to oil and natural gas development, a widespread and still-expanding land use worldwide. My primary goals were to identify any generalities in species’ responses to development and summarize remaining gaps in knowledge. To do so, I evaluated the directionality of a wide variety of responses in relation to taxon, location, development type, development metric, habitat type, and spatiotemporal aspects.

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Environmental and public health risks related to onshore unconventional oil and gas development (OUOGD) continue to be at the center of public concerns and policy discussions. Our work fills a research gap by critically reviewing the feasibility of applying systemic causation models to assess environmental and public health risks associated with OUOGD and provides a catalyst for future research. Our primary objectives are to further the conceptual OUOGD process model and increase stakeholder awareness of useful systemic risk assessment tools for deliberating, communicating, and managing potential hazards. After examining popular linear and systemic risk assessment methods, benefits, and limitations, we critically assess the value of systemic techniques in OUOGD. A three-level process model (field development, pad-well, and well-phase) is synthesized from incomplete models found in the literature. The Systems-Theoretic Accident Model and Process (STAMP) is applied to elucidate a general risk control structure from diverse and multi-disciplinary references. Using this abstraction, we highlight the importance of leveraging systemic analysis approaches for environmental and public health risk management in OUOGD. The increasing significance of these methods given the adoption of new digital technology (e.g., drones, robotics, big data analytics, artificial intelligence, internet of things) to decision-making is evident. We recommend that researchers and practitioners (i.e., companies and regulators) thoughtfully embrace systemic risk analyses in their work to enhance the associated body of knowledge for understanding and preventing OUOGD accidents with potential impacts on public health and the environment.

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Abstract. Methane emissions associated with the production, transport, and use of oil and natural gas increase the climatic impacts of energy use; however, little is known about how emissions vary temporally and with commodity prices. We present airborne and ground-based data, supported by satellite observations, to measure weekly to monthly changes in total methane emissions in the United States' Permian Basin during a period of volatile oil prices associated with the COVID-19 pandemic. As oil prices declined from ∼ USD 60 to USD 20 per barrel, emissions changed concurrently from 3.3 % to 1.9 % of natural gas production; as prices partially recovered, emissions increased back to near initial values. Concurrently, total oil and natural gas production only declined by ∼ 10 % from the peak values seen in the months prior to the crash. Activity data indicate that a rapid decline in well development and subsequent effects on associated gas flaring and midstream infrastructure throughput are the likely drivers of temporary emission reductions. Our results, along with past satellite observations, suggest that under more typical price conditions, the Permian Basin is in a state of overcapacity in which rapidly growing associated gas production exceeds midstream capacity and leads to high methane emissions.