Repository for Oil and Gas Energy Research (ROGER)

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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.

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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.

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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.

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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

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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.

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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.

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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.

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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.

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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.

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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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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.

Abstract:
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.

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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.

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Objectives To evaluate the long-term (psychosomatic) health consequences of man-made earthquakes compared with a non-exposure control group. Exposure was hypothesised to have an increasingly negative impact on health outcomes over time. Setting Large-scale gas extraction in the Netherlands causing earthquakes and considerable damage. Participants A representative sample of inhabitants randomly selected from municipal population records; contacted 5 times during 21 months (T1: N=3934; T5: N=2150; mean age: 56.54; 50% men; at T5, N=846 (39.3%) had no, 459 (21.3%) once and 736 (34.2%) repeated damages). Main measures (Psychosomatic) health outcomes: self-rated health and Mental Health Inventory (both: validated; Short Form Health Survey); stress related health symptoms (shortened version of previously validated symptoms list). Independent variable: exposure to the consequences of earthquakes assessed via physical (peak ground acceleration) and personal exposure (damage to housing: none, once, repeated). Results Exposure to induced earthquakes has negative health consequences especially for those whose homes were damaged repeatedly. Compared with a no-damage control group, repeated damage was associated with lower self-rated health (OR:1.64), mental health (OR:1.83) and more stress-related health symptoms (OR:2.52). Effects increased over time: in terms of relative risk, by T5, those whose homes had repeated damage were respectively 1.60 and 2.11 times more likely to report poor health and negative mental health and 2.84 times more at risk of elevated stress related health symptoms. Results for physical exposure were comparable. Conclusion This is the first study to provide evidence that induced earthquakes can have negative health consequences for inhabitants over time. It identifies the subpopulation particularly at risk: people with repeated damages who have experienced many earthquakes. Findings can have important implications for the prevention of negative health consequences of induced earthquakes.

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In the last decade, unconventional oil and gas (UOG) has changed the world’s energy landscapes, often outpacing governments’ efforts to regulate it. Yet, few studies focus on the processes of governance, particularly on questions of procedural equity. Here we examine the process of the 2014 Colorado Oil and Gas Task Force (TF), which was established to address regulatory conflicts over drilling, particularly along the Northern Colorado Front Range. The TF aimed to create a level playing field for influencing decision-making. However, we find that several power mechanisms were deployed by the state and the industry, ensuring that those with the least opportunity to meaningfully influence outcomes were also most likely to be impacted by the TF’s regulatory recommendations had the least opportunity to meaningfully influence the process and its outcomes. Thus we advance existing literature on procedural injustice by focusing on the underlying power mechanisms that help structure procedural injustice in these processes.

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As oil production in the Permian Basin surges, the impact of shale production on groundwater resources has become a growing concern. Most existing studies focus on the impact of shale production on shallow freshwater aquifers. There is little understanding of the shale development’s impact on other groundwater resources (e.g., deep carbonate aquifers and deep basin meteoric aquifers). The possible natural hydraulic connections between shallow aquifers and formation water suggest such an impact can be consequential. This study explores the relationship between shale production and groundwater using produced water (PW) samples from active unconventional oil wells. Focusing on the most productive portion of the Permian Basin—the four-county region in Southeast New Mexico between 2007 and 2016, a large produced water dataset allows us to analyze the conditional correlations between shale oil production and PW constituents. The results suggest that (1) expanding from primarily conventional wells to unconventional wells during the recent shale boom has led to dramatic increases of the TDS, chloride, sodium, and calcium levels in groundwater (i.e., producing formation). (2) Nearby oil well density positively correlates with the TDS, chloride, and sodium levels in the PW samples.

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Varying the stop lights Traffic light protocols can help to mitigate induced earthquakes from unconventional oil production. However, they are not geographically tuned to account for how shaking may actually translate to structural damage. Schultz et al. incorporated damage tolerance into a traffic light protocol for the Eagle Ford shale play. They found that shut-off may be necessary more quickly in populated regions, whereas sparsely populated areas of the play can take up to a magnitude 5 earthquake without issue. This risk-based strategy provides a more nuanced approach to regulating induced seismicity. Science, this issue p. 504 Risks from induced earthquakes are a growing concern that needs effective management. For hydraulic fracturing of the Eagle Ford shale in southern Texas, we developed a risk-informed strategy for choosing red-light thresholds that require immediate well shut-in. We used a combination of datasets to simulate spatially heterogeneous nuisance and damage impacts. Simulated impacts are greater in the northeast of the play and smaller in the southwest. This heterogeneity is driven by concentrations of population density. Spatially varying red-light thresholds normalized on these impacts [moment magnitude (Mw) 2.0 to 5.0] are fairer and safer than a single threshold applied over a broad area. Sensitivity tests indicate that the forecast maximum magnitude is the most influential parameter. Our method provides a guideline for traffic light protocols and managing induced seismicity risks. Accounting for risk provides a more nuanced traffic light protocol for regulating induced seismicity. Accounting for risk provides a more nuanced traffic light protocol for regulating induced seismicity.

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Methane emission estimates for oil and gas production sites, based on observations lasting seconds to minutes, are becoming more common, but interpreting the emission estimates is challenging. Short-term observations made at the same sites, within days of one another, can lead to very different emission estimates. Using two independent sets of short duration measurements made at a group of 33 dry-gas production sites, this work demonstrates that sets of short duration measurements can be reconciled if distributions of emissions at multiple sites, rather than measurements at individual sites, are compared. This work also demonstrates that short duration measurements made at the equipment level can be extrapolated to longer term emission estimates for individual sites using models that account for intermittency in emissions. This approach can predict expected ranges of emissions for additional sites and can be used to identify site level observations that are outside of predicted ranges, which indicate potential abnormal emissions.

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Orphaned oil and gas wells are abandoned wells for which the cost of environmental impacts usually falls on governments and the general public. Government agencies responsible for well plugging often face funding shortfalls and many orphaned wells remain unplugged. To address this and support the oil and natural gas industry, federal governments are already spending, or considering spending, billions of dollars to plug orphaned oil and gas wells. Here, we analyze oil and gas data for the United States and Canada and identify policy recommendations that can best address environmental impacts of abandoned and orphaned wells. At least 116,245 wells across 32 states and four Canadian provinces/territories are operated by companies filing for bankruptcy in the first half of 2020, which may be an indication that many wells will be orphaned in the near future. Moreover, there are 4,700,000 historic and active oil and gas wells in the United States and another 790,000 in Canada. Of these, 2,000,000 and 310,000 wells are active in the United States and Canada, respectively. Thus, three of five wells ever drilled in the United States are currently inactive (2,700,000 wells), but only one in three are plugged (1,500,000 wells). Plugging involves isolating zones containing oil, gas, and water and is the main strategy for well abandonment. If the orphaned well stimulus funding comes through, tens of thousands of wells will be plugged within a few years. Well plugging at this scale far exceeds current rates of plugging, and it is important that we work to ensure long-term environmental benefits of well abandonment to water, air, climate, ecosystems, and human health. Minimizing environmental impacts of the millions of abandoned and orphaned wells in the United States, Canada, and abroad will allow for an economically beneficial and environmentally safe transition to a carbon-neutral economy.

Abstract:
In 2012 Pennsylvania's legislature increased the unconventional natural gas (UNG) well-to-building setback requirement from 200 ft to 500 ft through Act 13. To evaluate this policy, we identified all setback incident locations where a UNG well was within 500 ft of a building both before and after the implementation of Act 13. Using an interrupted time series design, we found that Act 13 did not significantly alter how wells were sited in relation to nearby buildings. Of the 1042 wells that contained a building within 500 ft – equating to ~10.1% of UNG wells (n = 11,148) and ~14.7% well pads (n = 479) – a total of 371 well setback incidents occurred after Act 13, likely due from the existing well pad exemption (35%) and a combination of landowner consent and regulatory variances rather than encroaching building construction. Overall, our study suggests that exemptions are an important and underappreciated aspect of oil and gas well setback rulemaking and highlights the relevance of other health-protective regulatory tools often promulgated alongside setbacks. New or amended setback regulations should revisit exemption procedures and where warranted, impose additional mitigation measures to ensure setback regulations provide adequate protections for health and safety as intended.

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Conservation partners are concerned that oil and gas development in the Prairie Pothole Region may reduce the abundance of breeding duck pairs using associated wetland habitat. We conducted wetland-based surveys for breeding pairs of 5 species of dabbling ducks in the Bakken oil field during 2015–2017 across a gradient of oil and gas development intensity to test the hypothesis that the abundance of breeding duck pairs on survey wetlands would decrease as the development of oil and gas resources increased. We included covariates traditionally used to predict breeding duck pairs (i.e. wetland size and class) and a spatiotemporal index of disturbance when developing zero-inflated Poisson models relating pair abundance to environmental predictors. Similar to past analyses, pair abundance was strongly associated with wetland size. Our results were mixed and suggested that the abundance of early and late nesting species was positively and negatively related, respectively, to an index of disturbance that was largely driven by oil and gas development. Regardless of the direction of the relationship, effect sizes were small and not considered biologically significant. Our findings indicate that in our study area, strategies to conserve wetland resources for breeding duck pairs should not deviate from previous prioritization metrics within the range of oil and gas development we observed. We believe that our findings may have implications to similar landscapes within the Bakken.• Since 2008, the oil and gas development in the North Dakota and Montana portion of Bakken Oil Formation has increased dramatically.• There is considerable overlap between the Bakken Oil Formation and important Prairie Pothole Region wetlands critical for waterfowl production.• We surveyed breeding Blue-winged Teal, Gadwall, Mallard, Northern Pintail, and Northern Shoveler pairs from 2015 to 2017 to determine if breeding pair abundance was lower in proximity to a gradient of disturbance from oil and gas development.• Our results were mixed but regardless, changes in pair abundance were small and we considered the potential biological effect to be small.• We recommend that existing conservation tools continue to be used to identify important grassland and wetland resources in the region given that we did not observe a biologically significant reduction in breeding duck pairs.

Abstract:
Migraine–an episodic disorder characterized by severe headache that can lead to disability–affects over 1 billion people worldwide. Prior studies have found that short-term exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone increases risk of migraine-related emergency department (ED) visits. Our objective was to characterize the association between long-term exposure to sources of harmful emissions and common air pollutants with both migraine headache and, among patients with migraine, headache severity.

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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:
Background. Prior studies have found that residential proximity to upstream oil and gas production is associated with increased risk of adverse health outcomes. Emissions of ambient air pollutants from oil and gas wells in the preproduction and production stages has been proposed as conferring risk of adverse health effects, but the extent of air pollutant emissions from wells is not clear. Objectives. We examined the effects of upstream oil and gas preproduction (count of drilling sites) and production (total volume of oil and gas) activities on concentrations of five ambient air pollutants in California. Methods. We obtained data on approximately 1 million daily observations from 314 monitors in the EPA Air Quality System, 2006-2019, including daily concentrations of five routinely monitored ambient air pollutants: PM2.5, CO, NO2, O3, and VOCs. We obtained data on preproduction and production operations from Enverus and the California Geographic Energy Management Division (CalGEM) for all wells in the state. For each monitor-day, we assessed exposure to upwind preproduction wells and total oil and gas production volume within 10 km. We used a panel regression approach in the analysis and fit adjusted fixed effects linear regression models for each pollutant, controlling for geographic, seasonal, temporal, and meteorological factors. Results. We observed higher concentrations of PM2.5 and CO with exposure to preproduction wells within 3 km, NO2 for wells at 1-2 km, and O3 with exposure at 2-4 km. Monitor-days with exposure to increases in production volume had higher concentrations of PM2.5, NO2, and VOCs within 1 km and higher O3 concentrations at 1-2 km. Results were robust to sensitivity analyses. Conclusion. Adjusting for geographic, meteorological, seasonal, and time-trending factors, we observed higher concentrations of ambient air pollutants at air quality monitors in proximity to preproduction wells within 4 km and producing wells within 2 km.

Abstract:
Methane emissions were measured at 6650 sites across six major oil and gas producing regions in Canada to examine regional emission trends, and to derive an inventory estimate for Canada’s upstream oil and gas sector. Emissions varied by fluid type and geographic region, with the heavy oil region of Lloydminster ranking highest on both absolute and intensity-based scales. Emission intensities varied widely for natural gas production, where older, low-producing developments such as Medicine Hat, Alberta showed high emission intensities, and newer developments in Montney, British Columbia showed emission intensities that are amongst the lowest in North America. Overall, we estimate that the Canadian upstream oil and gas methane inventory is underestimated by a factor of 1.5, which is consistent with previous studies of individual regions.

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:
Hydraulic fracturing of deep shale formations generates large volumes of wastewater that must be managed through treatment, reuse, or disposal. Produced wastewater liberates formation-derived radionuclides and contains previously uncharacterized organohalides thought to be generated within the shale well, both posing unknown toxicity to human and ecological health. Here, we assess the toxicity of 42 input media and produced fluid samples collected from four wells in the Utica formation and Marcellus Shale using two distinct endpoint screening assays. Broad spectrum acute toxicity was assessed using a bioluminescence inhibition assay employing the halotolerant bacterium Aliivibrio fischeri, while predictive mammalian cytotoxicity was evaluated using a N-acetylcysteine (NAC) thiol reactivity assay. The acute toxicity and thiol reactivity of early-stage flowback was higher than later produced fluids, with levels diminishing through time as the natural gas wells matured. Acute toxicity of early stage flowback and drilling muds were on par with the positive control, 3,5-dichlorophenol (6.8 mg L−1). Differences in both acute toxicity and thiol reactivity between paired natural gas well samples were associated with specific chemical additives. Samples from wells containing a larger diversity and concentration of organic additives resulted in higher acute toxicity, while samples from a well applying a higher composition of ammonium persulfate, a strong oxidizer, showed greater thiol reactivity, predictive of higher mammalian toxicity. Both acute toxicity and thiol reactivity are consistently detected in produced waters, in some cases present up to nine months after hydraulic fracturing. These results support that specific chemical additives, the reactions generated by the additives, or the constituents liberated from the formation by the additives contribute to the toxicity of hydraulic fracturing produced waters and reinforces the need for careful consideration of early produced fluid management.

Abstract:
Earthquakes resulting from hydraulic fracturing (HF) can have delayed triggering relative to injection commencement over a varied range of time scales, with many cases exhibiting the largest events n

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.