Repository for Oil and Gas Energy Research (ROGER)

Abstract:
Effective, considerate shale play water management supports operations and protects the environment. A parameter often overlooked is total dissolved solids (TDS) of produced water from the formation. Knowledge of TDS is important to meet these dual goals. Subsurface TDS typically increases with depth. However, produced-water samples from the Eagle Ford Shale show a strong TDS decrease by a factor of ~10 with increasing well depth (~200,000 ppm at ~2.5 km to 18,000 ppm at ~3.6 km). Water stable isotopes strongly suggest that the low TDS is not due to dilution by meteoric water. Rather, we attribute the change to smectite-to-illite conversion, in which the smectite interlayer water is released into the pore space. Depth, temperature, and other related indicators (source for K, excess silica) support such a mechanism. In addition, water-isotope patterns and 87Sr/86Sr ratios suggest a conversion operating with limited contributions external to the shale. Order-of-magnitude calculations show that the 8% of mixed-layer clay present on average in the Lower Eagle Ford Shale is sufficient to bring formation water TDS to observed levels when some of the resident water is expelled. Understanding that the low salinity is an intrinsic property of the formation water rather than due to short-term mixing allows stakeholders to have a more optimistic outlook on water recycling and on using produced water for other uses (irrigation, municipal).

Abstract:
Polyethylene glycols (PEG) and polypropylene glycols (PPG) are frequently used in hydraulic fracturing fluids and have been detected in water returning to the surface from hydraulically-fractured oil and gas wells in multiple basins. We identified degradation pathways and kinetics for PEGs and PPGs under conditions simulating a spill of produced water to shallow groundwater. Sediment-groundwater microcosm experiments were conducted using four produced water samples from two Denver Julesburg Basin wells at early and late production. High resolution mass spectrometry was used to identify the formation of mono- and di-carboxylated PEGs and mono-carboxylated PPGs, which are products of PEG and PPG biodegradation, respectively. Under oxic conditions, first-order half lives were more rapid for PEG (<0.4-1.1 d) compared to PPG (2.5-14 d). PEG and PPG degradation corresponded to increased relative abundance of primary alcohol dehydrogenase genes predicted from metagenome analysis of the 16S rRNA gene. Further degradation was not observed under anoxic conditions. Our results provide insight to the differences between degradation rates and pathways of PEGs and PPGs, which may be utilized to better characterize shallow groundwater contamination following a release of produced water.

Abstract:
Oil- and gas-produced water (PW) which contains various pollutants is an enormous threat to the environment. In this study, a novel low-cost bio-adsorbent was prepared from shrimp shell and acid-activated montmorillonite. The results of FT-IR spectroscopy, energy dispersive X-ray (EDX) analysis, and SEM-EDX technique indicated that the chitosan-activated montmorillonite (CTS-A-MMT) was prepared successfully. The synthesized CTS-A-MMT was applied to remove simultaneously five cationic and anionic metal species and crude oil from synthetic and real oilfield PW. The adsorption data indicated that crude oil and all studied metals (except As) were adsorbed to CTS-A-MMT in a monolayer model (best fitted by Langmuir model), while As adsorption fits well with Freundlich model. Kinetic models’ evaluation demonstrated that the adsorption kinetics of metals on CTS-A-MMT are initially controlled by the chemical reaction (film diffusion) followed by intra-particle diffusion. Application of the prepared CTS-A-MMT in real oilfield PW indicated removal efficiency of 65 to 93% for metals and 87% for crude oil in simultaneous removal experiments. Presence of additional ions in PW decreased the removal of studied metals and crude oil considerably; however, the concentration of the investigated pollutants in treated PW is less than the ocean discharge criteria. It is concluded that the prepared CTS-A-MMT composite is a low-cost and effective adsorbent for treating wastewater contaminated with crude oil and heavy metals (i.e., PW).

Abstract:
The paper explores the emergence of different publics for shale gas issue along the development of exploration activities in Poland. Through the concept of co-production, it is argued that publics do not pre-exist socio-technical realities but that they are organized by various actors together with these realities. The paper argues that scaling is an important aspect of the co-production of publics as it helps to navigate among them and the issues they represent and govern them according to their scalar relevance: local, regional, national or international. As political realities, publics become important terrains within which relations between state and citizens are negotiated.

Abstract:
Examining the early stages of coalition formation and how they may react to rapid institutional changes provides insight into how like-minded policy actors pursue their goals and coordinate their behavior in relatively unstable institutional systems. This study observes activity in the policy subsystem of hydraulic fracturing (fracking) in the southern Argentinian province of Neuquén. Using media sources, we identify policy actors, their support or opposition to the expansion of unconventional oil and gas production through fracking and their agreement or disagreement on the topic of fracking, both before and after Chevron and YPF (the large publicly-owned Argentinian energy company) signed a controversial accord to develop parts of the Vaca Muerta formation, one of the largest in the world. Using Social Network Analysis, we show that two coalitions (pro and anti fracking) exist, and that they exhibit a high potential for intra-coalitional coordination and inter-coalitional conflict. Following the signing of the accord, which we see as an example of an “institutional shock”, significant increases in activity and the potential for intra-coordination within the anti-fracking coalition were observed, along with an increase in the potential for conflict between the coalitions. Our results illuminate shed new light on how coalitions may form and evolve in unstable institutional systems where political power is unevenly distributed.

Abstract:
For several decades, high-salinity water brought to the surface during oil and gas (O&G) production has been treated and discharged to waterways under National Pollutant Discharge Elimination System (NPDES) permits. In Pennsylvania, USA, a portion of the treated O&G wastewater discharged to streams from 2008 to 2011 originated from unconventional (Marcellus) wells. We collected freshwater mussels, Elliptio dilatata and Elliptio complanata, both upstream and downstream of a NPDES-permitted facility, and for comparison, we also collected mussels from the Juniata and Delaware Rivers that have no reported O&G discharge. We observed changes in both the Sr/Cashell and 87Sr/86Srshell in shell samples collected downstream of the facility that corresponded to the time period of greatest Marcellus wastewater disposal (2009–2011). Importantly, the changes in Sr/Cashell and 87Sr/86Srshell shifted toward values characteristic of O&G wastewater produced from the Marcellus Formation. Conversely, shells collected upstream of the discharge and from waterways without treatment facilities showed lower variability and no trend in either Sr/Cashell or 87Sr/86Srshell with time (2008–2015). These findings suggest that (1) freshwater mussels may be used to monitor changes in water chemistry through time and help identify specific pollutant sources and (2) O&G contaminants likely bioaccumulated in areas of surface water disposal.

Abstract:
Shale gas has become an important strategic energy source with considerable potential economic benefits and the potential to reduce greenhouse gas emissions in so far as it displaces coal use. However, there still exist environmental health risks caused by emissions from exploration and production activities. In the United States, states and localities have set different minimum setback policies to reduce the health risks corresponding to the emissions from these locations, but it is unclear whether these policies are sufficient. This study uses a Gaussian plume model to evaluate the probability of exposure exceedance from EPA concentration limits for PM2.5 at various locations around a generic wellsite in the Marcellus shale region. A set of meteorological data monitored at ten different stations across Marcellus shale gas region in Pennsylvania during 2015 serves as an input to this model. Results indicate that even though the current setback distance policy in Pennsylvania (500 ft. or 152.4 m) might be effective in some cases, exposure limit exceedance occurs frequently at this distance with higher than average emission rates and/or greater number of wells per wellpad. Setback distances should be 736 m to ensure compliance with the daily average concentration of PM2.5, and a function of the number of wells to comply with the annual average PM2.5 exposure standard.Implications: The Marcellus Shale gas is known as a significant source of criteria pollutants and studies show that the current setback distance in Pennsylvania is not adequate to protect the residents from exceeding the established limits. Even an effective setback distance to meet the annual exposure limit may not be adequate to meet the daily limit. The probability of exceeding the annual limit increases with number of wells per site. We use a probabilistic dispersion model to introduce a technical basis to select appropriate setback distances.

Abstract:
In the past decade, the technological developments in the oil and natural gas extraction industry made the extraction of shale gas economically feasible and prompted local economic booms across the US. Anecdotal evidence suggests that areas with unconventional gas development experience a disproportionate increase in the young male population who are more likely to be involved in risk-taking behavior. Moreover, the sudden income gains or demographic shifts might increase the demand for various goods and services, including entertainment and illegal activities provided by the adult entertainment industry. We investigate the relationship between unconventional gas development and a variety of risk-taking outcomes such as sexually transmitted infections, and prostitution-related arrests. Our identification strategy exploits the variation in shale gas or unconventional well drilling across time and counties in conjecture with a number of datasets that allow us to investigate the potential mechanisms. Our findings indicate that Pennsylvania counties with fracking activities have higher rates of gonorrhea and chlamydia infections (7.8% and 2.6%, respectively), as well as higher prostitution related arrests (19.7%). We posit that changes in the labor market and associated impacts to income or composition of workers may play a role in the estimated effects, but we do not find evidence in support of these hypotheses.

Abstract:
At the forefront of the discussions about climate change and energy independence has been the process of hydraulic fracturing, which utilizes large amounts of water, proppants, and chemical additives to stimulate sequestered hydrocarbons from impermeable subsurface strata. This process also produces large amounts of heterogeneous flowback and formation waters, the subsurface disposal of which has most recently been linked to the induction of anthropogenic earthquakes. As such, the management of these waste streams has provided a newfound impetus to explore recycling alternatives to reduce the reliance on subsurface disposal and fresh water resources. However, the biogeochemical characteristics of produced oilfield waste render its recycling and reutilization for production well stimulation a substantial challenge. Here we present a comprehensive analysis of produced waste from the Eagle Ford shale region before, during, and after treatment through adjustable separation, flocculation, and disinfection technologies. The collection of bulk measurements revealed significant reductions in suspended and dissolved constituents that could otherwise preclude untreated produced water from being utilized for production well stimulation. Additionally, a significant step-wise reduction in pertinent scaling and well-fouling elements was observed, in conjunction with notable fluctuations in the microbiomes of highly variable produced waters. Collectively, these data provide insight into the efficacies of available water treatment modalities within the shale energy sector, which is currently challenged with improving the environmental stewardship of produced water management.

Abstract:
The list of iodinated disinfection byproducts (iodo-DBPs) includes some of the most genotoxic and cytotoxic DBPs discovered to date. Therefore, human exposure should be minimized by reducing their presence in drinking water. This manuscript reviews the main iodo-DBP formation pathways during water disinfection, with focus on the advances reported in the last two years. We discuss the effect of iodine sources other than iodine salts, e.g., iodinated contrast media and iodate, on iodo-DBP formation. In addition, we review the anthropogenic activities (like oil and gas extraction, dairy industry, seawater desalination or advanced oxidation treatments with persulfate) that may release iodo-DBPs to the aquatic environment or increase the potential of source waters to generate these compounds when disinfected.

Abstract:
The overall mass of sodium chloride salt used to treat icy roads can be significantly reduced by pretreating roads or prewetting dry rock salt with concentrated brine solutions. Brine solutions can be made from rock salt; however, an alternative source of brine for some communities is brine that is a waste product of oil and gas extraction. This study compares contaminant chemistry of brine made from rock salt with literature data on oil and gas well brine from conventional and unconventional wells. In addition to reviewing existing literature, this paper analyzes four rock salt samples for a suite of chemical constituents. Maximum reported levels of some harmful contaminants are higher for well brines than for rock salt brines and are higher for unconventional than for conventional well brines. Because the regulatory structure for using well brines varies among states, the authors recommend a consistent approval process for permitting the use of waste brines that includes specific maximum allowable limits for potentially harmful contaminants, and that each batch of solution be tested before use. Although the use of brine, including waste brine, can reduce the overall amount of salt needed for snow and ice control, adequate steps should be taken to ensure the safety of the brine solutions before they are used.

Abstract:
To assess the risk of underground sources of drinking water contamination by barium (Ba) present in petroleum produced water disposed into deep saline aquifers, we examined the effect of salinity (NaCl), competition of cations (Ca, Mg), temperature (22 and 60°C), and organic fracturing additives (guar gum) on the sorption and transport of Ba in dolomites and sandstones. We found that at typical concentration levels of NaCl, Ca, and Mg in petroleum produced water, Ba sorption in both dolomites and sandstones is inhibited by the formation of Ba(Cl)+ complexes in solution and/or the competition of cations for binding sites of minerals. The inhibition of Ba sorption by both mechanisms is greater in dolomites than in sandstones. This is reflected by a larger decrease in the breakthrough times of Ba through dolomites than through sandstones. We found that the presence of guar gum has little influence on the sorption and thus the transport of Ba in both dolomites and sandstones. Contrary to most heavy metals, Ba sorption in both dolomites and sandstones decreases with increasing temperature, however the reducing effect of temperature on Ba sorption is relevant only at low salinity conditions. Higher inhibition of Ba sorption in dolomites than in sandstones is due to the greater reactivity of dolomite over sandstone. The results of this study which includes the formulation of a reactive transport model and estimation of partition coefficients of Ba in dolomites and sandstones have significant implications in understanding and predicting the mobility and transport of Ba in deep dolomite and sandstone saline aquifers.

Abstract:
Site-specific and regional analysis of time-series hydrologic and geochemical data collected from 15 monitoring wells in the Piceance Basin indicated that a leaking gas well contaminated shallow groundwater with thermogenic methane. The gas well was drilled in 1956 and plugged and abandoned in 1990. Chemical and isotopic data showed the thermogenic methane was not from mixing of gas-rich formation water with shallow groundwater or natural migration of a free-gas phase. Water-level and methane-isotopic data, and video logs from a deep monitoring well, indicated that a shale confining layer ~125m below the zone of contamination was an effective barrier to upward migration of water and gas. The gas well, located 27m from the contaminated monitoring well, had ~1000m of uncemented annular space behind production casing that was the likely pathway through which deep gas migrated into the shallow aquifer. Measurements of soil gas near the gas well showed no evidence of methane emissions from the soil to the atmosphere even though methane concentrations in shallow groundwater (16 to 20mg/L) were above air-saturation levels. Methane degassing from the water table was likely oxidized in the relatively thick unsaturated zone (~18m), thus rendering the leak undetectable at land surface. Drilling and plugging records for oil and gas wells in Colorado and proxies for depth to groundwater indicated thousands of oil and gas wells were drilled and plugged in the same timeframe as the implicated gas well, and the majority of those wells were in areas with relatively large depths to groundwater. This study represents one of the few detailed subsurface investigations of methane leakage from a plugged and abandoned gas well. As such, it could provide a useful template for prioritizing and assessing potentially leaking wells, particularly in cases where the leakage does not manifest itself at land surface.

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This research exploits the introduction of shale gas wells in Pennsylvania in response to growing controversy around the drilling method of hydraulic …

Abstract:
Seismicity induced by fluid perturbations became an important societal concern since felt earthquakes (Mw up to 6) occurred after anthropogenic activi…

Abstract:
Research on unconventional oil and gas (UOG) development has focused so intently on hydraulic fracturing that it has overlooked “fracking's” partner technology, horizontal drilling (HZD), which now enables operators to drill more than 2.5 miles. This innovation merits examination because it generates opportunities and challenges – in tension – for regions experiencing UOG development. HZD allows operators to condense their surface impacts by drilling multiple wells per pad. This consolidation benefits the many in a given extractive area, but at the expense of the few who live near intensified sites. HZD also allows operators to more flexibly position these large well pads. Combined, these drilling innovations are further splintering an already fragmented UOG governance space and creating novel procedural fairness challenges, especially in cities. This study offers the concept of “piecemeal participation” to describe these challenges, drawing from a case study in Colorado. Piecemeal participation occurs when governments structure public input on a site-by-site basis, while operators, leveraging HZD's reach and flexibility, plan drilling and weigh alternative drilling locations at the scale of the city. The analysis evaluates piecemeal participation using standard procedural fairness criteria, generating findings of broader relevance as urban areas anticipate UOG development and HZD worldwide.

Abstract:
The U.S. is now the global leader in natural gas production. The federal government is changing policies and priorities to expand natural gas export to foreign energy markets. Such an expansion requires increased pipeline capacity and the development of export terminals for shipping. While natural gas export is a burgeoning energy and environmental issue, we know little about what influences public support/opposition for the practice. Such information is vital to all levels of government and stakeholders. Using a national online survey sample (n = 1042), we examine what factors influence public support/opposition. Results of regression analysis indicate that supporters tend to be male, hold a bachelor's degree or higher, wealthier, politically conservative, and reference affective images of the economy, energy, and trade. In contrast, opponents tend to be women, politically liberal, and reference affective images related to keeping natural gas in the U.S., the environment, and hydraulic fracturing. Based on these findings, we discuss implications for energy policy, public communication about this issue, and future research.

Abstract:
Oil and gas extraction, especially via unconventional means like hydraulic fracturing, is hailed as an economic boon by many commentators and political leaders. However, empirical evidence is limited. In this article, we consider the socioeconomic effects (particularly, related to poverty, employment, income, and wages) of unconventional oil and gas extraction using a national data set of U.S. counties. We use a novel between- and within-county random effects modeling strategy to capture both resource curse and boomtown dynamics. Further, we allow the effect of oil and gas development to be conditioned by county rurality. Broadly, our findings suggest that oil and gas development has very complex effects at the county level. Within-county growth in oil and gas production slightly improves most economic outcomes, but counties that specialize in oil and gas development tend to perform worse than other counties. We find that, in general, the effect of within-county oil and gas production is not significantly moderated by county rurality.

Abstract:
Environmental justice and social movements scholarship demonstrates how not-in-my-backyard activism by more privileged communities leaves the disadvantaged with locally unwanted land uses. Yet it overlooks instances of local support for risky industries. Our ethnographic case shows how a rural, white, mixed-income Pennsylvania community adopted a please-in-my-backyard stance toward shale gas extraction (fracking). Residents invited development on their land and supported it through quiet mobilization. While landowners prioritized benefits over risks, economics cannot fully explain their enthusiasm. Consistent with public opinion research, partisan identities and community obligations undergirded industry support even when personal benefits were limited. Devotion to self-reliance and property rights led residents to defend landowners' freedom to lease their land. Cynicism toward government precluded endorsing environmental regulation, and the perception of antifracking activists as liberal outsiders linked support for fracking with community solidarity. This case illustrates why communities may champion risky industries and complicates theories of nonmobilization.

Abstract:
In the past decade, the technological developments in the oil and natural gas extraction industry made the extraction of shale gas economically feasible and prompted local economic booms across the US. Anecdotal evidence suggests that areas with unconventional gas development experience a disproportionate increase in the young male population who are more likely to be involved in risk taking behavior. Moreover, the sudden income gains or demographic shifts might increase the demand for various goods and services, including entertainment and illegal activities provided by the adult entertainment industry. We investigate the relationship between unconventional gas development and a variety of risk-taking outcomes such as sexually transmitted infections, and prostitution-related arrests. Our identification strategy exploits the variation in shale gas or unconventional well drilling across time and counties in conjecture with a number of datasets that allow us to investigate the potential mechanisms. Our findings indicate that Pennsylvania counties with fracking activities have higher rates of gonorrhea and chlamydia infections (7.8% and 2.6%, respectively), as well as higher prostitution related arrests (19.7%). We posit that changes in the labor market and associated impacts to income or composition of workers may play a role in the estimated effects, but we do not find evidence in support of these hypotheses. Published by Elsevier B.V.

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Research Highlight

Abstract:
Seismic limits for hard and soft rock Induced earthquakes from oil, gas, and geothermal energy exploration projects can damage infrastructure and concern the public. However, it remains unclear how far away from an injection site an earthquake can still be triggered. Goebel and Brodsky looked at 18 different earthquake-producing injection sites around the world to address this issue. Injecting fluid into softer layers increased the range for seismic hazard, whereas harder basement rock better confined the fluid. These findings should be considered when regulating and managing projects with the potential to induce seismicity. Science, this issue p. 899 Fluid injection can cause extensive earthquake activity, sometimes at unexpectedly large distances. Appropriately mitigating associated seismic hazards requires a better understanding of the zone of influence of injection. We analyze spatial seismicity decay in a global dataset of 18 induced cases with clear association between isolated wells and earthquakes. We distinguish two populations. The first is characterized by near-well seismicity density plateaus and abrupt decay, dominated by square-root space-time migration and pressure diffusion. Injection at these sites occurs within the crystalline basement. The second population exhibits larger spatial footprints and magnitudes, as well as a power law–like, steady spatial decay over more than 10 kilometers, potentially caused by poroelastic effects. Far-reaching spatial effects during injection may increase event magnitudes and seismic hazard beyond expectations based on purely pressure-driven seismicity. The seismic hazard distance from injection wells is dependent on rock type and fault density. The seismic hazard distance from injection wells is dependent on rock type and fault density.

Abstract:
On-site flowback treatment systems are typically rated and selected based on three fundamental categories: satisfying customer needs (e.g. meeting effluent quality, capacity, delivery time and time required to reach stable and steady effluent quality), common features comparison (e.g. treatment costs, stability of operation, scalability, logistics, and maintenance frequency) and through substantial product differentiation such as better service condition, overcoming current market limitations (e.g. fouling, salinity limit), and having lower environmental footprints and emissions. For treatment of flowback, multiple on-site treatment systems are available for primary separation (i.e. reducing TSS concentrations and particle size below 25 μm for disposal), secondary separation (i.e. removing TSS, iron and main scaling ions, and reducing particle size up to 5 μm for reuse), or tertiary treatment (i.e. reducing TDS concentration in the permeate/distillate to below 500 mg/L) for recycling or discharge. Depending on geographic features, frac-fluid characteristics, and regulatory aspects, operators may choose disposal or reuse of flowback water. Among these approaches, desalination is the least utilized option while in the majority of cases on-site basic separation is selected which can result in savings up to $306,800 per well. Compared to desalination systems, basic separation systems (e.g. electrocoagulation, dissolved air floatation) have higher treatment capacity (159–4133 m3/d) and specific water treatment production per occupied space (8.9–58.8 m3/m2), lower treatment costs ($2.90 to $13.30 per m3) and energy demand, and finally generate less waste owing to their high recovery of 98–99.5%, which reduces both operator costs and environmental burdens.

Abstract:
This article examines shale gas development in Mexico. Its qualitative analysis focuses on the regulatory setting, challenges and perspectives, and on the feasibility to ‘smartly regulate’ this issue. The analysis demonstrates that Mexico’s shale gas development is especially difficult to regulate due to its high complexity. Increasing environmental impacts, lack of regulatory and industry expertise and a novel regulatory setting with multiple regulators and levels of accountability increase the regulatory challenge. Innovative and complementary regulatory tools, best practice and specialised regulation are likely to lessen the environmental impacts associated with shale gas development and regulators have already made significant progress in this direction. The first competitive bidding for unconventional terrestrial resources was announced in March 2018 and is the tip of the iceberg of commercial production of Mexico´s vast shale gas resources. Nevertheless, the particular complexity of regulating shale gas development in Mexico, suggests that even if ‘smart regulation’ is possible and is properly implemented substantial adverse environmental impacts may still occur.

Abstract:
Natural gas and oil extraction, while meeting much of our current energy demand, also generates large volumes of waste water (“produced water”) that creates risks for groundwater contamination when spilled. Weld County, Colorado, where the majority of extraction occurs in Colorado, was used as a case study to understand how groundwater impacts were related to spill details including volumes spilled, area impacted, and depth to groundwater. Publically available produced water production and spill data were analyzed to determine if improvements could be made to reduce the water intensity of oil and gas drilling. The depth to groundwater significantly affected the likelihood of groundwater contamination at spill sites. Since spills often occur at oil and gas well pads, extraction site selection should preclude those areas that have shallow groundwater. Evaluation of produced water generation and produced water spilled reveal that although larger-scale operations did generate less relative produced water per energy generated, the total volume of produced water spilled by an operator was linearly correlated with the scale of the operation. These results suggest that employing fewer, large-scale operators would help to reduce the overall volume of water generated but not the overall volume spilled. The results from this research have important regulation and policy implications that can help mitigate the increased threat of groundwater contamination from produced water spills.

Abstract:
. Large-eddy simulations (LES) coupled to a model that simulates methane emissions from oil and gas production facilities are used to generate realistic distributions of meteorological variables and methane concentrations. These are sampled to obtain simulated observations used to develop and evaluate source term estimation (STE) methods. A widely used EPA STE method (OTM33A) is found to provide emission estimates with little bias when averaged over six time-periods and seven well-pads. Sixty-four percent of the emissions estimated with OTM33A are within +/-30% of the simulated emissions, showing slightly larger spread than the 72% found previously using controlled release experiments. A newly developed method adopts the OTM33A sampling strategy and uses a variational or a stochastic STE approach coupled to an LES to obtain a better fit to the sampled meteorological conditions and to account for multiple sources within the well-pad. This method can considerably reduce the spread of the emissions estimates compared to OTM33A (92-95% within +/-30% percent error), but it is associated to a substantial increase in computational cost due to the LES. It thus provides an alternative when the additional costs can be afforded to obtain more precise emission estimates.

Abstract:
Access to water, in sufficient quantities and of sufficient quality is vital for human health. The United Nations Committee on Economic, Social and Cultural Rights (in General Comment 15, drafted 2002) argued that access to water was a condition for the enjoyment of the right to an adequate standard of living, inextricably related to the right to the highest attainable standard of health, and thus a human right. On 28 July 2010 the United Nations General Assembly declared safe and clean drinking water and sanitation a human right essential to the full enjoyment of life and all other human rights. This paper charts the international legal development of the right to water and its relevance to discussions surrounding the growth of unconventional energy and its heavy reliance on water. We consider key data from the country with arguably the most mature and extensive industry, the USA, and highlight the implications for water usage and water rights. We conclude that, given the weight of testimony of local people from our research, along with data from scientific literature, non-governmental organization (NGO) and other policy reports, that the right to water for residents living near fracking sites is likely to be severely curtailed. Even so, from the data presented here, we argue that the major issue regarding water use is the shifting of the resource from society to industry and the demonstrable lack of supply-side price signal that would demand that the industry reduce or stabilize its water demand per unit of energy produced. Thus, in the US context alone, there is considerable evidence that the human right to water will be seriously undermined by the growth of the unconventional oil and gas industry, and given its spread around the globe this could soon become a global human rights issue.

Abstract:
Unconventional and conventional oil and gas (O&G) operations raise public health concerns, such as the potential impacts from trucking activity in communities that host these operations. In this work, we used two approaches to evaluate accidents in relation to O&G activities in the State of Colorado. First, we calculated the rate of truck accidents by computing the ratio of accident count and county population. When comparing counties with increased O&G operations to counties with less activity, we found that counties with more activity have greater rates of truck traffic accidents per capita (Rate Ratio = 1.07, p < 0.05, 95% CI: 1.01–1.13). Second, we laid a grid over the eleven counties of interest and counted, for each cell, the number of truck accidents, the number of multivehicle accidents with injuries, the number of homes, and the number of O&G wells. We then applied hurdle count models, using the accident counts as the outcomes and the number of homes and number of wells as independent variables. We found that both independent variables are significant predictors of truck accidents and multivehicle truck accidents. These accidents are of concern since they can have an impact on the people who live near O&G operations.

Abstract:
This work describes the discovery of amino-polyethylene-glycols, amino-polyethylene-glycol-carboxylates, and amino-polyethylene-glycol-amines in 20 produced water-samples from hydraulic fracturing in the western United States. These compounds, with masses in the range of m/z 120–986, were identified using solid phase extraction and liquid chromatography/quadrupole-time-of-flight mass spectrometry. The polymeric sorbent, Oasis HLB, gave the best recovery for all three ethoxylated surfactants and desalted the samples, which significantly reduced suppression of the mass spectral signal allowing detection and identification. The Kendrick mass defect, mass spectra, fragmentation pathways, and pure standards were used for confirmation. Finally, because these compounds are not explicitly listed in FracFocus reports, rather they are categorized as a proprietary surfactant blend; their identification is an important step in understanding the chemistry, treatment, and possible toxicity of hydraulic fracturing wastewater.

Abstract:
The application of horizontal drilling and hydraulic fracturing has enabled access to previously unrecoverable gas reservoirs. This method uses large quantities of water and the likely presence of NORM in the water that flows up to the wells have caused some concerns. In this study, a new cation resin, RSM-25HP, was compared to Dowex 50W-X8 resin for its ability to separate radium from produced water. Our results show that the RSM resin was able to retain barium and radium at higher acidities compared to the Dowex resin and could provide a higher degree of separation in the flowback water.

Abstract:
Over 4 million Americans live within 1.6km of an unconventional oil and gas (UO&G) well, potentially placing them in the path of toxic releases. We evaluated relationships between residential proximity to UO&G wells and (1) water contamination and (2) health symptoms in an exploratory study. We analyzed drinking water samples from 66 Ohio households for 13 UO&G-related volatile organic compounds (VOCs) (e.g., benzene, disinfection byproducts [DBPs]), gasoline-range organics (GRO), and diesel-range organics). We interviewed participants about health symptoms and calculated metrics capturing proximity to UO&G wells. Based on multivariable logistic regression, odds of detection of bromoform and dibromochloromethane in surface water decreased significantly as distance to nearest UO&G well increased (odds ratios [OR]: 0.28–0.29 per km). Similarly, distance to nearest well was significantly negatively correlated with concentrations of GRO and toluene in ground water (rSpearman: −0.40 to −0.44) and with concentrations of bromoform and dibromochloromethane in surface water (rSpearman: −0.48 to −0.50). In our study population, those with higher inverse-distance-squared-weighted UO&G well counts within 5km around the home were more likely to report experiencing general health symptoms (e.g. stress, fatigue) (OR: 1.52, 95%CI: 1.02–2.26). This exploratory study, though limited by small sample size and self-reported health symptoms, suggests that those in closer proximity to multiple UO&G wells may be more likely to experience environmental health impacts. Further, presence of brominated DBPs (linked to UO&G wastewater) raises the question of whether UO&G activities are impacting drinking water sources in the region. The findings from this study support expanded studies to advance knowledge of the potential for water quality and human health impacts; such studies could include a greater number of sampling sites, more detailed chemical analyses to examine source attribution, and objective health assessments.

Abstract:
This perspective paper examines the current policy landscape for hydraulic fracturing in China, with a focus on the role of public attitudes toward shale gas in China. We highlight the need for further research on public perceptions and responses in a non-democratic society, both for the potential protection of residents who might be affected by the technology as well the valuable research data that can be contrasted with public perspectives and engagement in other countries. Although the empirical findings presented here are limited due to this being very preliminary research, our goal is to shed light on what existing data shows about current understanding and perceptions. We discuss preliminary data collected during a research trip to Beijing in late December 2017, and contrast it with the few empirical studies on China that exist to date (Sher and Wu, 2018; Yu et al., 2018). Our research demonstrates the need for further investigation of understanding and perceptions of shale gas in China, particularly as other countries (EXAMPLES) are beginning to look at expanding their own shale gas resources. A reflection on this will also lead to a discussion of the extent to which data from China does or does not relate to that from other nations.

Abstract:
Emerging evidence indicates that proximity to unconventional oil and gas development (UOGD) is associated with health outcomes. There is intense debate about “How close is too close?” for maintaining public health and safety. The goal of this Delphi study was to elicit expert consensus on appropriate setback distances for UOGD from human activity. Three rounds were used to identify and seek consensus on recommended setback distances. The 18 panelists were health care providers, public health practitioners, environmental advocates, and researchers/scientists. Consensus was defined as agreement of ≥70% of panelists. Content analysis of responses to Round 1 questions revealed four categories: recommend setback distances; do not recommend setback distances; recommend additional setback distances for vulnerable populations; do not recommend additional setback distances for vulnerable populations. In Round 2, panelists indicated their level of agreement with the statements in each category using a five-point Likert scale. Based on emerging consensus, statements within each category were collapsed into seven statements for Round 3: recommend set back distances of <¼ mile; ¼—½ mile; 1–1 ¼ mile; and ≥ 2 mile; not feasible to recommend setback distances; recommend additional setbacks for vulnerable groups; not feasible to recommend additional setbacks for vulnerable groups. The panel reached consensus that setbacks of < ¼ mile should not be recommended and additional setbacks for vulnerable populations should be recommended. The panel did not reach consensus on recommendations for setbacks between ¼ and 2 miles. The results suggest that if setbacks are used the distances should be greater than ¼ of a mile from human activity, and that additional setbacks should be used for settings where vulnerable groups are found, including schools, daycare centers, and hospitals. The lack of consensus on setback distances between 1/4 and 2 miles reflects the limited health and exposure studies and need to better define exposures and track health.

Abstract:
Membrane distillation (MD) has great potentials to treat produced water in energy industries. However, volatile organic compounds (VOCs) existing in the produced water added in the fracking process can hinder the treatment process regarding two aspects: permeate quality and MD flux performance. To address this challenge, this study aims to systematically study the effects of the VOCs on the MD permeation performance and permeate quality, and the mechanism of its penetration. Acetic acid, ethylene glycol, isopropyl alcohol (IPA), and 2-Butoxyethanol (2-BE), which are commonly found in the produced water, were extensively investigated and their impacts were reviewed and compared. Among all the VOCs, 2-BE had the highest mass transfer despite its low vapour pressure and large molecule weight. Some of the VOCs had surfactant properties, which meant they could penetrate the membrane pores easily during MD process. In long-term operation, pore wetting started to appear as the salt rejection was dropping in the MD process, and flux was also decreasing. Based on the results, this study suggested that the strength of surfactant properties and intra-molecular hydrogen bonds between water molecules and VOCs are as significant as vapour pressure for the VOCs in terms of mass transfer efficiency in MD system.

Abstract:
Sustainable wastewater management strategies are required to further minimize impacts of high-volume hydraulic fracturing (HVHF) as current practices such as reuse or direct disposal have long term limitations. Membranes can provide superior effluent quality in HVHF wastewater treatment, but the application of these systems is severely limited by membrane fouling. However, the key fouling components in HVHF wastewater have not yet been clearly identified and characterized. Here we demonstrate that fouling of microfiltration membranes by synthetic flowback water is mostly due to polyacrylamide (PAM), a major additive in slickwater fracturing fluids. A synthetic fracturing fluid was incubated with Marcellus Shale under HVHF conditions (80 degrees C, 83 bar, 24 h) to generate synthetic flowback water. Different HVHF conditions and fracturing fluid compositions generated a fouling index for flowback water ranging from 0.1 to 2000 m(-1), with these values well correlated with the peakmolecular weight (MW) (ranging from 10 to 1.5 x 10(4) kDa) and the concentration of high MW components in the water. The lowest fouling index was observed when PAM was further degraded by ammonium persulfate under HVHF conditions, although this is infrequently used with PAM in current fracturing operations. These results highlight the importance of PAM and its degradation products in fouling of subsequent membrane systems, providing insights that can help in the development of effective treatment processes for HVHF wastewater.

Abstract:
The oil and gas extraction industry is an energy-intensive and high CO2 emission sector in China. This study estimates the cost-effective CO2 emission reduction potentials until 2050 by classifying key low-carbon technology bundles and investigating the energy efficiency, market penetration rate, and emission reduction cost of each technology bundle. A bottom-up technical evaluation model is established to give a comprehensive perspective to the Chinese oil and gas extraction industry and policymakers about the emission reduction potential and its associated cost. Results show that the carbon emission reduction potential in the Chinese oil and gas extraction industry in 2050 can reach 16.71 million tons in the case of all low-carbon technologies available and that the decrease rate can be as high as 14.3%. The contributions of emission reductions are mainly the improvement of energy efficiency, the transformation of production process, and the utilization of new energy sources. Most low-carbon technologies are cost-effective, with an average annual cost savings of 71.43 billion RMB. Nonetheless, the diffusions of low-carbon technologies are still significantly affected by energy price volatility and firms' expectations of future investment risk.

Abstract:
New applications of hydraulic fracturing (HF) methods to release natural gas from shale deposits have emerged as a hotly contested political issue. Consequently, researchers commonly seek to identify factors shaping public perceptions of this technology. While research conducted in North America has focused primarily on the United States, this paper contributes to a growing body of work examining Canadian perceptions toward HF. We build on the existing regionally-focused literature on public perceptions of HF in Canada with an analysis of data collected from a nationally-representative (n = 2012) survey of attitudes toward hydraulic fracturing administered to the adult Canadian population in 2016. We find that an individual’s cultural biases are strong predictors of their attitudes toward hydraulic fracturing, and that these effects are moderated by levels of issue familiarity. Analysis of an embedded survey experiment further reveals that attitudes in Canada are somewhat affected by cues regarding the developer’s status (i.e. whether a Canadian, American or government-owned corporation), and that a nationalist bias is especially prominent among people with hierarchical predispositions. We further find that familiarity with hydraulic fracturing is associated with significantly less support, and that this relationship is moderated by a respondent’s region of residence. We discuss these findings in light of the existing literature and outline areas for future research.

Abstract:
The extensive application of hydraulic fracturing technology has significantly promoted the large-scale development of shale gas. However, it is a great challenge for shale gas extraction to effectively manage large-volume flowback water (FW) with high salinity and complex organic substances. Here, we report an aerobic granular sludge (AGS) tolerable to high salinity, and suited to the treatment of FW. The performance of a sequencing batch reactor (SBR) with the AGS for the treatment of the synthetic FW and the microbial community structure at different salinity levels were investigated. The AGS fed with synthetic FW possessed a larger average particle size and a higher settling rate (50 m h−1). When NaCl concentration increased to 50.0 g L−1, the removal efficiency of total organic carbon (TOC) increased to 79 ± 1%, and the removal rate of polyacrylamide (PAM) raised up to 42.7 ± 0.7 g m−3 d−1. Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Sphingobacteriia dominated in the microbial community of AGS. Cellvibrionaceae, Rhodocyclaceae, Enterobacteriaceae, Moraxellaceae, Pseudomonadaceae, and Halomonadaceae belonging to Betaproteobacteria and Gammaproteobacteria played important role in degrading PAM, polycyclic aromatic hydrocarbons (PAH), and some other organics in FW at high salinity. These results suggest that an AGS-based SBR is a promising technology for the treatment of FW.

Abstract:
Public and stakeholder engagement with shale development is difficult, but essential. We review 26 engagement processes carried out by US and Canadian companies, alliances, government agencies, academics and activists; systematically exploring who participates, the stage at which engagements take place, aims and methods, provision for multiway engagement, and issues of credibility. We find a multitude of actors carrying out engagement using a variety of formats, ranging from barbeque events and town hall meetings to citizen science and in-depth qualitative research. Whilst we find many strengths, we also highlight a number of weaknesses. Much of this engagement does not occur at the earliest stages of development, and rarely asks the most fundamental question -whether shale development should proceed at all- instead commonly focusing on questions of impact minimisation, regulation and gaining support. Furthermore, the majority of activities tend to elicit the responses of interested and affected parties, with much less attention to views of the wider public. We reflect on what may be limiting engagement practice, and discuss how engagement might be improved.

Abstract:
Radium in hydraulic fracturing wastewaters derives from two isotopically distinct end-members in the shale, labile 228Ra hosted by mineral surfaces (226Ra/228Ra atom ratio ~250) and exchangeable 226Ra hosted by organic surfaces (226Ra/228Ra ~10,000). Here we use mass balance and isotope mixing models to reconcile extraction of Ra from these phases with mechanisms of Marcellus wastewater production. Radium isotopic mass balance requires that the characteristic water-rock ratio between wastewater and shale is exceedingly low, on the order of 0.04, and that this ratio decreases with time during wastewater production. An evolving water-rock interaction drives increasing Ra concentrations (=[Ra]) and 226Ra/228Ra ratios during wastewater production, all mediated by increasing [Ca2+] that favors desorption of 226Ra from organics. Our observations and models of Ra isotope geochemistry are best reconciled with observations of water and salinity mass balance, δ18O, Na-Br-Cl, and 87Sr/86Sr if wastewater is produced by mixing of injected fluids with a limited volume of pore brine (on the order of 13% by volume), accompanied by contemporaneous extraction of excess alkaline earth elements by water-rock exchange. Validated using Ra isotope data, this model attributes the extreme salinity and [Ra] in wastewaters to the progressive, hydrologic enrichment of injected fluids during hydraulic fracturing.

Abstract:
The recent increase in unconventional oil and gas exploration and production has prompted a large amount of research on hydraulic fracturing, but the majority of chemical reactions between shale minerals and organic matter with fracturing fluids are not well understood. Organic matter, primarily in the form of kerogen, dominates the transport pathways for oil and gas; thus any alteration of kerogen (both physical and chemical properties) upon exposure to fracturing fluid may impact hydrocarbon extraction. In addition, kerogen is enriched in metals, making it a potential source of heavy metal contaminants to produced waters. In this study, we reacted two different kerogen isolates of contrasting type and maturity (derived from Green River and Marcellus shales) with a synthetic hydraulic fracturing fluid for two weeks in order to determine the effect of fracturing fluids on both shale organic matter and closely associated minerals. ATR-FTIR results show that the functional group compositions of the kerogen isolates were in fact altered, although by apparently different mechanisms. In particular, hydrophobic functional groups decreased in the Marcellus kerogen, which suggests the wettability of shale organic matter may be susceptible to alteration during hydraulic fracturing operations. About 1% of organic carbon in the more immature and Type I Green River kerogen isolate was solubilized when it was exposed to fracturing fluid, and the released organic compounds significantly impacted Fe oxidation. Based on the alteration observed in both kerogen isolates, it should not be assumed that kerogenic pores are chemically inert over the timeframe of hydraulic fracturing operations. Shifts in functional group composition and loss of hydrophobicity have the potential to degrade transport and storage parameters such as wettability, which could alter hydrocarbon and fracturing fluid transport through shale. Additionally, reaction of Green River and Marcellus kerogen isolates with low pH solutions (full fracturing fluid, which contains hydrochloric acid, or pH 2 water) mobilized potential trace metal(loid) contaminants, primarily S, Fe, Co, Ni, Zn, and Pb. The source of trace metal(loid)s varied between the two kerogen isolates, with metals in the Marcellus shale largely sourced from pyrite impurities, whereas metals in the Green River shale were sourced from a combination of accessory minerals and kerogen.

Abstract:
Background Recent trends have witnessed the global growth of unconventional oil and gas (UOG) production. Epidemiologic studies have suggested associations between proximity to UOG operations with increased adverse birth outcomes and cancer, though specific potential etiologic agents have not yet been identified. To perform effective risk assessment of chemicals used in UOG production, the first step of hazard identification followed by prioritization specifically for reproductive toxicity, carcinogenicity and mutagenicity is crucial in an evidence-based risk assessment approach. To date, there is no single hazard classification list based on the United Nations Globally Harmonized System (GHS), with countries applying the GHS standards to generate their own chemical hazard classification lists. A current challenge for chemical prioritization, particularly for a multi-national industry, is inconsistent hazard classification which may result in misjudgment of the potential public health risks. We present a novel approach for hazard identification followed by prioritization of reproductive toxicants found in UOG operations using publicly available regulatory databases. Methods GHS classification for reproductive toxicity of 157 UOG-related chemicals identified as potential reproductive or developmental toxicants in a previous publication was assessed using eleven governmental regulatory agency databases. If there was discordance in classifications across agencies, the most stringent classification was assigned. Chemicals in the category of known or presumed human reproductive toxicants were further evaluated for carcinogenicity and germ cell mutagenicity based on government classifications. A scoring system was utilized to assign numerical values for reproductive health, cancer and germ cell mutation hazard endpoints. Using a Cytoscape analysis, both qualitative and quantitative results were presented visually to readily identify high priority UOG chemicals with evidence of multiple adverse effects. Results We observed substantial inconsistencies in classification among the 11 databases. By adopting the most stringent classification within and across countries, 43 chemicals were classified as known or presumed human reproductive toxicants (GHS Category 1), while 31 chemicals were classified as suspected human reproductive toxicants (GHS Category 2). The 43 reproductive toxicants were further subjected to analysis for carcinogenic and mutagenic properties. Calculated hazard scores and Cytoscape visualization yielded several high priority chemicals including potassium dichromate, cadmium, benzene and ethylene oxide. Conclusions Our findings reveal diverging GHS classification outcomes for UOG chemicals across regulatory agencies. Adoption of the most stringent classification with application of hazard scores provides a useful approach to prioritize reproductive toxicants in UOG and other industries for exposure assessments and selection of safer alternatives.

Abstract:
ABSTRACT. Outside the US, the commercial development of shale gas and oil will need to overcome significant legal and regulatory challenges if it is ever to ta

Abstract:
The global energy landscape has significantly changed in the past several years because horizontal drilling and hydraulic fracturing enable unconventional oil and gas extraction from previously inaccessible shale formations. However, opportunities and challenges coexist. Large volumes of freshwater consumed and wastewater discharge increasingly affect the environment and ecosystem. Much freshwater is pumped into deep formations during hydraulic fracturing process, and flowback with high-salinity brines, producing large volumes of wastewater. Such wastewater contains not only many toxic chemicals and high levels of total dissolved solids, but also abundant stratigraphic minerals and radioactive substances, which may pose a serious risk to the surrounding environment and public health. One of the greatest challenges for current oil and gas extraction is handling those wastewaters in a reasonable and efficient way. This paper described the current methods for dealing with these challenges and put forward some suggestions and expectations for future management of water resources in hydraulic fracturing. Open image in new window Graphical Abstract

Abstract:
Unconventional oil and gas exploration in the United States has experienced a period of rapid growth, followed by several years of limited production due to falling and low natural gas and oil prices. Throughout this transition, the water use for hydraulic fracturing and wastewater production in major shale gas and oil production regions has increased; from 2011 to 2016, the water use per well increased up to 770%, while flowback and produced water volumes generated within the first year of production increased up to 1440%. The water-use intensity (that is, normalized to the energy production) increased ubiquitously in all U.S. shale basins during this transition period. The steady increase of the water footprint of hydraulic fracturing with time implies that future unconventional oil and gas operations will require larger volumes of water for hydraulic fracturing, which will result in larger produced oil and gas wastewater volumes.

Abstract:
Changes to the material and social systems that underpin energy infrastructures are inextricably linked to energy justice concerns, and the timeframes of those changes significantly affect their outcomes. Temporal aspects of energy initiatives and their impacts are thus an important site for examining emergent public views on new energy proposals, inequality, and energy justice. We propose urgency is a particularly rich concept through which to study (i) the justice and socioenvironmental implications of energy systems and technological change and (ii) how people make sense of contested energy timeframes. Here, we present findings from a series of public deliberation workshops held in the United States and United Kingdom to discuss projected impacts of shale oil and gas extraction by hydraulic fracturing. We encountered critical similarities across sites, as in widespread public resistance to issue framings that foreground urgency-based claims in support of their objectives. Participants assessed energy initiatives with particular reference to temporality and urgency, and we argue these views raise justice concerns regarding distribution, the creation of environmental inequalities, public participation, and recognition. We also suggest a focus on urgency provides fresh perspectives on justice issues surrounding the speed and direction of technological development in general and of energy transitions in particular.

Abstract:
The extraction of oil and gas has increasingly shaped Canada’s economy and culture in recent years. As Canada attempts to move toward a low carbon economy, it is important to know how Canadians perceive the risks and opportunities associated with various energy sources. In particular, fracking, or hydraulic fracturing, is one such energy extraction technique that has received much media attention but little systematic research from social scientists in Canada. Drawing on survey data from a representative sample of citizens in a province that has utilized fracking extensively (British Columbia) and one that has placed a moratorium on its use (New Brunswick), this article examines public perceptions of the use of hydraulic fracturing. In particular, this paper explores the risks and opportunities people perceive from this technology in these different provincial energy contexts. The findings suggest that while New Brunswick residents saw more benefits and fewer risks from fracking than British Columbia residents, the variables shaping perceptions within each province were mostly similar. We argue that contemporary risk theorizing should more closely consider how people perceive opportunities associated with the use of this disruptive technology as well as how context shapes people’s perceptions.

Abstract:
High-quality water is essential for most industrial processes, and many of these processes generate large volumes of contaminated wastewater. Nanotechnology has the potential to make industrial water treatment more efficient and less expensive, though promising technologies must be demonstrated at higher scales to make a real impact.

Abstract:
Unconventional natural gas extraction via hydraulic fracturing coupled with horizontal drilling (HDHF) has generated disruptive growth in the domestic energy sector. Field analyses of residual HDHF fluids have detected halogenated species, potentially the product of unexplored reactions between authigenic halides and HDHF additives. Utilizing a custom high-pressure reactor system, we simultaneously screened 12 frequently disclosed, functionally diverse HDHF additives to uncover transformation chemistry. One emergent pathway, the halogenation of cinnamaldehyde in the presence of ammonium persulfate, demonstrated the potential for oxidative breakers to react with halides to yield reactive halogen species. Halogenated product formation, product distribution, and kinetics were evaluated with respect to shale well subsurface condition, linking transformation risk to measurable well-dependent characteristics (e.g., halide compositions, well temperatures, and pH). In a representative flowback brine, the brominated product dominated on a molar percent basis (6 ± 2%, as normalized by initial cinnamaldehyde loading) over chlorinated (1.4 ± 0.4%) and iodinated forms (2.5 ± 0.9%), reflecting relative halide abundance and propensity for oxidation. This work demonstrates that relevant subsurface reactions between natural brines and hydraulic fracturing additives can result in the unintended formation of halogenated products.

Abstract:
Water scarcity severely affects drylands threatening their food security, whereas, the oil and gas industry produces significant and increasing volumes of produced water that could be partly reused for agricultural irrigation in these regions. In this review, we summarise recent research and provide a broad overview of the potential for oil and gas produced water to irrigate food crops in drylands. The quality of produced water is often a limiting factor for the reuse in irrigation as it can lead to soil salinisation and sodification. Although the inappropriate use of produced water in irrigation could be damaging for the soil, the agricultural sector in dry areas is often prone to challenges in soil salinity. There is a lack of knowledge about the main environmental and economic conditions that could encourage or limit the development of irrigation with oil and gas effluents at the scale of drylands in the world. Cheaper treatment technologies in combination with farm-based salinity management techniques could make the reuse of produced water relevant to irrigate high value-crops in hyper-arid areas. This review paper approaches an aspect of the energy-water-food nexus: the opportunities and challenges behind the reuse of abundant oil and gas effluents for irrigation in hydrocarbon-rich but water-scarce and food-unsecured drylands.