Unconventional Natural Gas Extraction Research Articles

Investigation of the impact of heating and liquid nitrogen (LN2) cooling on the mechanical and acoustic emission (AE) properties of coal

Liquid nitrogen has emerged as a promising fracturing medium for unconventional natural gas extraction, particularly in the context of coalbed methane extraction, generating significant interest in recent times. In this paper, we analyze the acoustic emission (AE) characteristics of coal samples treated with liquid nitrogen under three-point bending load conditions using indoor experiments and field investigations. We investigate the impact of liquid nitrogen on coal samples by analyzing AE data. The mechanical properties of coal samples with varying initial temperatures were tested under three-point bending load conditions after treatment with liquid nitrogen. The load-displacement curve was analyzed to study the mechanical properties of the coal samples after treatment with liquid nitrogen. Through indoor three-point bending experiments, data analysis, and knowledge of mechanics, we systematically investigated the changes in mechanical properties caused by liquid nitrogen treatment under different conditions. The results demonstrate that the application of liquid nitrogen has significant impacts on the mechanical and AE characteristics of coal samples. The load-displacement curve indicated that the mechanical properties of the coal samples changed after treatment with liquid nitrogen. The AE experiment revealed regular changes in vibration and energy parameters of coal samples after liquid nitrogen treatment under different conditions. We further investigated the changes in mechanical properties and deformation characteristics of coal samples after undergoing liquid nitrogen freezing and thawing in differing environments. Graphs such as load-displacement curves, load-time curves, cumulative vibration count-energy count graphs, and RA-AF density distribution diagrams visually demonstrated the changes in mechanical properties and deformation characteristics. Through an integrated approach of indoor experiments, data analysis, and knowledge of mechanics, our study provides a better understanding of the behavior of coal samples under different conditions. This understanding can contribute to the development of safer and more efficient methods for extracting coalbed methane.

Employment and Income Effects of Investments Made Using the Act 13 Unconventional Natural Gas Impact Fee in Pennsylvania

Unconventional natural gas extraction presents numerous opportunities and risks for communities across the United States. To capture a portion of the revenue generated by the resource states tax unconventional natural gas development. While most states collect revenue via severance taxes, Pennsylvania took a novel approach and established an impact fee on the industry instead. Unlike severance taxes in other states, the fee is collected annually and distributed directly to municipalities. While reports show that municipalities use the funds to pay for critical infrastructure, no best practices on how to allocate the funds exist. Citing the literature on mineral resource extraction and infrastructure-led development in American communities, this study examined impact fee payments made to counties with unconventional natural gas wells. The study evaluated whether counties that used the funds to invest in infrastructure were better off in terms of employment and income than other shale-producing counties that did not. Panel fixed- and random-effects regressions suggested that no statistically significant employment or income effects existed. The results suggest that local infrastructural investments are not a successful way to overcome the resource curse issues identified in the literature.

Quantitative characterization of the pore volume fractal dimensions for three kinds of liquid nitrogen frozen coal and its enlightenment to coalbed methane exploitation

Liquid nitrogen fracturing technology is an important means to improve the permeability of coal seams and realize unconventional natural gas extraction. In order to study the fractal characteristics of pore structure of coal frozen by liquid nitrogen, the pores of both nonfrozen and frozen samples of lignite, bituminous coal, and anthracite were measured with a high-pressure adsorption meter, a mercury porosimeter, and a low-field nuclear magnetic resonance (NMR). The test results showed that after freezing in liquid nitrogen, the pores of coal were effectively expanded. Among them, Nitrogen adsorption of lignite, bituminous coal and anthracite increased by 20.82%, 6.54% and 20.39%. The conversion rates from adsorption pore to seepage pore were 2.16%, 0.78% and 3.57%. The research results of pore fractal dimension showed that the multifractal characteristics of macropores were higher than that of mesopores and micropores. After liquid nitrogen freezing, the pore fractal dimension of lignite, bituminous coal and anthracite decreased by 0.031, 0.009 and 0.003, and the pore structure tends to be smooth. It showed the liquid nitrogen freezing coal enhances the migration and drainage of coalbed methane, which has reference significance for the further research of liquid nitrogen fracturing technology.

Research on Seepage Characteristics of Y-Shaped Fractures under Different Fracture Roughness

Fractures are widely distributed in coal, and studying the seepage characteristics of fluids in fractures is of great significance for unconventional natural gas extraction and prevention of gas disasters. In this work, based on the W-M fractal function, a Y-shaped fracture model with different roughness is established. The seepage characteristics of Y-shaped fracture with different roughness are interpreted from two perspectives. Firstly, the seepage law of the Y-shaped fracture with the same roughness is studied. Secondly, the fluid competitive diversion capacity caused by the difference of branch fracture roughness is discussed. The results show that the fracture roughness is an important factor affecting the seepage characteristics of the fracture. When the roughness of the fracture is identical, the outlet flow rate, velocity, and Re are all positively correlated with pressure, and the flow regime is unchanged. The increase in the fracture roughness will lead to a significant flow rate and momentum loss, resulting in maximum loss up to 45.44%, besides, enhance the flow resistance of the fracture, Re increasing by 771, 713, 489, and 355, respectively, at four patterns. And there is a threshold DM between 1.1 and 1.2 so that the major influencing factor on hydraulic conductivity changes. In addition, the roughness difference between the branch fractures of the Y-shaped fracture is the key factor to control the fluid competitive diversion capacity. The larger the roughness difference, the greater difference in flow velocity, and the more significant change in flow rate proportion, which proportion differs by 4%, 44%, and 54%, respectively, and the stronger smooth branch fracture competitive diversion capacity, and the lower the rough branch fracture hydraulic conductivity. As the inlet pressure increases, the two branch fractures Re gradually increases but Eu decreases, which Eu in smooth branch fracture is smaller is 15, 19, 20, and 21 smaller than that of rough branch, respectively, and the rough branch fracture competitive diversion capacity is weakened. Both roughness difference and inlet pressure will affect the competitive diversion capacity of the Y-shaped fracture. These results are expected to provide new insights for the exploitation of underground fluid resources.

The Influence of Confining Stresses on Formation Kinetics of Methane Gas Hydrates

Unconventional natural gas extraction has undergone rapid progress in recent years as an emerging energy source, and the amount of methane gas stored in gas hydrates is estimated to be larger than that of all other natural gas resources combined. In the process of finding suitable hydrate reservoirs for possible exploitation and other applications, it is vital to understand the effect of reservoir conditions on the formation kinetics of methane gas hydrates. The aim of this study is to investigate hydrate formation characteristics in a porous medium under different confining conditions, focusing on the effect of confining pressure on hydrate nucleation, growth, and saturation. A series of experiments was performed to simulate in-situ hydrate reservoir conditions in a custom-designed reactor to synthesise methane hydrates in a porous quartz sand medium under different confining and formation pressures. Temporal changes in gas pressure and temperature were incorporated to quantify the conversion of methane and water into gas hydrates. The results substantiate the extremely random nature of hydrate formation. Formation behaviour in the intermediate stages was observed to be highly individualistic due to the pore-scale configuration of hydrates. The pressure decrease observed during hydrate formation has a direct relationship with the timely progression of hydrate saturation. Moreover, the resultant hydrate saturation at the completion of the formation increases with confining pressure, while the initial formation pressure of methane gas also has a positive correlation with final hydrate saturation. Higher effective stress conditions on the porous medium contribute to greater hydrate saturation within the pores. 40% and 70% increments of effective stress cause the final hydrate saturation to be raised by 20 % and 30 %, respectively, complementing field observations where higher hydrate saturations were detected at the lowermost layers of the hydrate stability zone.

Numerical Simulation of Pressure Distribution Changes in Porous Rocks under the Action of High Pressure Fluid

The rock medium has the characteristics of heterogeneity, opacity and porosity. Fluid injection (such as hydraulic fracturing technology) can make the tight rock mass form a gas permeability enhancement zone near the borehole, which is conducive to unconventional natural gas extraction. Compared with experimental research, numerical simulation research has lower cost and higher efficiency, and has become an important method for research on fluid interaction and pore pressure. Based on this, this article mainly conducts a numerical simulation study on the changes in the internal pressure distribution of porous rocks under the action of high-pressure fluid (HPF). This article outlines the mechanism of quasi-static HPF fracturing coal and rock, and describes the classification of tensile fracture and shear fracture. In this paper, a numerical simulation method is used to construct a model of a porous rock sample, and a test of the internal pressure of the porous rock under the action of a HPF is carried out on the rock simulation sample. The experiment shows that when the intermediate principal stress σ2 is 20 MPa, the peak pressure of fluid is 12.5 MPa; when σ 2 is 25 MPa, the peak fluid pressure of is 12 MPa. This shows that the intermediate principal stress (or horizontal stress difference) is negatively related to the maximum fluid pressure.

Research on Seepage Characteristics of Y-Shaped Fractures Under Different Fracture Roughness

Fractures are widely distributed in coal, and studying the seepage characteristics of fluids in Y-shaped fractures is of great significance for unconventional natural gas extraction and prevention of gas disasters. In this paper, based on the W-M fractal function, a Y-shaped fracture model with different roughness is established. The different seepage characteristics caused by rough morphology characteristics and roughness difference of the Y-shaped fracture is systematically studied, and the influence of fracture roughness on fracture seepage characteristics and fracture roughness difference on fracture fluid competitive diversion capacity are discussed. The results show that the fracture roughness is an important factor affecting the seepage characteristics of the fracture. When the fractal dimension of the fracture is identical, the outlet flow rate, velocity and Re all increase with the increase of the inlet pressure, and the flow regime is unchanged. The increase in the fracture roughness will lead to significant momentum loss and enhance the flow resistance of the fracture. In addition, the roughness difference between the branch fractures of the Y-shaped fracture is the key factor to control the fluid competitive diversion phenomenon. The larger the roughness difference between the two branch fractures, the greater difference in flow velocity, and the more significant change in flow rate proportion. As the inlet pressure increases, the two branch fractures Re gradually increases and Eu decreases, which smooth branch fracture Re grows faster, its Eu is much smaller than rough branch fracture Eu, and the smooth branch fracture competitive diversion capacity is enhanced. These results can provide new insights for the exploitation of underground fluid resources.

Quantifying source contributions of volatile organic compounds under hydraulic fracking moratorium

Volatile organic compounds (VOCs) are precursors for ozone (O3) and secondary particulate matter, which contribute to asthma and cardiovascular diseases. With the technology development of hydraulic fracking, the United States experienced a shale gas boom in the last decade while the public raised concerns about the potential health impacts of co-emitted VOCs and other airborne pollutants. National Energy Technology Laboratory conducted stationary trailer-based ambient monitoring to study the sources of VOCs in Maryland, where the state enacted a moratorium on unconventional natural gas extraction. The campaign had two periods, May to August 2014 (summer) and November 2014 to February 2015 (winter). Ethane was the most abundant VOC, averaging 12.3 ppb (SD = 15.7 ppb) in summer and 21.7 ppb (SD = 21.6 ppb) in winter. The seasonal variation of VOCs indicated different source strengths. The sampling region was in the nitrogen oxides (NOx) limited regime for O3 production, and the O3 concentrations were sensitive to VOC/NOx ratios in the early mornings. We derived a six-factor profile using positive matrix factorization: motor vehicles, industrial, biogenics, coal burning, fugitive and evaporative, and ozone secondary. The fugitive and evaporative factor explained 44.5% of total VOCs, and the motor vehicles factor followed second with 15.5%. Oil and gas activities had a considerable impact on the abundance of VOCs in this region.

Quantifying atmospheric reactive nitrogen concentrations, dry deposition, and isotope dynamics surrounding a Marcellus Shale well pad

Unconventional natural gas (UNG) extraction activities have become important contributors to regional NOx emissions inventories. Currently, there is a knowledge gap in the amount of total N deposition surrounding well pads undergoing UNG extraction despite the fact that some areas with extensive natural gas extraction activity are already in exceedance of nitrogen critical loads. In this study, we measured the magnitude of total dry N deposition from NO2, HNO3, and NH3 attributable to the development of two UNG wells at a Marcellus Shale well pad study site. This study documents concentrations, deposition fluxes, and isotope values of NO2, HNO3, O3, and NH3 up- and down-wind along a 750-m well pad passive sampling transect across a 16-acre well pad containing two unconventional wells during all phases of development and extraction comprising fifteen distinct sampling periods. An access road transect was also utilized to explore reactive N dynamics in a near-road environment on the well pad where NO2 concentration and isotope dynamics were highly correlated with daily traffic count (r2 = 0.78–0.88, p < 0.01). An onsite chemiluminescent NO2 source apportionment model was compared against δ15N–NO2 and δ18O–NO2 source apportionment models (r2 = 0.57 and 0.82 respectively), demonstrating the possible utility of δ18O–NO2 as a source apportionment tool in near-source environments. In addition, the δ15N–NO2 source apportionment method compared well against a background-subtraction method (slope = 0.82, r2 = 0.88, p < 0.001) during non-wintertime conditions and was used to find N loadings directly attributable to well pad activities. In total, the total N deposition across the transect, attributable to well pad activities, utilizing industry's best management practices, ranged from 0.16 to 0.55 kg N ha−1 yr−1. This magnitude of well pad attributable N deposition is high enough to result in exceedances of nitrogen critical loads in areas with high well count densities and high baseline N deposition.

Determining conventional and unconventional oil and gas well brines in natural samples I: Anion analysis with ion chromatography

Unconventional natural gas extraction by hydraulic fracturing requires millions of gallons of water and generates flowback water, produced water and recycled fluids of varying chemical composition. Ion chromatography (IC) is a relatively low cost and efficient means to determine the anionic composition, however, the wide range in anionic content of these fluids poses a challenge to analytical methods developed for “natural” waters. We report here that the combination of UV and conductivity detectors increased detection sensitivity (e.g., 10–50 ppb) and expanded the number of anions detectable in a single sample run. Samples from four unconventional shale gas wells, two impoundments, nine conventional oil wells, two freshwater streams and mine drainage samples were analyzed in this study. All produced water samples and impoundment samples had high chloride (17,500–103,000 mg L−1, 93,900 to 134,000 mg L−1, 27,700 and 30,700 mg L−1), bromide (178–996 mg L−1, 183–439 mg L−1, 230 and 260 mg L−1) and conductivity (38,500–160,000 μS/cm3, 95,300 to 183,000 μS/cm3, 61,500 and 103,000 μS/cm3), respectively, relative to mine drainage and freshwater stream samples. Molar ratio analysis using Cl−/Br− to Cl− and SO42−/Cl− to Br− revealed significant differences between the samples, providing a simple means for distinguishing water impacted by different sources of contamination.

Effective CH4 enrichment from N2 by SIM-1 via a strong adsorption potential SOD cage

Methane enrichment from nitrogen is a necessary means for low-quality unconventional natural gas (coal mine methane) extraction, where adsorption-separation technology has become a research hotspot due to its low energy consumption and cost-effectiveness. In this work, three SOD-type ZIFs (ZIF-8, ZIF-90 and SIM-1, the latter also known as ZIF-94) are taken as methane sorbents for CH4/N2 separation. The experimental results show that SIM-1 (ZIF-94) has the highest CH4 adsorption capacity (1.5 mmol/g, 298 K and 1 bar) and adsorption heat (23.9 kJ/mol), although its surface area is the lowest (597 m2/g). No other known ZIF material has a higher CH4 adsorption capacity than SIM-1(ZIF-94), although some rare MOF and other porous materials can achieve such a high value. By comparing its CH4 adsorption capacity and BET surface with ZIF-93 (RHO type), which has the same units as Zn-almeIm, SIM-1(ZIF-94) has a high adsorption capacity of CH4 due to its suitable SOD cage size (0.84 nm) acting as a strong adsorption potential. Indeed, excellent enrichment–separation of the CH4/N2 mixture (30:70 and 50:50, v/v) with a high adsorption selectivity of 7.0 (IAST) rarely occurs for sorbents at room temperature and ambient pressure. Both the experimental and simulated data of the gas mixtures indicate that SIM-1 (ZIF-94) has excellent capability for enriching and removing nitrogen from methane, and it shows extraordinary industrial value.

Surface water and groundwater analysis using aryl hydrocarbon and endocrine receptor biological assays and liquid chromatography-high resolution mass spectrometry in Susquehanna County, PA.

The contamination of surface water and ground water by human activities, such as fossil fuel extraction and agriculture, can be difficult to assess due to incomplete knowledge of the chemicals and chemistry involved. This is particularly true for the potential contamination of drinking water by nearby extraction of oil and/or gas from wells completed by hydraulic fracturing. A case that has attracted considerable attention is unconventional natural gas extraction in Susquehanna County, Pennsylvania, particularly around Dimock, Pennsylvania. We analyzed surface water and groundwater samples collected throughout Susquehanna County with complementary biological assays and high-resolution mass spectrometry. We found that Ah receptor activity was associated with proximity to impaired gas wells. We also identified certain chemicals, including disclosed hydraulic fracturing fluid additives, in samples that were either in close proximity to impaired gas wells or that exhibited a biological effect. In addition to correlations with drilling activity, the biological assays and high-resolution mass spectrometry detected substances that arose from other anthropogenic sources. Our complementary approach provides a more comprehensive picture of water quality by considering both biological effects and a broad screening for chemical contaminants.

Halogenation Chemistry of Hydraulic Fracturing Additives under Highly Saline Simulated Subsurface Conditions.

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.

MALDI-TOF MS for the Identification of Cultivable Organic-Degrading Bacteria in Contaminated Groundwater near Unconventional Natural Gas Extraction Sites.

Groundwater quality and quantity is of extreme importance as it is a source of drinking water in the United States. One major concern has emerged due to the possible contamination of groundwater from unconventional oil and natural gas extraction activities. Recent studies have been performed to understand if these activities are causing groundwater contamination, particularly with respect to exogenous hydrocarbons and volatile organic compounds. The impact of contaminants on microbial ecology is an area to be explored as alternatives for water treatment are necessary. In this work, we identified cultivable organic-degrading bacteria in groundwater in close proximity to unconventional natural gas extraction. Pseudomonas stutzeri and Acinetobacter haemolyticus were identified using matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF MS), which proved to be a simple, fast, and reliable method. Additionally, the potential use of the identified bacteria in water and/or wastewater bioremediation was studied by determining the ability of these microorganisms to degrade toluene and chloroform. In fact, these bacteria can be potentially applied for in situ bioremediation of contaminated water and wastewater treatment, as they were able to degrade both compounds.

Coping with change in rural landscapes: The psychological stress of rural residents experiencing unconventional gas developments

Rural landscapes in many parts of the world are experiencing increasing pressure from competing uses. One particular use, unconventional natural gas extraction, has received considerable attention over the past decade owing to its rapid growth and associated impacts on rural landscapes. This study examined how a sample of Australian rural residents experienced the processes of psychological stress induced by a coal seam gas project that created perceived undesirable changes to resources they valued. Its effect on residents’ psychological well-being slowly unfolded over several years. We deconstructed the stress processes by investigating primary appraisal, secondary appraisal, and subsequent emotional and coping responses guided by the cognitive theory of stress and coping. Primary appraisal measured how the impacts of change on personal and communal resources were assessed while secondary appraisal gauged the options available to individuals to cope. Our results show that when primary appraisal alerts individuals of resource loss, negative emotions are more likely experienced. Such an appraisal directly drives engagement in eight coping strategies classified into four categories: problem-focused, support-based, emotion-focused, and maladaptive coping. It also motivates coping indirectly except for one strategy of emotion-focused coping mediated by negative emotions. While secondary appraisal also directly contributes to four coping strategies that each pertains to one of the four coping categories, it has no effect on negative emotions and four remaining coping strategies that are emotion-focused and maladaptive. These findings shed light on our understanding of the psychological consequences of undesirable change of land use on rural communities. Implications for land use policy are discussed with an emphasis on the need for considering a holistic perspective on the multi-dimensional nature of rural resources valued by community residents and establishing procedural fairness and legitimacy for proposed changes.

Allocating Damage Compensation in a Federalist System: Lessons from Spatially Resolved Air Emissions in the Marcellus.

The benefits and impacts of unconventional natural gas development are realized at different spatial scales, calling into question the appropriate jurisdictional level at which to set and enforce environmental policy. This paper evaluates impact fee allocation under Pennsylvania Act 13, which authorizes Commonwealth payments to Pennsylvania counties to offset damages from unconventional natural gas extraction in exchange for consolidated state-level regulatory authority. We evaluate the adequacy of damage compensation allocation for impacts that are spatially and temporally removed from the well site, using the air emissions associated with natural gas wastewater transport as a case study. Wastewater transport from wells eligible for 2011 impact fee disbursement calculations generated an estimated $11.6 million in air emission damages from 2004 to 2013, with 35% of damages occurring out-of-state and an average of 94% of damages occurring out-of-county. We find that compensatory payments from Pennsylvania Act 13, which are based upon the number of wells drilled in a county in a single year, inadequately account for spatially and temporally distributed impacts from wastewater transport. This case study of Pennsylvania Act 13 highlights potential issues associated with central regulators using compensatory payments as a means of resolving jurisdictional conflict. In cases where the central regulator benefits from the polluting activity, we argue that there is incentive to focus compensation on local damages and undervalue regional and spatially distributed damages in compensation algorithms.

The Influence of Marcellus Shale Extraction Emissions on Regionally Monitored Dry Reactive Nitrogen Deposition

Emissions of nitrogen oxides (NOx) in the United States (U.S.) from large stationary sources, such as electric generating units, have decreased since 1995, driving decreases in nitrogen deposition. However, increasing NOx emissions from emerging industries, such as unconventional natural gas (UNG) extraction, could offset stationary source emission reductions in shale gas producing regions of the U.S. The Marcellus Shale in the northeastern U.S. has seen dramatic increases in the number of wells and associated natural gas production during the past 10 years. In this study, we examine the potential impacts of shale gas development on regional NOx emission inventories and dry deposition fluxes to Clean Air Status and Trends (CASTNET) sites in Pennsylvania and New York. Our results demonstrate that the current distribution of CASTNET sites is ineffective for monitoring the influence of Marcellus well NOx emissions on regional nitrogen deposition. Despite the fact that existing CASTNET sites are not influenced by UNG extraction activity, NOx emissions densities from shale gas extraction are substantial and are estimated to reach up to 21 kg NOx ha-1 year-1 in some regions. If these emissions deposit locally, UNG extraction activity could contribute to critical nitrogen load exceedances in areas of high well density.

Trophy Hunting vs. Manufacturing Energy: The Price-Responsiveness of Shale Gas

We analyze the relative price elasticity of unconventional versus conventional natural gas extraction. We separately analyze three key stages of gas production: drilling wells, completing wells, and producing natural gas from the completed wells. We find that the important margin is drilling investment, and neither production from existing wells nor completion times respond strongly to prices. We estimate a long-run drilling elasticity of 0.7 for both conventional and unconventional sources. Nonetheless, because unconventional wells produce on average 2.7 times more gas per well than conventional ones, the long-run price responsiveness of supply is almost 3 times larger for unconventional compared to conventional gas.Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Trophy Hunting versus Manufacturing Energy: The Price Responsiveness of Shale Gas

AbstractWe analyze the relative price responsiveness of unconventional versus conventional natural gas extraction. We separately analyze three key stages of gas production: drilling wells, completi...

The cost of unconventional gas extraction: A hedonic analysis

We focus on identification and estimation of potentially negative environmental impacts of unconventional natural gas extraction on property values in the United States and advance previous research by contributing new data and new identification strategies for isolating these potential impacts. Our study area consists of two counties in Pennsylvania that are home to large amounts of unconventional natural gas extraction but are otherwise isolated from other resource extraction industries or large urban areas. We deploy parametric, semi-parametric, and matching hedonic regression models that include recent quasi-experimental methods and, in contrast to previous research and much popular intuition, we fail to find robust significance that negative environmental externalities of natural gas extraction are manifested in nearby property values. While there may be plausible risks associated with unconventional natural gas extraction, we do not find consistent evidence to suggest that these risks significantly affect nearby property values.