Drill Pad Research Articles

Rehabilitation challenges for the onshore coal seam gas sector in Australia

The development of conventional oil and gas reserves followed by valorisation of coal seam gas (CSG) reserves in Queensland has seen the installation of over 16,000 wells. These wells are accompanied by thousands of kilometres of gathering lines, compression and water treatment facilities and transmission pipelines. The major rehabilitation challenges for the industry result less from technical challenges but rather from the sheer scale of the task. At present, the CSG industry continues to grow, and few of the CSG wells (other than exploration and appraisal wells) have yet reached the end of their life. The US experience presents a cautionary tale for adequate financial provisioning to mitigate the risks of orphaned wells. Secondly, the rehabilitation of multiple small parcels of land such as drill pads presents logistical challenges. Strategies to aggregate parcels for relinquishment will be required if the industry is to avoid thousands of individual land parcel evaluations at the time of relinquishment. These two rehabilitation challenges will be explored, risks for the industry and community assessed, and a call made for industry and government to work collaboratively to ensure an orderly and responsible rehabilitation program becomes an integral part of ongoing operations.

Mining exploration infrastructure affects biophysical habitat characteristics and ground-dwelling arthropod communities

Monitoring of environmental impacts of mining activities typically focuses on the main operation footprint, neglecting exploration infrastructure like tracks, roads, and drill pads. These areas are cleared of native vegetation and impacts on the surrounding environment can be both cumulative and enigmatic. Here, we study the impacts of mining exploration infrastructure on habitat characteristics and ground-dwelling arthropod communities in the Midwest region of Western Australia. The study was conducted at three mine sites, each with three infrastructure types: maintained tracks, unmaintained tracks, and drill pads along transects extending 100 m away from the disturbance into remnant vegetation. Habitat characteristics were measured, and arthropods collected from pitfall traps along these transects and identified using COI metabarcoding. The overall arthropod community and two indicator groups, ants (Formicidae) and springtails (Collembola) - were used to measure arthropod responses to changes in response to habitat disturbance. Whilst changes in habitat were only visible to 10 m from the disturbance, impacts on arthropod communities could be detected up to 100 m into the remnant vegetation, and these responses were more complex. In general, we found similar patterns expressed in the compositional changes for arthropods overall and between our chosen indicator groups, but they were not the same across all sites and infrastructure types. Our results demonstrate the utility of bulk arthropod metabarcoding and different arthropod indicator groups for documenting the effects of fine-scale habitat destruction, degradation, or disturbance. They also highlight the need to monitor the negative impacts of mineral exploration on the environment.

It Ain't Over Until We're Smoking Cigars on the Drill Pad: Poems From Standing Rock and the Frontlines by Mark Tilsen (review)

It Ain't Over Until We're Smoking Cigars on the Drill Pad: Poems From Standing Rock and the Frontlines by Mark Tilsen (review)

Mapping Abandoned Uranium Mine Features Using Worldview-3 Imagery in Portions of Karnes, Atascosa and Live Oak Counties, Texas

Worldview-3 (WV3) 16-band multispectral data were used to map exposed bedrock and mine waste piles associated with legacy open-pit mining of sandstone-hosted roll-front uranium deposits along the South Texas Coastal Plain. We used the “spectral hourglass” approach to extract spectral endmembers representative of these features from the image. This approach first requires calibrating the imagery to reflectance, then masking for vegetation, followed by spatial and spectral data reduction using a principal component analysis-based procedure that reduces noise and identifies homogeneous targets which are “pure” enough to be considered spectral endmembers. In this case, we used a single WV3 image which covered an ~11.5 km by ~19.5 km area of Karnes, Atascosa and Live Oak Counties, underlain by mined rocks from the Jackson Group and Catahoula Formation. Up to 58 spectral endmembers were identified using a further multi-dimensional class segregation method and were used as inputs for spectral angle mapper (SAM) classification. SAM classification resulted in the identification of at least 117 mine- and mine waste-related features, most of which were previously unknown. Class similarity was further evaluated, and the dominant minerals in each class were identified by comparison to spectral libraries and measured samples of actual Jackson Group uranium host rocks. Redundant classes were eliminated, and SAM was run a second time using a reduced set of 23 endmembers, which were found to map these same features as effectively as using the full 58 set of endmembers, but with significantly reduced noise and spectral outliers. Our classification results were validated by evaluating detailed scale mapping of three known mine sites (Esse-Spoonamore, Wright-McCrady and Garbysch-Thane) with published ground truth information about the vegetation cover, extent of erosion and exposure of waste pile materials and/or geologic information about host lithology and mineralization. Despite successful demonstration of the utility of WV3 data for inventorying mine features, additional landscape features such as bare agricultural fields and oil and gas drill pads were also identified. The elimination of such features will require combining the spectral classification maps presented in this study with high-quality topographic data. Also, the spectral endmembers identified during the course of this study could be useful for larger-scale mapping efforts using additional well-calibrated WV3 images beyond the coverage of our initial study area.

Anti-collision Analysis of Pad Drilling and Optimization of Wellbore Trajectory: A Field Case Study

Errors can occur in the wellbore position according to the fact the survey tools are not completely accurate; therefore, prediction of well path position is imperative for safe and cost-effective drilling operation. The aim of this paper is an analysis of collision avoidance as well as assessment and optimization of wellbore trajectory for minimizing the risk of collision by applying different anti-collision and planning techniques. Thus, anti-collision analysis of pad drilling in the Iraqi oil field has been investigated using Industry Steering Committee for Wellbore Survey Accuracy (ISCWSA) error model to estimate the wellbores position and assess their separation using different techniques available in the industry. Three actual offset wells X1, X2, X3, and one proposed principal X4 well in a drilling pad have been used in the collision avoidance model. Separation factor, ladder, and travel cylinder plots revealed a high possibility of X4 proposed well colliding with X3 actual offset well. The separation factor of 0.75 and 7.5 m center to center prove that the current design of X4 principal design doesn’t meet the anti-collision standards, accordingly, a design revision must be highly considered. The field operator hasn’t revised the well design due to the lack in the assessment of anti-collision risks, thus, the survey service company has advised the operator to modify the predetermined well trajectory due to major risk of collision with X3 offset well and the well has been sidetracked. After reviewing and optimizing the well trajectory by using slant and optimum align (curve hold curve) planning methods, the anti-collision results have been greatly improved. The results showed that, through adopting an adequate anti-collision risk assessment and the modified well design, problems associated with the execution of the improper well design could be totally eliminated.

Biological Soil Crusts of the Great Plains: A Review

Biological soil crusts (BSCs), or biocrusts, are composed of fungi, bacteria, algae, and bryophytes (mosses, etc.) that occupy bare soil, entwining soil particles with filaments or rootlike structures and/or gluing them together with polysaccharide exudates to form a consolidated surface crust that stabilizes the soil against erosion. BSCs are common in arid and semiarid regions where vascular plant cover is naturally sparse, maximizing the exposure of surface-dwelling organisms to direct sunlight. Although less prominent and less studied there, BSC organisms are also present in more mesic areas such as the Great Plains where they can be found in shortgrass and mixed-grass prairie, in the badlands of several states, where burrowing animals have created patches of bare soil, on damaged road-cuts, strip-mines, gas and oil drill pads, military training areas, heavily grazed areas, and burn scars. Even where BSCs are not readily visible to the naked eye, many of the organisms are still present. BSC organisms are passively dispersed to the Great Plains as airborne organismal fragments, asexual diaspores, or sexual spores that accompany wind-blown dust from as far away as northern China and Mongolia. BSCs can best be studied and managed by 1) acknowledging their presence; 2) documenting their diversity, abundance, and functional roles; and 3) minimizing unnecessary disturbance, particularly when the soils are dry. This paper describes the current knowledge of Great Plains BSCs in an effort to heighten awareness of these cryptic but crucial ecosystem components and to encourage new research initiatives to better understand and manage them in this biome. Some specific actions may include refined taxonomic and ecologic studies of BSC organisms in underexplored areas, particularly those previously less or not recognized as BSC habitat, and incorporation of techniques to sample airborne organisms.

Assessing the impacts of oil exploration and restoration on mammals in Murchison Falls Conservation Area, Uganda

AbstractGlobal energy demand has driven expansion of oil and gas extraction into African protected areas, raising concern about potential deleterious impacts on wildlife. Efforts aim to restore extraction sites to their original condition, but may take many years to be successful. We analysed the impact of human disturbance (road density, distance to border, sound levels and the presence of restored oil drill pads) on mammal distributions in Murchison Falls Conservation Area (MFCA), Uganda. We detected 27 mammal species using camera trap surveys within three disturbance‐related strata: restored (<500 m from a restored drill pad), disturbed matrix (within the disturbed landscape but >1 km from a disturbance feature) and remote (>3 km from any disturbance). Herbivore species richness was greater within the disturbed matrix and at restored sites compared to remote areas, whereas species richness did not vary by strata for other guilds. Occupancy models fit for 15 relatively common species indicated no difference in occupancy probability across the three strata, but giraffe occupancy was higher at sites with more restored drill pads. Most species did not avoid areas of high human disturbance in this study, and new vegetation growth may attract some herbivores to restored oil sites.

Rapid understory plant recovery following forest floor protection on temporary drilling pads

AbstractOil sands exploration fragments the boreal landscape by constructing numerous drilling pads to assess underground petroleum reserves. Reclamation of these pads is challenging and slow, particularly for forest understory species. We investigated the feasibility of accelerated forest understory restoration on these temporary pads by taking advantage of the propagule bank and clonal regeneration strategy of many boreal plants. We covered and protected the forest floor (FF) with subsoil during winter pad construction. This forest floor protection (FFP) method was then compared with the current practice of stripping off, stockpiling, and then replacing the FF during the reclamation phase (rollback, RB) and to conventional clearcut (CC) harvesting. In the first growing season, surface disturbance as well as richness and cover of plant regeneration was evaluated; vegetation assessment was repeated in the fifth growing season. Although there were some slight differences between the communities in the FFP and CC treatments, likely associated with varying levels of residual slash and subsoil material, there were striking differences between the communities in the RB and FFP treatments. In addition, while establishment of deciduous tree species was similar between the FFP and CC treatments, there were very few trees found in the RB treatment. The study indicates that protection and careful uncovering of the FF during temporary drilling pad construction should be a technique of choice for forest reclamation used in the boreal forest. However, as RB will still play a part in the reclamation of these sites, management intervention will be required to achieve reclamation goals.

Tomographic fracture imaging: Examples of induced fracture and reservoir-scale observations during wellbore stimulations, Niobrara and Bakken plays, USA

Classic microseismic techniques have been unable to adequately resolve many of the questions that have been asked with respect to reservoir stimulation and production in the Bakken and Niobrara unconventional resource plays as they have matured over the last few years. This has become evident especially in relation to the infill drilling and restimulation phases of field development. In support of efforts to design efficient continued development of operations in these areas, Whiting Oil and Gas has utilized a different, but related, technology to enhance understanding of the subsurface environment during and after reservoir stimulation treatments. We present two separate field examples of a novel reservoir monitoring technology that utilizes microseismic surface geophone arrays and seismic emission tomography (SET) methodologies to directly image both natural and hydraulically induced fracture systems. Tomographic fracture imaging (TFI) was developed with the goal of directly identifying and mapping active induced or natural fracture systems, as opposed to inferring them from a population of microseismic hypocenters as is done in classical microseismic data acquisition and analysis. Examples shown here consist of results from a purpose-designed array intended to monitor the stimulation efficiencies of three wellbores on a single Niobrara drill pad that was completed within a very short timeframe, and the results of a much larger reservoir-scale study showing the 4D reservoir effects of field production over a nine-month period by the TFI reprocessing of legacy microseismic data in the Bakken. These examples represent clear empirical evidence that the TFI technique is effective in detecting and localizing active fracture networks that are highly correlative to other wellbore data, even though much remains to be researched about the exact mechanisms involved in the generation of seismic energy within fracture networks.

Re-establishment of hummock topography promotes tree regeneration on highly disturbed moderate-rich fens

Winter exploration of oil sands deposits underlying wooded fens mostly eliminates the hummock-hollow topography on drilling pads and the ice roads leading to them, after their abandonment in spring. Recovery of black spruce (Picea mariana (P. Mill.) B.S.P.) and tamarack (Larix laricina (Du Roi) K. Koch) on these disturbed peatlands is thought to depend on the recovery of hummock topography. In late winter, numerous large blocks of frozen peat (1.5 × 1.5 m) were lifted out of the flattened drilling pads and positioned beside their excavated hollows; this was done on six temporary pads. Four years later, the condition of the mounds and the regeneration of conifers from natural seed dispersal were assessed on these elevated mounds compared to adjacent flattened areas of the pads. Then, conifer seedling density was more than five times higher on elevated spots than the mostly flat, flood-prone areas between them, and seedling density was positively related to mound height and strength of seed source. Higher mounds tended to have larger seedlings. Mounds on some of the pads were heavily eroded down; these pads had peat with higher humification, and operationally these pads were also treated in late winter when peat was thawing and fractured into pieces during mound construction. Developing a large volume of elevated substrate that persists until natural hummock-forming mosses can establish is thought necessary for tree recruitment and the recovery of the habitat for the threatened woodland caribou of this region.

Salting the Earth: The Environmental Impact of Oil and Gas Wastewater Spills.

Salting the Earth: The Environmental Impact of Oil and Gas Wastewater Spills.

Developing monitoring plans to detect spills related to natural gas production.

Surface water is at risk from Marcellus Shale operations because of chemical storage on drill pads during hydraulic fracturing operations, and the return of water high in total dissolved solids (up to 345g/L) from shale gas production. This research evaluated how two commercial, off-the-shelf water quality sensors responded to simulated surface water pollution events associated with Marcellus Shale development. First, peak concentrations of contaminants from typical spill events in monitored watersheds were estimated using regression techniques. Laboratory measurements were then conducted to determine how standard in-stream instrumentation that monitor conductivity, pH, temperature, and dissolved oxygen responded to three potential spill materials: ethylene glycol (corrosion inhibitor), drilling mud, and produced water. Solutions ranging from 0 to 50ppm of each spill material were assessed. Over this range, the specific conductivity increased on average by 19.9, 27.9, and 70μS/cm for drilling mud, ethylene glycol, and produced water, respectively. On average, minor changes in pH (0.5-0.8) and dissolved oxygen (0.13-0.23ppm) were observed. While continuous monitoring may be part of the strategy for detecting spills to surface water, these minor impacts to water quality highlight the difficulty in detecting spill events. When practical, sensors should be placed at the mouths of small watersheds where drilling activities or spill risks are present, as contaminant travel distance strongly affects concentrations in surface water systems.

Unconventional natural gas development and respiratory health

Unconventional natural gas development and respiratory health

Case Study Shows Benefits of Applying Hollow Glass Spheres to Drilling Fluids

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 174010, “Hollow-Glass-Sphere Application in Drilling Fluids: Case Study,” by Arminder Minhas, SPE, Halliburton; Brandon Friess, SPE, Farid Shirkavand, and Barry Hucik, Seven Generations Energy; Teresa Pena-Bastidas, 3M Canada; Bradley Ross, SPE, Halliburton; and Shawn Servinski and Frank Angyal, Seven Generations Energy, prepared for the 2015 SPE Western Regional Meeting, Garden Grove, California, USA, 27–30 April. The paper has not been peer reviewed. In an effort to optimize drilling operations and economics, an operator examined the effect of adding hollow glass spheres (HGSs) directly to the drilling fluid instead of performing underbalanced drilling. Both nitrogen and HGSs were believed to reduce hydrostatic pressure of the mud column in the hole, resulting in higher drilling rates of penetration (ROPs) and reduced mud losses to the wellbore. This paper provides information on HGSs as an economic alternative to nitrogen to help reduce the hydrostatic pressure of invert-emulsion drilling fluids. Introduction This case study focuses on the application of HGSs in two different sections of the drilling operation—a horizontal section and a vertical intermediate section. Data from a base-case horizontal section using an all-oil drilling fluid were compared with data of another well on the same drilling pad using the same fluid with the addition of HGSs. The intermediate-section data were from a base-case well that used an invert-emulsion drilling fluid, and they were compared with data from other intermediate well intervals in the same field that used an invert-emulsion drilling fluid with the addition of HGSs. Use of HGSs in Drilling Fluids HGSs are inert materials that are used as density-reducing agents. In the oil and gas industry, they are used for reducing the density of drilling fluids and cement blends. These hollow spheres (Fig. 1) are chemically inert, thermally stable (with a softening temperature of 600°C), and made of soda-lime borosilicate with a high strength/density ratio, and they can be added to both oil- and water-based fluids. A density reduction of up to 2.086 lbm/gal is possible when using HGSs. HGS addition helps reduce density and, consequently, the effective circulating density (ECD). Addition of HGSs to a lightweight drilling fluid allows consistent, stable properties and allows for measurement while drilling and controlled management of fluid properties. These lightweight fluids can be used for drilling at balanced, near-balanced, or underbalanced conditions. Applications include depleted reservoirs, geologically fractured formations, poorly consolidated formations, and high-permeability formations. In general, a reduction of differential pressure can result in the elimination of differential sticking, reduction or elimination of fluid loss, and mitigation of formation damage. This can result in higher productivity during drilling operations and during production.

Forest floor protection during drilling pad construction promotes resprouting of aspen

Drilling pads that are used to explore petroleum reserves in the boreal forest are often only used for a short time. We studied the vegetative regeneration potential of aspen (Populus tremuloides) through root suckers as a means to rapidly recover forest vegetation in these disturbed sites. We compared protecting the original forest floor under a layer of subsoil during the leveling of drilling pads, with the current practice of stripping off the forest floor and topsoil and placing it back on the site (Rollback) in the re-contouring of the reclamation phase. We also tested three techniques of delineating the forest floor so that it can be effectively uncovered during the reclamation phase. After re-contouring and top soil placement on the sites, we assessed the extent of surface disturbance, soil temperature, soil bulk density, and the density and height of aspen regeneration. Aspen suckers were tallest, had the highest density and had better survival when the forest floor was protected compared to the standard Rollback treatment. When protecting the forest floor, delineating the original forest floor from the subsoil cover resulted only in small differences in the aspen regeneration among delineation treatments with little impact on soil compaction and only moderate effects on soil surface disturbance. The study indicates that protection and the careful uncovering of the forest floor with or without using a delineation layer should be a preferred strategy for temporary drilling pad construction and their subsequent reclamation in aspen-dominated boreal forests.

Field Testing a New Rotary-Steerable-Drilling-Liner Technology

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 168044, ’First Field Testing of a New Rotary-Steerable-Drilling-Liner Technology on Alaska’s North Slope,’ by Greg Hobbs, Rob Stinson, and Chip Alvord, ConocoPhillips, and Okechukwu N. Anyanwu, Christian Klotz, and Muntasar Mohammad, Baker Hughes, prepared for the 2014 IADC/SPE Drilling Conference and Exhibition, Fort Worth, Texas, USA, 4-6 March. The paper has not been peer reviewed. Conventional drilling through lower intermediate intervals in the southern portion of the Alpine field on Alaska’s North Slope has posed significant challenges. While unstable shale sections can be drilled without significant issues, hole collapse has caused difficulties while tripping out of hole and running casings. In 2011, a new steerable-drilling-liner system was deployed in the field. This paper provides insights into the new technology and the field-trial program. Introduction The Alpine field, which came online in 2000, lies near the environmentally sensitive shoreline of the Arctic Ocean on the North Slope of Alaska (Fig. 1). It is the westernmost of the current North Slope producing fields and straddles the border of the National Petroleum Reserve— Alaska. The field was developed without a permanent road connection to the existing North Slope infrastructure, to address environmental and indigenous-community concerns. Much of the resupply effort for the roadless period is accomplished during the iceroad season. Field development has progressed from near-pad targets to higher-departure wells in a 6,700-ft-truevertical- depth reservoir section that has introduced drilling challenges. Background The development of the Alpine reservoir has progressed as an alternating horizontal-producer/-injector pattern for best recovery efficiency (Fig. 2). As field-pad development advanced southward, it was determined that a shale package had thickened in this direction. This thickening, compounded with progressively higher sail angles required to reach points at higher departures, led to issues that affected efficient running and cementing of intermediate liners. New techniques involving higher mud weights and managed-pressure drilling were attempted with limited success. The authors learned of a steerable-drilling- liner technology that was being developed and deployed offshore Norway to drill through and complete beyond troublesome hole sections. This system was researched, and a case was made to develop and deploy it in the Alpine field in Alaska. (For the details of the related feasibility study, please see the complete paper.) Deploying new technology in a remote, seasonally roadless Arctic development was no small commitment. Initial deployment plans used nonrotating torque reducers, premium liner connections to ensure integrity through multiple rotations in tortuous hole paths, robust solid centralizers proved in casing-drilling applications, and drilling-dynamics sensors placed above and below the liner to provide recorded and real-time data. A four-well, progressive, directionally complex pilot program was assigned by the resource asset for two reasons. First, it was not cost-effective to ship specialized equipment over ice roads for a single well project. Second, it was deemed important that the system be given a fair trial, because it could be a key to future development potential in the area. The technology could enable completion of high-departure wells in an unstable overburden where the environmental sensitivity of the area precludes the placement of more drilling pads.

Energy and Rangelands: A Perspective

On the Ground Depletion of conventional oil and natural gas reserves coupled to rising world demand for fossil fuels will have major impacts on US rangelands and ranches over the next 30 years. Shale oil and gas are unconventional fossil fuels now being aggressively developed on US rangelands. Their development involves a larger physical footprint in terms of roads, drill pads, mining pits, and water disposal ponds than conventional oil and gas development, but their development techniques are improving in terms of extraction efficiency and reduction of adverse environmental impacts. Groundwater contamination is the biggest potential threat to ranchers from shale oil and gas development. US ranchers will likely experience continued rising prices for their livestock due to world farmland loss, increased human population, and rising affluency in Asian countries, but their production costs will also rise due to higher energy costs. Implementing management practices involving risk aversion and minimization of...

Divergent Pathways of Successional Recovery for In Situ Oil Sands Exploration Drilling Pads on Wooded Moderate‐Rich Fens in Alberta, Canada

AbstractPeatlands in northern Alberta, Canada, are being rapidly impacted by oil sands activities, with potentially long‐term consequences for their recovery. In situ oil sands extraction requires exploration of oil resources on a dense network of drilling pads across the landscape. This study examined the recovery of wooded moderate‐rich (WMR) fens 10 years after abandonment of these sites with minimal restorative measures. Bryophyte and vascular plant diversity, site microtopography, and water chemistry were assessed on drilling pads and in adjacent areas of undisturbed reference habitat. WMR fens affected by drilling activities were divided a priori into two groups based on strongly divergent trends in their successional development. One group represented the majority of WMR fens observed on the land base; at these sites hummock‐forming mosses including minerotrophic Sphagnum species were infrequent and tree recruitment was almost absent. The other group was dominated by Sphagnum species, had Picea mariana and Larix laricina recruitment, and appeared to recover more quickly. Both groups had high abundance of wetland sedges, notably Carex aquatilis. Further, drilling pads belonging to the first group had a high water table, limited elevated microsites, and had surface flooding over a portion of the growing season, in contrast to Sphagnum‐dominated sites. Development of the aquatic, bryophyte‐poor wetland type is comparable to early stages of wetland succession and these systems will recover relatively slowly, likely from decades to more than a century. Restoring part of the vertical distribution of microhabitats before abandonment of these pads could stimulate the successional recovery of vegetation.

Fracturing Rocks to Unlock New Oil

This article discusses various uses and benefits of hydraulic fracturing technology in the field of oil industry. Engineers continue to increase hydraulic fracturing efficiency by developing better multistage stimulation systems. These systems enable treatment of many intervals along a horizontal wellbore with a minimum number of pull-outs, or even in a single continuous operation. Many key advances in drilling and hydrofracturing have resulted from sophisticated modeling programs. Mechanical engineers play key roles in many aspects of hydrofracturing, especially the design of better down-hole tools, new materials, and improved numerical models. With the advances in modeling and real-time measurement, operators can deliver just the right type of fracking pressure, exactly where they want it, and repeat the process as needed, either in the same well, one that parallels it, or one that radiates out from the same central drill pad. The experts feel that if the world wishes to fully use its oil-and-gas resources, it will go hand-in-hand with hydraulic fracturing.

Drawbacks to Natural Gas

E. Kintisch recently reported on the evolution of the climate stabilization wedge concept (“Climate study highlights wedge issue,” News & Analysis, 11 January, p. [128][1]), first conceptualized by Pacala and Socolow in 2004 ([ 1 ][2]). At the close of the News story, Socolow acknowledges the need for thoughtful assessment of the technological paths toward carbon neutrality, but not before he touts the recent expansion of natural gas as “a rare sign of progress.” Natural gas is increasingly held up as a clean-burning, domestic “bridge fuel” paving the way toward energy independence. The problem with this assertion is that the recent proliferation of U.S. natural gas production is largely due to the expansion of hydraulic fracturing methodology to access shale gas ([ 2 ][3]). Once extracted, natural gas burns cleaner than coal or oil; however, the extraction-to-consumer carbon footprint of hydraulically fractured natural gas is greater than that of traditional energy sources ([ 3 ][4]). Moreover, hydraulic fracturing is increasingly linked with potentially irremediable freshwater contamination. In Pavillion, Wyoming, for instance, toxic or carcinogenic compounds added to fracking fluid have been found in drinking wells adjacent to drill pads ([ 4 ][5]). As we grapple with how to meet society's energy demands while obtaining carbon neutrality, we cannot pay for carbon offsets at the expense of other valuable natural resources, such as fresh water. ![Figure][1] Shale gas well site. CREDIT: DWIGHT NADIG/ISTOCKPHOTO 1. [↵][6]1. S. Pacala, 2. R. Socolow , Science 305, 968 (2004). [OpenUrl][7][Abstract/FREE Full Text][8] 2. [↵][9]Energy Information Administration, “Annual energy outlook” (U.S. Department of Energy, Washington, DC, 2011). 3. [↵][10]1. R. W. Howarth, 2. R. Santoro, 3. A. Ingraffea , Clim. Change 106, 679 (2011). [OpenUrl][11][CrossRef][12][Web of Science][13] 4. [↵][14]1. D. C. DiGiulio, 2. R. T. Wilkin, 3. C. Miller, 4. G. Oberly , “Draft: Investigation of ground water contamination near Pavillion, Wyoming” (EPA, Office of Research and Development, Ada, OK, 2011); [www.epa.gov/region8/superfund/wy/pavillion/EPA\_ReportOnPavillion\_Dec-8-2011.pdf][15]. [1]: pending:yes [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #ref-4 [6]: #xref-ref-1-1 View reference 1 in text [7]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DPacala%26rft.auinit1%253DS.%26rft.volume%253D305%26rft.issue%253D5686%26rft.spage%253D968%26rft.epage%253D972%26rft.atitle%253DStabilization%2BWedges%253A%2BSolving%2Bthe%2BClimate%2BProblem%2Bfor%2Bthe%2BNext%2B50%2BYears%2Bwith%2BCurrent%2BTechnologies%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.1100103%26rft_id%253Dinfo%253Apmid%252F15310891%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [8]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjEyOiIzMDUvNTY4Ni85NjgiO3M6NDoiYXRvbSI7czoyNDoiL3NjaS8zNDAvNjEyOS8xNDEuMS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30= [9]: #xref-ref-2-1 View reference 2 in text [10]: #xref-ref-3-1 View reference 3 in text [11]: {openurl}?query=rft.jtitle%253DClim.%2BChange%26rft.volume%253D106%26rft.spage%253D679%26rft_id%253Dinfo%253Adoi%252F10.1007%252Fs10584-011-0061-5%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [12]: /lookup/external-ref?access_num=10.1007/s10584-011-0061-5&link_type=DOI [13]: /lookup/external-ref?access_num=000290449200010&link_type=ISI [14]: #xref-ref-4-1 View reference 4 in text [15]: http://www.epa.gov/region8/superfund/wy/pavillion/EPA_ReportOnPavillion_Dec-8-2011.pdf