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| Although public discussion and awareness of hydraulic fracturing processes have become widespread in the past several years, the technique has been used for decades. Improvements in technology and implementation practices have helped it to become an essential process for the development of unconventional resources, such as shale gas and shale oil, which continue to transform U.S. energy production. Hydraulic fracturing has been cited as a key technology that has now made the U.S. the world’s largest global oil producer. | | Although public discussion and awareness of hydraulic fracturing processes have become widespread in the past several years, the technique has been used for decades. Improvements in technology and implementation practices have helped it to become an essential process for the development of unconventional resources, such as shale gas and shale oil, which continue to transform U.S. energy production. Hydraulic fracturing has been cited as a key technology that has now made the U.S. the world’s largest global oil producer. |
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− | “Hydraulic fracturing” is a general term for the technique used to “fracture” rock in an oil or gas reservoir by pumping water (or other fluid) and sand (or other granular material) into a sedimentary rock layer at a pressure that is greater than the earth’s natural pressure at that depth. The oil or natural gas that producers are looking to extract consists of hydrocarbon molecules trapped in the tiny spaces between the grains of sand or tiny clay particles that comprise the rock. By creating artificial cracks in the rock through hydraulic fracturing, these molecules are able to flow out along these cracks to the well, where they are brought to the surface. In nature, there is much more hydrocarbon in the rock than historically has been produced. Hydraulic fracturing as a technology provides a more efficient method of producing the additional oil and gas. | + | “Hydraulic fracturing” is a general term for the technique used to “[[fracture]]” rock in an oil or gas reservoir by pumping water (or other fluid) and sand (or other granular material) into a sedimentary rock layer at a pressure that is greater than the earth’s natural pressure at that depth. The oil or natural gas that producers are looking to extract consists of hydrocarbon molecules trapped in the tiny spaces between the grains of sand or tiny clay particles that comprise the rock. By creating artificial cracks in the rock through hydraulic fracturing, these molecules are able to flow out along these cracks to the well, where they are brought to the surface. In nature, there is much more hydrocarbon in the rock than historically has been produced. Hydraulic fracturing as a technology provides a more efficient method of producing the additional oil and gas. |
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| Strategies similar to what we today would call hydraulic fracturing were first used to increase fluid flow in oil and water wells as early as the 1860s, although the first experiment with modern hydraulic fracturing techniques occurred in 1947, by Stanolind Oil and Gas Corp., at the Hugoton gas field in Grant County, Kansas. | | Strategies similar to what we today would call hydraulic fracturing were first used to increase fluid flow in oil and water wells as early as the 1860s, although the first experiment with modern hydraulic fracturing techniques occurred in 1947, by Stanolind Oil and Gas Corp., at the Hugoton gas field in Grant County, Kansas. |
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| The technology is essentially the same for offshore wells, accomplished with boats and equipment modules that can be placed on the drill ship or offshore platform. | | The technology is essentially the same for offshore wells, accomplished with boats and equipment modules that can be placed on the drill ship or offshore platform. |
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− | A hydraulic stimulation project must have all of this equipment linked together to be able to push a slurry of water and sand down a narrow pipe to a depth of one to two miles – and then along a lateral pipe to a distance of possibly more than a mile and a half. The pumps must overcome not only the friction of the water in the pipe, but also the natural pressure of the geologic formation at depth. Thus, many pumps working together are necessary to both overcome friction and squeeze the water and sand mixture into the fractures. | + | A hydraulic stimulation project must have all of this equipment linked together to be able to push a slurry of water and sand down a narrow pipe to a depth of one to two miles – and then along a [[lateral]] pipe to a distance of possibly more than a mile and a half. The pumps must overcome not only the friction of the water in the pipe, but also the natural pressure of the geologic formation at depth. Thus, many pumps working together are necessary to both overcome friction and squeeze the water and sand mixture into the fractures. |
| The horizontal part of the well is stimulated in multiple sections. The stimulation of each section takes a few hours and the entire hydraulic fracturing operation will be spread over two to five days. | | The horizontal part of the well is stimulated in multiple sections. The stimulation of each section takes a few hours and the entire hydraulic fracturing operation will be spread over two to five days. |
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| Different types of rocks have different physical properties and contain different fluids: oil, natural gas and water. The location, size and design of the rock’s existing fractures, density and variations in subsurface pressures also affect the hydraulic fracturing operation, so all of these factors must be considered for every type of rock that will be hydraulically stimulated. | | Different types of rocks have different physical properties and contain different fluids: oil, natural gas and water. The location, size and design of the rock’s existing fractures, density and variations in subsurface pressures also affect the hydraulic fracturing operation, so all of these factors must be considered for every type of rock that will be hydraulically stimulated. |
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− | For most oil and gas wells, the force of gravity on the rock generally determines the vertical pressure at any depth. Vertical pressure on the rock increases as you go deeper, just as water pressure increases as you go deeper in the ocean. | + | For most oil and gas wells, the force of [[gravity]] on the rock generally determines the vertical pressure at any depth. Vertical pressure on the rock increases as you go deeper, just as water pressure increases as you go deeper in the ocean. |
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| An additional complication is that rocks are deposited in basins and are not all horizontal – and they are pushed as the continents shift. The vertical pressure always generates the largest stress on a rock; the horizontal stresses on a rock will control the lateral spreading of the hydraulic fractures. Fractures tend to form in the direction of the least stress, which is generally horizontal. | | An additional complication is that rocks are deposited in basins and are not all horizontal – and they are pushed as the continents shift. The vertical pressure always generates the largest stress on a rock; the horizontal stresses on a rock will control the lateral spreading of the hydraulic fractures. Fractures tend to form in the direction of the least stress, which is generally horizontal. |
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| In some cases – the Marcellus Shale, for example – the distance between the gas/oil-bearing strata and the deepest fresh water aquifer is more than 5,000 feet. In others, as in the San Joaquin Valley, this distance can be more than 25,000 feet. | | In some cases – the Marcellus Shale, for example – the distance between the gas/oil-bearing strata and the deepest fresh water aquifer is more than 5,000 feet. In others, as in the San Joaquin Valley, this distance can be more than 25,000 feet. |
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− | The location and magnitude of created fractures typically are monitored using microseismic and tiltmeter technology, geophysical methods that measure very small seismic events and motion caused by breaks in the rock as it is fractured. The sensors used to measure these events, described as the equivalent to jumping one foot in the air and landing, allows operators to have a better understanding of the volume of rock that they are fracturing and where the cracks are forming. | + | The location and magnitude of created fractures typically are monitored using microseismic and tiltmeter technology, [[geophysical methods]] that measure very small seismic events and motion caused by breaks in the rock as it is fractured. The sensors used to measure these events, described as the equivalent to jumping one foot in the air and landing, allows operators to have a better understanding of the volume of rock that they are fracturing and where the cracks are forming. |
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| These monitoring programs show that the hydraulically formed fractures are located far from aquifers. | | These monitoring programs show that the hydraulically formed fractures are located far from aquifers. |
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| Global demand for oil and natural gas continues to grow, and will for decades to come. Meeting the needs of the developed and developing world alike will require the petroleum industry to find and produce new oil and natural gas resources. Hydraulic fracturing will help make this possible. | | Global demand for oil and natural gas continues to grow, and will for decades to come. Meeting the needs of the developed and developing world alike will require the petroleum industry to find and produce new oil and natural gas resources. Hydraulic fracturing will help make this possible. |
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| + | ==Annotated bibliography== |
| + | ===Basic Information about the Shale Resource and the Hydraulic Fracturing Processes:=== |
| + | * [http://emd.aapg.org/technical_areas/shalegas_liquids/index.cfm AAPG Energy Minerals Division information on shale resources] |
| + | * [http://energy.gov/fe/shale-gas-101 U.S. Department of Energy, Shale Gas 101] describes what it is, why it is important, and explains environmental challenges associated with its production. |
| + | * [https://fracfocus.org/hydraulic-fracturing-process Hydraulic Fracturing: How it Works], including the process, the site setup and fracturing fluid management, by FracFocus Chemical Registry. |
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| + | ===Economic Impact of shale development:=== |
| + | * [https://energy.duke.edu/shalepublicfinance Duke University (May 2016) finds that even a year after oil prices collapsed oil and gas development had positive impacts on most local governments that struggled to maintain roads and services during the boom]. |
| + | * [http://www.nber.org/papers/w21624 National Bureau of Economic Research study (October 2105) by Dartmouth professors] focuses on the income and employment consequences of fracking, finding that over a third of fracking revenue stays within the regional economy. |
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| + | ===Best Practices and Standards:=== |
| + | *[http://www.shalegas.energy.gov/resources/index.html U.S. Secretary of Energy Advisory Board Natural Gas Subcommittee report (2011)] gives best practice recommendations and documents their implementation in the final report. |
| + | ===State and Federal Regulation=== |
| + | * [http://www.epa.gov/airquality/oilandgas/pdfs/20120417changes.pdf EPA requires “Green Completions” by 2015] |
| + | * [https://www.federalregister.gov/articles/2013/06/10/2013-13708/oil-and-gas-hydraulic-fracturing-on-federal-and-indian-lands Bureau of Land Management (BLM) has proposed hydraulic fracturing rules for federal lands]. Federal courts have blocked enforcement of the rule. |
| + | * BLM released a [https://www.federalregister.gov/articles/2016/02/08/2016-01865/waste-prevention-production-subject-to-royalties-and-resource-conservation proposed rule to reduce venting and flaring] of natural gas in February 2016. The final rule is expected in late 2016. |
| + | * [https://www3.epa.gov/airquality/oilandgas/methane.html EPA plans to require data on equipment types and methane emissions from all well and facility operators]. The information would be used to apply the May 2016 rule for new sources to existing wells. |
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| + | ===Hydraulic Fracturing Fluids:=== |
| + | * [http://fracfocus.org/ FracFocus], sponsored by the Interstate Oil and Gas Compact Commission and the Ground Water Protection Council, lists chemicals used in over 100,000 wells. |
| + | * Baker Hughes, world’s third largest hydraulic fracturing service provider, has since 2014 provides a complete, public list of chemicals in its hydraulic fracturing fluids. |
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| + | ===Induced Seismicity:=== |
| + | * U.S. Geological Survey: “[http://earthquake.usgs.gov/research/induced/myths.php What you do and don’t know about induced seismicity]" & [http://www.usgs.gov/faq/taxonomy/term/9833 U.S. Geological Survey frequently asked questions about earthquakes caused by wastewater injection]. |
| + | * New U.S. Geological Survey “New Hazard Model for Induced Earthquakes” maps risk of damage from earthquakes (April 2016). |
| + | * [http://www.nap.edu/catalog.php?record_id=13355 U.S. National Research Council study on induced seismicity] (2013) (the PDF is free to download) |
| + | * The StatesFirst Induced Seismicity Work Group released its report (October 2015), “[http://www.statesfirstinitiative.org/#!induced-seismicity-work-group/cwed Potential Injection-Induced Seismicity Associated with Oil & Gas Development: A Primer on Technical and Regulatory Considerations Informing Risk Management and Mitigation].” StatesFirst is an initiative of the Interstate Oil and Gas Compact Commission (IOGCC) and the Ground Water Protection Council (GWPC). |
| + | * “[http://advances.sciencemag.org/content/1/5/e1500195 Oklahoma’s recent earthquakes and saltwater disposal]”: F. Rall Walsh III* and Mark D. Zoback (2015, Science Advances). Saltwater disposal is predominantly produced water, not hydraulic fracturing flow-back. |
| + | * Kansas Geological Survey monitoring and mitigation of earthquakes related to saltwater disposal, [http://www.kgs.ku.edu/PRS/Seismicity/2016/01-20-16_Legislative_Testimony_Seismicity.pdf report to the state legislature, January 2016]. |
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| + | ===Water Use for Hydraulic Fracturing=== |
| + | * [http://pubs.acs.org/doi/abs/10.1021/es502506v Comparison of Water Use for Hydraulic Fracturing for Unconventional Oil and Gas versus Conventional Oil], B.R. Scanlon and others, 2014, Environ. Sci. Technol. |
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| + | ===Methane in Aquifers:=== |
| + | * EPA draft assessment of the potential impacts of oil and gas hydraulic fracturing activities on the quality and quantity of drinking water resources in the United States released in June 2015. [http://www2.epa.gov/hfstudy/executive-summary-hydraulic-fracturing-study-draft-assessment-2015 Read executive summary or full report]. |
| + | ** Science Advisory Board Hydraulic Fracturing Research Advisory Panel documentation of its public meetings and peer review is [https://yosemite.epa.gov/sab/sabproduct.nsf/fedrgstr_activites/HF%20Drinking%20Water%20Assessment!OpenDocument&TableRow=2.2#2. here]. |
| + | * Methane and other gases occur in shallow aquifers and formations above the Marcellus, and predate Marcellus drilling: ”[http://archives.datapages.com/data/bulletns/2014/02feb/BLTN12178/BLTN12178.HTM A geochemical context for stray gas investigations in the northern Appalachian Basin: Implications of analyses of natural gases from Neogene-through Devonian-age strata]”, Fred J. Baldassare, AAPG Bull. V. 98, No. 2 (February 2014), P. 341–372. |
| + | * Methane found in water wells in the Denver-Julesburg basin, Colorado, is mostly microbially generated in shallow coal seams. About 0.06 to 0.15 percent of wells leaked thermogenic methane due to inadequate surface casing, casing leaks or wellhead-seal leaks ([http://www.pnas.org/content/early/2016/07/05/1523267113.full.pdf Owen Sherwood and others, 2016]). |
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| + | ===Methane Air Emissions: there is significant variation in measured, estimated or modeled values:=== |
| + | * National Energy Technology Lab: [http://www.netl.doe.gov/research/energy-analysis/life-cycle-analysis/lca-listing?prog=presentation Life Cycle Greenhouse Gas Emissions]: Natural Gas and Power Production presentation to EIA June 2015 Energy Conference. |
| + | * [http://www3.epa.gov/climatechange/ghgemissions/usinventoryreport.html EPA National Inventory] shows that 2013 methane emissions from natural as systems declined 12 percent from 2005, while production increased about 28 percent over the same period. |
| + | * [http://pubs.acs.org/journal/esthag Barnett Coordinated Measurement Campaign], seven articles in the July 7, 2015, Environ. Sci. Technol. v. 49, issue 13, document airborne measurements over the Barnett shale production region in Texas and the small number of “super emitters”. |
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| + | ===Traffic, Trucking Best Practices:=== |
| + | * [http://issuu.com/consumerenergyalliance/docs/trucking_safety_task_force/1 The American Petroleum Institute], the American Trucking Associations and the National Tank Truck Carriers have collected nearly two dozen recommendations for roadway safety and more considerate driving practices. |