Post on 03-Feb-2022
Unconventional Gas Development from Shale Plays: Myths and Realities Related to Human Health Impacts
A. R. Ingraffea, Ph.D., P.E. Cornell University and Physicians, Scientists, and Engineers for Sustainable and Healthy Energy, Inc. Halifax, Nova Scotia December 2, 2011
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Unconventional Development of Gas from Shale Formations:
Myths and Realities Related to Human Health Impacts
• Fracing is a 60-year-old Well-Proven Technology.
• Fluid Migration from Faulty Wells is a rare phenomenon.
• The use of multi-well pads and cluster drilling reduces surface impacts.
• Natural Gas is a Clean Fossil Fuel.
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• Fracing for gas development is a 60-year-old well-proven technology.
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Unconventional Development of Gas from Shale Formations:
Myths and Realities Related to Human Health Impacts
Why Is Shale Gas Development “Unconventional”
• Because it requires 4 technologies only recently combined to make
gas production from shales technically and economically feasible.
• Directional drilling: needed to access a thin layer of shale with long
laterals.
• High frac fluid volumes: needed to stimulate gas release from many
existing fractures.
• Slickwater: needed to control the amount of power needed to pump
large volumes of frac fluids, at high pressures, quickly, over long
distances, through small diameter casing.
• Clustered, Multi-well Pads: needed to access as much of the gas
inventory as possible, under constraints of leasing and capital.
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High Volume, Slickwater Fracing from Long Laterals (HVSFLL): The Concept
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~ 2000 m
~ 100 m Pay zone
Cap rock
Cap rock
Not to scale
The Lateral
Shale Layer
Why Is Shale Gas Development “Unconventional”
• Because it requires 4 technologies only recently combined to make
gas production from shales technically and economically feasible.
• Directional drilling: needed to access a thin layer of shale with long
laterals.
• High frac fluid volumes: needed to stimulate gas release from many
existing fractures.
• Slickwater: needed to control the amount of power needed to pump
large volumes of frac fluids, at high pressures, quickly, over long
distances, through small diameter casing.
• Clustered, Multi-well Pads: needed to access as much of the gas
inventory as possible, under constraints of leasing and capital.
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Early Joints at Taughannock Falls
Geneseo-Burket (Devonian black shale)
Taughannock Falls State Park, Trumansburg, N.Y.
Photo Courtesy T. Engelder
Gas Producing Shales are Heavily Fractured Naturally
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Why Is Shale Gas Development “Unconventional”
• Because it requires 4 technologies only recently combined to make
gas production from shales technically and economically feasible.
• Directional drilling: needed to access a thin layer of shale with long
laterals.
• High frac fluid volumes: needed to stimulate gas release from many
existing fractures.
• Slickwater: needed to control the amount of power needed to pump
large volumes of frac fluids, at high pressures, quickly, over long
distances, through small diameter casing.
• Clustered, Multi-well Pads: needed to access as much of the gas
inventory as possible, under constraints of leasing and capital.
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Targeting the Shale Layer Via Multiple, “Horizontal” Wells from Clusters of Pads
9 From Cody Teff, Shell Appalachia, WELL CONSTRUCTION PRACTICES IN THE MARCELLUS
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Example of Spatially Intense Development:
Dallas/Fort Worth Airport Property,
Barnett Shale Play
• 53 pads on 18,076 acres, 30 square miles
• Each red line is a well • Each red dot is a pad
• Almost complete coverage
• Patchwork, mostly ideal units • One developer
Summary of the Technology: HVSFLL Is a Recently Developed Process
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From NYS SGEIS revised draft, page 5-5, 2011
• Fracing for gas development is a 60-year-old well-proven technology.
Myth
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Truth • Unconventional development of gas using high
volume, slickwater fracing from long laterals is NOT a 60-year-old well-proven technology; it is still being
developed.
Health Impact • Insufficient time to conduct scientific investigations of
impacts due to process itself and inevitable accidents.
• Fluid Migration from Faulty Wells is a rare phenomenon.
Unconventional Development of Gas from Shale Formations:
Myths and Realities Related to Human Health Impacts
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Gas Is Supposed to Rise Inside the Production Casing,
Not Outside
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VIDEO of
Methane Bubbling
At Well Head
Bubbling in Muncy Creek, Lycoming County, PA: Example of Migration of Hydrocarbons
Video Courtesy of Ralph Kisberg, Responsible Drilling Alliance 15
Observation: What Does This All Look Like “Downhole”?
Laboratory-Scale Experiment: • A Block of Real Rock
• Drill It, Right Down the Middle
• Case It
• Cement It
• Perforate It
• Frac It, with Red Dye in the Frac Fluid
• Break Open the Block
• See What Happened
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One Can See Perforations and Hydraulic Fractures
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4 in.
FRESH WATER AQUIFER ZONE
SHALLOW PRODUCING ZONE
INTERMEDIATE PRODUCING ZONE
CONDUCTOR PIPE
SURFACE CASING
PRODUCTION CASING
GOOD MECHANICAL INTEGRITY
TARGET PRODUCING ZONE 18
CEMENT CHANNELING
PRESSURE BUILDS UP
CONDUCTOR PIPE
SURFACE CASING
PRODUCTION CASING
FRESH WATER AQUIFER ZONE
SHALLOW PRODUCING ZONE
INTERMEDIATE PRODUCING ZONE
TARGET PRODUCING ZONE
CA
SIN
G
CEM
ENT
FOR
MA
TIO
N
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LEAK THROUGH CASING
CONDUCTOR PIPE
SURFACE CASING
PRODUCTION CASING
FOR
MA
TIO
N
CA
SIN
G
FRESH WATER AQUIFER ZONE
SHALLOW PRODUCING ZONE
INTERMEDIATE PRODUCING ZONE
TARGET PRODUCING ZONE
PRESSURE BUILDS UP
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INSUFFICIENT CEMENT COVERAGE
PRESSURE BUILDS UP
CONDUCTOR PIPE
SURFACE CASING
PRODUCTION CASING
FRESH WATER AQUIFER ZONE
SHALLOW PRODUCING ZONE
INTERMEDIATE PRODUCING ZONE
TARGET PRODUCING ZONE 21
22 From Watson, PAPER 2004-297Petroleum Society’s 5th Canadian International Petroleum Conference
Mechanisms of Gas Migration • Gas Migration Through Cement: percolation during
curing
• Cement Sheath Failure: high temp, high pressure, perforation
• Improper Cement Design and Placement: poor chemistry, poor mud cleanup, low cement top
• Casing Failure: Corrosion, joint failure, fracture
• Cross Flow Between Adjacent Wells
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From Watson, PAPER 2004-297Petroleum Society’s 5th Canadian International Petroleum Conference
“Since the earliest gas wells, uncontrolled migration of hydrocarbons to the surface has
challenged the oil and gas industry”
Brufatto et al., Oilfield Review, Schlumberger, Autumn, 2003
SCP=Sustained Casing Pressure. Also called sustained annular pressure in one or more of the casing annuli.
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Sustained Casing Pressure and Gas Migration Are Chronic Problems
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Watson and Bachu, SPE 106817, 2009.
New Scientific Data on Methane Contamination of Water Wells
26 www.pnas.org/cgi/doi/10.1073/pnas.1100682108
• Fluid Migration from Faulty Wells is a rare phenomenon
Myth
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Truth • Fluid Migration from Faulty Wells is a well-
known, chronic problem with an expected rate of occurrence.
Health Impact • Contamination of USDW with drilling fluid, frac fluid,
released hydrocarbons.
• The use of clustered, multi-well pads reduces surface impacts.
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Unconventional Development of Gas from Shale Formations:
Myths and Realities Related to Human Health Impacts
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Example: Dallas/Fort Worth Airport Property,
Barnett Shale Play
• 53 pads on 18,076 acres,30 square miles
• Each red dot is a pad • Each red line is a well
• Almost complete coverage
• Patchwork, mostly ideal units • One developer
The Barnett Shale Play, Texas
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Dimock, Pennsylvania
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32
?????
Horn River Area, NE British Columbia
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Encana Says “No!” This One Is It
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417 million gallons of water 78,400 tons of sand 8 milllion gallons of fracing chemicals 500 frac intervals 10,000 foot laterals 40,000 hp for fracing pumps
Notice NNW-SSE orientation of
non-square, about 256ha,
spacing unit. Geology and
leasing control.
Direction of max
horizontal stress
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An Industrial-Ideal Pad/Well Buildout Scenario:NS
Clustering of Pads in Tioga County, PA
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• The use of multi-well pads and cluster drilling reduces surface impacts.
Myth
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• The use of multi-well pads and cluster drilling facilitates and prolongs intense industrialization and leaves a larger, long-term footprint.
Truth
Health Impact • Long term noise, dust, light pollution; NOx
emissions; higher spill probabilities of frac fluid; venting and accidental emissions of produced gases.
• Natural Gas is a Clean Fossil Fuel.
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Unconventional Development of Gas from Shale Formations:
Myths and Realities Related to Human Health Impacts
CO2 Concentration in the Atmosphere
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Seasonal fluctuation
2 ppm increase per year 450 ppm a “tipping point” We have about 30 years…
Methane Concentration in the Atmosphere: Historical Record
42 http://www.ecen.com/eee55/eee55e/growth_of%20methane_concentration_in_atmosphere.htm
Methane Is a Much More Potent Greenhouse Gas than Carbon Dioxide: 105 time more Potent over 20 years, 33 Times over 100 years. It Is Vented and Leaked….
• During initial frac fluid flow-back period
• Routinely and continuously at the well site
• During liquid unloading
• During gas processing
• During transmission, storage, and distribution
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Marcellus Well Being “Finished” Outside Dimock, Pa June, 2011: Major Source of Methane Emission
Photo and FLIR Methane-Tuned Video Courtesy Frank Finan 44
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Marcellus Well Being “Finished” Outside Dimock, Pa. June, 2011: Major Source of Methane Emission
Video
Video courtesy of Frank Finan
Burn-Offs at MarkWest Gas Processing Plant, Houston, PA
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9/18/11
2:03pm
Photos courtesy of Robert Donnan
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Burn-Offs at MarkWest Gas Processing Plant, Houston, PA
9/28/11
7:28pm
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The Literature on Methane Emissions from Shale Gas Development (* = Peer Reviewed)
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1. Howarth R W, Santoro R & Ingraffea A. Clim. Change 106, 679–690 (2011).*
2. Skone T.
http://cce.cornell.edu/EnergyClimateChange/NaturalGasDev/Documents/PDFs/SKONE_
NG_LC_GHG_Profile_Cornell_12MAY11_Final.pdf
3. Hughes D. Post Carbon Institute, 2011; http://go.nature.com/gkboqm
4. Osborn S G., Vengosh A, Warner NR & Jackson RB. Proc. Natl Acad. Sci. USA, 108,
8172–8176 (2011). *
5. Kumar S. WorldWatch Institute, http://www.worldwatch.org/despite-methane-
emissions-upstream-natural-gas-cleaner-coal-life-cycle-basi.s
5. Jiang M, Griffin W M, Hendrickson C, Jaramillo P, VanBriesen J & Venkatesh A.
Environ. Res. Lett. 6: 034014 (2011).*
6. Wigley T.. Clim. Change (2011). DOI 10.1007/s10584-011-0217-3.*
Time scale GWP heat/ Methane Methane (years) electricity from gas from coal (gC/MJ) (gC/MJ) Howarth et al. 20 / 100 33 / 105 both 0.56 – 1.3 0.045 – 0.14 Hughes 20 / 100 33 / 105 both 0.56 – 1.3 0.045 – 0.14 Skone 100 25 electr. 0.34 0.17 Jiang et al. 100 25 electr. 0.40 Not reported Worldwatch 100 25 electr. 0.34 0.094 Wigley 0 – 200 n/a electr. 0.34 – 1.4 0.107 U.S. EPA (2011) n/a n/a n/a 0.75 0.04
Comparison of Modeling Assumptions and Key Results
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• Natural Gas is a Clean Fossil Fuel. Myth
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• Over its life-cycle, unconventional Natural Gas is likely no cleaner than coal or petroleum, and conventional gas is comparable to those other fossil fuels.
Truth
Health Impact • Exacerbation of global climate change.
Why Is Slickwater, High-Volume Fracing from Long Laterals a Higher Risk to Public Health?
• Requires much higher well density, many wells per square mile.
• Requires much more industrial development over large areas, heavy equipment operating 24/7/365.
• Requires much higher volumes of fracing fluid, millions of gallons per well.
• Produces much higher volumes of waste fluids and solids containing hazardous materials: frac fluid chemicals, heavy metals, NORMS, NOx, VOC’s.
• Produces higher volumes of fugitive emissions of methane.
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• As number of wells and volumes of waste increase, probability of accidental releases of hazardous materials into air and groundwater increases.
• Cumulative effects on air and water and health from these and from purposeful emissions into the atmosphere and releases into groundwater are unknown.
• Increased production, processing, storage, transportation and burning of natural gas and its liquid companions (e.g. ethane, propane, butane) increases emission of GHG’s.
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Why Is Slickwater, High-Volume Fracing from Long Laterals a Higher Risk to Public Health?
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http://www.psehealthyenergy.org/
Where Can You
Find Reliable
Information?
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Where Can You
Find Reliable
Information?
http://www.earthworksaction.org/oil_and_gas.cfm
Thank You for Attending and Participating Tonight
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The Barnett Shale Play, Texas
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Dimock, Pennsylvania
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An Industrial-Ideal Pad/Well Buildout Scenario:Fredericton
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An Industrial-Ideal Pad/Well Buildout Scenario:NS
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An Industrial-Ideal Pad/Well Buildout Scenario: Mocton
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An Industrial-Ideal Pad/Well Buildout Scenario:Fredericton