Unconventional Natural Gas

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Unconventional Natural Gas

• Kenneth M. Klemow, Ph.D.
• BIO / EES 105 at Wilkes University

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What is unconventional natural gas?

• Natural gas extracted from sources difficult to
  obtain through conventional drilling techniques.
• Deep sources (gt15,000)
• Unconventional natural gas derived from dense
  (tight) rock formations
• Shale
• Tight sandstone
• Coal bed methane
• Geopressurized zones
• Methane hydrates

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Geologists have long known of gas in tight rock

• Technology didnt exist to extract that gas in
  marketable quantities.

http//www.wintershall.com/en/different-types-of-r
eserves-tight-gas-and-shale-gas.html
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Extracting gas from tight formations

• Problems
• Occurs in rock that has low permeability
• Gas locked in small fractures / bubbles
• Much gas associated with horizontally bedded rock

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Extracting gas from tight rock possible due to
two technologies
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Horizontal drilling

• Well drilled vertically to gas rich zone, then
  turned horizontally
• Possible due to advanced drill bits

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History of horizontal drilling

• First used in WWII in oil wells of northern PA
• During 1970s, expanded to much of the Appalachian
  basin
• Later employed in large scale in Barnett shales
  of Texas.

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Hydraulic fracturing (HF, fracking)

• Fluid forced down wellbore under high pressure
• Open crevices in rocks to liberate methane

http//savethewater.org/
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Fracking fluid composed of various components
Component Purpose
Water Primary solvent
Sand Prop open pores
Biocides Kill bacteria
Scale inhibitors Prevent scale on wellbore
Lubricant Promote flow through pumps pipes
Corrosion inhibitors Prevent rust from forming
Gelling agents Thicken solution to promote proppant movement
Acid Dissolve debris in wellbore, opening it up
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HF not a new technology

• HF first used in 1947 in an oil well in Grant
  County, Kansas.
• By 2002, used approximately a million times in
  US.
• Up to 95 of wells drilled today are
  hydraulically fractured, accounting for more than
  67 of natural gas production.

https//student.societyforscience.org/article/frac
king-fuels-energy-debate
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Development of Marcellus

• First attempted by Range Resources in Washington
  County PA in 2004
• By 2006 other companies started buying and
  leasing land

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Benefits of horizontal drilling

• Need fewer wells and well pads to obtain gas from
  rock
• Thus less surface damage

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Worldwide distribution of UNG
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US Distribution of UNG
http//need-media.smugmug.com
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How much gas is there?

• Different estimates
• Total in place
• Technically recoverable
• Proven
• Unproven
• Estimates difficult
• Undiscovered shale
• Several variables
• gas content in given volume of shale
• recoverable of total
• Depletion rates of wells

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Technically recoverable gas (Tcf)(EIA 2013)

• World 7,299
• China 1,115
• Argentina 802
• Algeria 707
• US 665
• Canada 573
• Annual consumption
• Worldwide 113 Tcf
• US 24
• 1 Tcf can heat 15 million homes for a year
• Much uncertainty
• Behr (2013) http//www.eenews.net/stories/10599761
  02

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(No Transcript)
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One view of shale gas supplies
http//www.globalresearch.ca/
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Issues associated with unconventional gas
development

• Water consumption
• Wastewater disposal
• Potential groundwater pollution
• Habitat fragmentation
• Potential surface water pollution
• Air pollution
• Health issues

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Water consumption

• Each well requires 4-6 million gallons of water
• Generally taken from regional waterbodies
• In eastern PA, regulated by SRBC
• Give permits for all withdrawals
• Deny during drought conditions
• No similar agency for western PA
• Proposal to use abandoned mine drainage

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Water use in relation to other activities
http//fracfocus.org/water-protection/hydraulic-fr
acturing-usage
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Wastewater disposal

• Approx. 20-80 of water injected returns as
  flowback and produced water
• High levels of salinity, radioactivity
• Stored in onsite holding tanks
• Once treated in municipal treatment facilities
• Now specialized treatment
• Clean water returned to drillers
• Brine trucked to disposal site

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Groundwater pollution

• Drilling fluid contains toxic substances
• Flowback and produced water contains salts,
  radioactivity and methane.
• Studies indicate methane leakage

Osborne et al (2011)
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Habitat fragmentation
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Potential surface water pollution

• Spills from flowback
• Holding pond accidents
• Release of wastewater
• Waste water shipping accidents
• Poor ES control measures

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Air pollution

• Fugitive methane
• Ozone
• Particulate matter
• Diesel exhaust
• Carbon monoxide
• Nitrous oxide
• Sulfur dioxide
• BTEX

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Health issues

• Some HF chemicals carcinogenic
• Suggested links to autism, respiratory,
  cardiovascular, neurologic problems, loss of
  taste and smell
• Mostly anecdotal
• Studies being conducted mostly epidemiological

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Quality of life

• Industrialization of rural landscape
• Displacement of families

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Earthquakes

• Injection of wastewater into boreholes may
  trigger earthquakes
• Some concern that HD and HF may cumulatively
  cause seismic activity

http//www.huffingtonpost.com/2011/04/21/
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Longevity of wells a question
http//www.leebsmarketforecast.com
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Shale gas moratoria - US

• In place
• New York State
• New Jersey
• Delaware basin
• Mora County, NM
• Proposed
• Pennsylvania
• Colorado

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European moratoria
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Coalbed methane

• Associated with coal seams
• Once a nuisance and vented
• Now efforts to collect
• May represent 8 of NG supplies

http//www.naturalgas.org/overview/unconvent_ng_re
source.asp
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Geopressurized methane

• Methane in porous rock overtopped by clay layer
• At depth of 10,000-25,000
• Thus under tremendous pressure
• May hold 5,000 49,000 TCF of methane
• Compare with 1,100 TCF of known reserves
• Not possible to extract with current technology

http//www.naturalgas.org/overview/unconvent_ng_re
source.asp
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Methane hydrates

• Molecules of methane surrounded by cage of
  frozen water
• Found in seafloor and Arctic soils
• May contain 7000 73,000 Tcf of methane
• More than all coal, oil and natural gas combined
• Research in its infancy
• Utilization may impact global carbon cycle

http//www.naturalgas.org/overview/unconvent_ng_re
source.asp
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Global distribution of methane hydrates
http//www.wou.edu/las/physci/Energy/Gas_Hydrates.
html
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Conclusions

• Unconventional gas has changed the energy picture
  in the US and worldwide
• Due to improvements in extraction technology
• Supporters believe that UNG can supply energy
  needs for decades, if not longer
• In US, can relieve need to import energy
• Detractors point to many risks
• Science critically needed
• What to do in the mean