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Unconventional Natural Gas

Learn about unconventional natural gas sources, extraction methods, technologies like horizontal drilling and hydraulic fracturing, and the global impact. Discover the benefits and issues associated with this resource, including water consumption, wastewater disposal, pollution concerns, and health risks.

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Unconventional Natural Gas

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  1. Unconventional Natural Gas Kenneth M. Klemow, Ph.D. BIO / EES 105 at Wilkes University

  2. What is unconventional natural gas? • Natural gas extracted from sources difficult to obtain through conventional drilling techniques. • Deep sources (>15,000’) • Unconventional natural gas derived from dense (tight) rock formations: • Shale • Tight sandstone • Coal bed methane • Geopressurized zones • Methane hydrates

  3. Geologists have long known of gas in tight rock • Technology didn’t exist to extract that gas in marketable quantities. http://www.wintershall.com/en/different-types-of-reserves-tight-gas-and-shale-gas.html

  4. 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

  5. Extracting gas from tight rock possible due to two technologies http://magazine.mst.edu http://energy.umich.edu/ Horizontal drilling Hydraulic fracturing

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

  7. 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.

  8. Hydraulic fracturing (HF, “fracking”) • Fluid forced down wellbore under high pressure • Open crevices in rocks to liberate methane http://savethewater.org/

  9. Fracking fluid composed of various components

  10. 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/fracking-fuels-energy-debate

  11. Development of Marcellus • First attempted by Range Resources in Washington County PA in 2004 • By 2006 other companies started buying and leasing land http://www.ogj.com/articles/uogr/print/

  12. Benefits of horizontal drilling • Need fewer wells and well pads to obtain gas from rock • Thus less surface damage Vertical Drilling (WY) Horizontal Drilling (PA)

  13. Worldwide distribution of UNG

  14. US Distribution of UNG http://need-media.smugmug.com

  15. 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

  16. 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/1059976102

  17. One view of shale gas supplies http://www.globalresearch.ca/

  18. Issues associated with unconventional gas development • Water consumption • Wastewater disposal • Potential groundwater pollution • Habitat fragmentation • Potential surface water pollution • Air pollution • Health issues

  19. 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 http://alleghenydefenseproject.files.wordpress.com http://ecowatch.com

  20. Water use in relation to other activities http://fracfocus.org/water-protection/hydraulic-fracturing-usage

  21. 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 http://www.ogpe.com/articles

  22. Groundwater pollution • Drilling fluid contains toxic substances • Flowback and produced water contains salts, radioactivity and methane. • Studies indicate methane leakage Osborne et al (2011)

  23. Habitat fragmentation

  24. Potential surface water pollution • Spills from flowback • Holding pond accidents • Release of wastewater • Waste water shipping accidents • Poor E&S control measures http://cen.acs.org/ http://www.gcbl.org

  25. Air pollution • Fugitive methane • Ozone • Particulate matter • Diesel exhaust • Carbon monoxide • Nitrous oxide • Sulfur dioxide • BTEX http://www.telegraph.co.uk/

  26. 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 http://news.nationalgeographic.com

  27. Quality of life • Industrialization of rural landscape • Displacement of families http://www.lowersusquehannariverkeeper.org/ http://money.cnn.com/

  28. 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/

  29. Longevity of wells a question http://www.leebsmarketforecast.com

  30. Shale gas moratoria - US • In place • New York State • New Jersey • Delaware basin • Mora County, NM • Proposed • Pennsylvania • Colorado

  31. European moratoria

  32. 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_resource.asp

  33. 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_resource.asp

  34. 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_resource.asp

  35. Global distribution of methane hydrates http://www.wou.edu/las/physci/Energy/Gas_Hydrates.html

  36. 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

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