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

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Presentation on theme: "Unconventional Natural Gas Kenneth M. Klemow, Ph.D. BIO / EES 105 at Wilkes University."— Presentation transcript:

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.

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 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

9 Fracking fluid composed of various components ComponentPurpose WaterPrimary solvent SandProp open pores BiocidesKill bacteria Scale inhibitorsPrevent scale on wellbore LubricantPromote flow through pumps & pipes Corrosion inhibitorsPrevent rust from forming Gelling agentsThicken solution to promote proppant movement AcidDissolve debris in wellbore, opening it up

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/frackin g-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

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

13 Worldwide distribution of UNG

14 US Distribution of UNG

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)

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18 One view of shale gas supplies

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

20 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

21 Water use in relation to other activities

22 Wastewater disposal Approx % 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

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

24 Habitat fragmentation

25 Potential surface water pollution Spills from flowback Holding pond accidents Release of wastewater Waste water shipping accidents Poor E&S control measures

26 Air pollution Fugitive methane Ozone Particulate matter Diesel exhaust ◦ Carbon monoxide ◦ Nitrous oxide ◦ Sulfur dioxide BTEX

27 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

28 Quality of life Industrialization of rural landscape Displacement of families

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

30 Longevity of wells a question

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

32 European moratoria

33 Coalbed methane Associated with coal seams Once a nuisance and vented Now efforts to collect May represent 8% of NG supplies

34 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

35 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

36 Global distribution of methane hydrates

37 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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