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Copyright T. Bechtel Franklin & Marshall College 2014 Copyright T. Bechtel Franklin & Marshall College 2014 What’s Going on Down There ?!? Timothy D. Bechtel,

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Presentation on theme: "Copyright T. Bechtel Franklin & Marshall College 2014 Copyright T. Bechtel Franklin & Marshall College 2014 What’s Going on Down There ?!? Timothy D. Bechtel,"— Presentation transcript:

1 Copyright T. Bechtel Franklin & Marshall College 2014 Copyright T. Bechtel Franklin & Marshall College 2014 What’s Going on Down There ?!? Timothy D. Bechtel, Ph.D., P.G. Department of Earth & Environment Franklin & Marshall College Hydraulic Fracturing

2 Copyright T. Bechtel Franklin & Marshall College 2014 Life Cycle of an Unconventional O&G Well 1.Site Selection 2.Pad Construction 3.Drilling and Casing 4.Stimulation a.Perforation b.Hydraulic Fracturing c.Fracture Monitoring d.Fracture Controls 5.Flowback 6.Production 7.Closure “Fracking” “Fracing” Frac’ing

3 Copyright T. Bechtel Franklin & Marshall College Site Selection C. Scotese; The Paleomap Project

4 Copyright T. Bechtel Franklin & Marshall College 2014 The Modern “Shale Fairway” EMR Canada

5 Copyright T. Bechtel Franklin & Marshall College 2014 The Catskill Basin L. Fichter; JMU

6 Copyright T. Bechtel Franklin & Marshall College 2014 The Result of All This…

7 Copyright T. Bechtel Franklin & Marshall College 2014 Black Shale Phytoplankton, algae, pollen, spores eaten by zooplankton eaten by fish and other macro- organisms 0.05mm Die and rain down to make a slimy mud Far enough offshore for fine sediments only Reducing bottom conditions for preservation poor circulation/anoxia/euxinia Compressed to make kerogen Organic matter also collects NORM USGS At each trophic level, biomass is reduced by a factor of ten

8 Copyright T. Bechtel Franklin & Marshall College 2014 Marcellus Ingredients Illite Chlorite Quartz Kerogen: ~4 to 15% Feldspar Micas Calcite Pyrite Porosity: ~6 to 10% Permeability: ~0.005 to 2  d (Soeder, 1988)

9 Copyright T. Bechtel Franklin & Marshall College 2014 What Does microDarcy mean? King,  d0.005  d

10 Copyright T. Bechtel Franklin & Marshall College 2014 Biogenic vs. Thermogenic Gas EMR Canada At depth, kerogen is broken down to make hydrocarbons Biogenic gas is only methane – produced as microbes decompose kerogen Thermogenic gas is produced by cracking and can generate “wet gas” with methane plus easily liquified ethane, propane, and butane At the bottom of the gas window, elevated heat generates “dry gas” with methane only Hydrogen and Carbon isotope ratios can discriminate between biogenic and thermogenic gas

11 Copyright T. Bechtel Franklin & Marshall College 2014 Current Hot Spots Shallow Wet Gas Deep High Pressure Dry Gas 3676 Registered Wells (fracfocus.org, 02/17/2014)

12 Copyright T. Bechtel Franklin & Marshall College Pad Construction Roads for transport of heavy equipment for earth moving, materials transport, and the drill rig itself Site leveling Erosion and sediment control structures Pits for drilling fluids, cuttings, and flowback Racks for drill string and casing sections Intense activity on the site and local roads for several weeks Towanda, PA October, 2010 Steve Hargreaves/CNN shale.us/Marcellus-Air- 8.htm June, 2012

13 Copyright T. Bechtel Franklin & Marshall College Drilling and Casing Drill rig, drill string, drill bit Waynesburg, PA Steve Hargreaves/CNN ABC News Philly.com

14 Copyright T. Bechtel Franklin & Marshall College 2014 Drilling Mud Energy Institute Water plus bentonite clay and barite (maybe xantham or guar gum) –Lubricates –Cools –Lifts cuttings Chips separated on a shale shaker screen –Provides weight to prevent blow-outs –Provides power for mud drive bits –Re-circulated –Recycled –May pick-up NORM Joshua Doubek

15 Copyright T. Bechtel Franklin & Marshall College 2014 Casing Conductor Casing –Stabilizes unconsolidated surface material –24” diameter –Extends approximately 50 feet –Cemented from bottom to surface Surface Casing –Protects shallow fresh water aquifers –20” diameter –Extends ~500 feet –Cemented from bottom to surface Intermediate Casing –Protects deeper (often brackish) water –13 3 / 8 ”diameter –Extends ~1,000 feet –Cemented bottom to surface Production Casing –Conveys fluids to and from the formation –5 1 / 2 ” diameter –Extends to 5,000 to 10,000 feet in depth –Extends 3,000 to 12,000 feet horizontally –Cemented from toe to surface NYS Water Resources Institute Springer Nearly all (?) the horror stories result from human error here

16 Copyright T. Bechtel Franklin & Marshall College 2014

17 Copyright T. Bechtel Franklin & Marshall College Stimulation Perforation –At completion, the production casing is not in communication with the formation –Explosive charges in a perf gun are used to punch holes through the casing and cement Baker Hughes

18 Copyright T. Bechtel Franklin & Marshall College a. Hydraulic Fracturing Each well is frac’ed in stages –Perf gun shoots holes through the casing/grout –Stage is sealed with packer or ball in a seat –Fluid is pumped in at high flow rate and high pressure –Existing and incipient fractures are forced open T. Engelder Natural Hydraulic Fractures

19 Copyright T. Bechtel Franklin & Marshall College 2014 History Directional drilling (not new) –Patented in 1859 (for brine wells) –Used to relieve blowouts since ~1925 Hydraulic Fracturing (not new) –First hydrofrac job in the Hugoton Field, Kansas, 1947 Nitroglycerine frac’ing in 1890s to 1920s (yikes!) Project Gasbuggy nuclear frac’ing in 1967 (double yikes!!) –For the last 40 + years, 94% of gas wells have been “stimulated” New Combination of these two –US DOE Eastern Shale Gas Project ( ) Initiated in response to OPEC hostilities Deemed feasible, but not economic New economics –dwindling (conventional) supply –increasing demand Plus high volume, high pressure 1869; AlleganyHistory.org

20 Copyright T. Bechtel Franklin & Marshall College 2014 Hugoton Field, 1947 Stanolind Oil This is what the first frac job looked like

21 Copyright T. Bechtel Franklin & Marshall College 2014 Eagleford Field, 2012 Now it looks like this

22 Copyright T. Bechtel Franklin & Marshall College 2014 Schematic Water Hydrator Gel Concentrate Blender Chemical 1 Chemical 2 Chemical 3 Chemical n Sand Can Pump Well Flowback High Volume High Pressure

23 Copyright T. Bechtel Franklin & Marshall College 2014 Dusseault & McLennan, 2009 What is Happening Underground? Remember 2  d ~ concrete

24 Copyright T. Bechtel Franklin & Marshall College 2014 Fracture Mechanics In each frac stage; –Fractures open primarily perpendicular to  3 (horizontal) –Fractures propagate preferentially upward (towards the free surface) –Typically follow natural pre-existing or incipient hydraulic fractures –Proppants hold them open when the injection pressure is released –The “dilated zone” is much larger than the “sand zone” Shearing and self-propping on minutely flexed discontinuities beyond the sand zone and even beyond the dilated zone enhance permeability Stress Ellipse (at a point) 33 11 Crack opening/orientation –Walls push against  3 –Propagates along  1

25 Copyright T. Bechtel Franklin & Marshall College 2014 The Nature of the Stimulated Zone Kaiser et al., 2013 Cracks propagate along  1 or  max –Makes sense; they open by pushing against  3 or  min Proppant does not go far –Stays in “sand zone” –Creates a halo “dilated zone” Cracks in dilated zone and beyond are “self-propping”

26 Copyright T. Bechtel Franklin & Marshall College 2014 Demo Time Plates and shims for fracture wedging (Mode I) Phone book demo for shearing (Modes II and III) outside the dilated zone (and rough surfaces are self-propping – like wrinkled paper) Stack of blocks for widespread wedging and shearing (with self propping) in a naturally fractured rock mass

27 Copyright T. Bechtel Franklin & Marshall College 2014 How do we know what is going on a mile or more down and several miles away? Frac job monitoring (Nolte-Smith Plots) –Injection rate and bottomhole pressure (BHP) Tilt Meter monitoring –“dilated” zones Mine-Back experiments –Expensive and rare Microseismic monitoring –Acoustic emissions Events with magnitudes 1000 to times smaller than any perceptible earthquake –Drop a jug of milk

28 Copyright T. Bechtel Franklin & Marshall College 2014 Microseismic Monitoring EMR Canada Colors show frac stages

29 Copyright T. Bechtel Franklin & Marshall College 2014 How High Can they Propagate? 1.High strength units form intended frac barriers o But are there pre-existing tectonic features?

30 Copyright T. Bechtel Franklin & Marshall College 2014 How High Can they Propagate? 2.The state of stress will not allow vertical fractures at shallow depths o But are there pre-existing tectonic features? Vertical fractures Horizontal fractures

31 Copyright T. Bechtel Franklin & Marshall College 2014 How High Can They Propagate? 3.If a fracture does “go rogue”, it will stop the moment it encounters a permeable layer –Pressure “bleed-off” Environmentally undesirable since this could be a migration pathway for fluids Economically undesirable since this could lead to loss of product –BHP is closely monitored to prevent this Human error ?

32 Copyright T. Bechtel Franklin & Marshall College 2014 How High Can they Propagate? 4.Zones that are frac’ed are typically much deeper than potable wells o But are there pre-existing tectonic features? o And are there abandoned O&G wells that extend deeper? Marcellus Shale (Pinnacle, 2010)

33 Copyright T. Bechtel Franklin & Marshall College Flowback, 6. Production Flowback –Gas pressure pushes frac water back out –Flowback can go on from hours to weeks –Later water is chemically connate* Not frac fluid Flaring –CH 4 as GHG is 24x more powerful than C0 2 Production –Fluid gradients are towards the well By pipeline? Truck? –Connections = fugitive gas –CH 4 24x more powerful than C0 2 * Brine with NORM, bromides, arsenic, lead, hydrocarbons

34 Copyright T. Bechtel Franklin & Marshall College Closure Typically requires cement/bentonite plugs, e.g.; –200-foot plug straddling the end of the surface casing shoe –Plug across any oil and gas bearing strata that extends 100 feet above –Plug extending from 50 feet below to 50 feet above any water- bearing strata –50-foot plug at the surface of the wellbore Groundwater Protection Council, 2011

35 Copyright T. Bechtel Franklin & Marshall College 2014 Common Concerns Distribution (5 years worth of energy, but UGI says 100 years to build pipelines) Consumptive use of fresh water (>30% of US frack jobs occur in chronic drought areas) Waste fluids (cuttings, drilling mud, and flowback) Pad clearing (~10 acres per pad, but also roads and pipelines – destruction, degradation and fragmentation) Road building (high volume of heavy trucks on rural roads) Drinking water CH 4 (biogenic? CBM? Natural pre-existing?) Rogue fractures (Davies et al., 2012: 1% of fractures extend >500m) Fault reactivation (detected by microseismic monitoring) Induced earthquakes (related to deep injection disposal not frac’ing) Fugitive emissions (Low CO 2 from NG vs. GHG power of CH 4 -- Cornell vs. NRDC et al.) VOC emissions (frac water additives and flowback hydrocarbons) Radiation (Radium in fluids, in wells, in cuttings, and Radon in the atmosphere and product, etc.) Migration of lost frac water (this is the one with no evidence; too recent, or prevented by pressure gradient?) Rise in STD’s documented in drilling areas (relative to…?) Dust control (mostly in the arid west) Light pollution and landscape pollution (e.g. State and National Parks and Forests) Induced landslides Blooms of golden algae (salinization of surface waters) Workers’ exposure to chemicals and proppants Community disruption Thousands of abandoned wells (from previous O&G era – next slide) Is it really an energy resource? (EROI slide also coming up…) All of these must be addressed if we use “fracking” to mean the entire process

36 Copyright T. Bechtel Franklin & Marshall College 2014 Preachy Stuff Warning

37 Copyright T. Bechtel Franklin & Marshall College 2014 The “News” is Often Uninformed or Spun

38 Copyright T. Bechtel Franklin & Marshall College 2014 I Encourage You to Ponder… How is it different from conventional oil and gas? Do we need it ? Should we do it ? Should we ban it ? Should we regulate it ? –How tightly ? –What level of taxation ? Could it be a “bridge” to renewables (replacing coal)? Will we use it as a bridge ? –Or as energy-hungry humans burn it PLUS coal ? Are any of the concerns truly intractable from an engineering standpoint? –What level of risk do we accept for other energy sources ? –What about human error ? Useful conversations must avoid conflation of distinct issues

39 Copyright T. Bechtel Franklin & Marshall College 2014 And, Anecdotes are not Evidence Osborne et al. (2011 and 2013)

40 Copyright T. Bechtel Franklin & Marshall College 2014 Any Questions ?

41 Copyright T. Bechtel Franklin & Marshall College 2014 PA DEP estimates that out of >320,000 wells drilled since 1859, less than 4% have been found and plugged (2871 total since 1989, 23 last year)

42 Copyright T. Bechtel Franklin & Marshall College 2014 Energy Payback Ratio “cradle to grave” Break Even Charles Hall (Energy and the Wealth of Nations): “First World societies require an EROI greater than 15 for all energy production to provide enough net energy to sustain food production, water supply, housing, culture, transport, communications, advance science, health care, defense, etc.” Shale Gas Estimates Hughes, 2013 Aucott, st World Lifestyle


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