7/21/2014
Just How Much is Out There?
(and Why?)
Themes
• Quality, not quantity
• Technology changes reality
• There’s no free lunch
Alan Carroll
Department of Geoscience
University of Wisconsin-Madison
Quality, Not Quantity
The Resource
Pyramid
It’s hot!
Spindletop
Gusher
1901
• Total energy available on Earth is many
thousands of times greater than needed
• What matters however is energy that
can be used efficiently and cheaply
• Resource quality and quantity are
inversely related
• Naturally concentrated = higher quality
• We will run out of money long
before we run out of energy!
Technology Changes
Reality…
Oil Shale
Solar Photovoltaic
Module Cost
7
6
5
4
$/watt
Hand-Dug Well
Cable Tools
Rotary Drilling
Offshore Drilling
3
“Fracking”
2
Cost decreased by 2/3 between 1990 and 2010
1
Data: DOE EIA
0
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
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7/21/2014
There’s No Free Lunch…
NREL
Energy
Geography
• Greatest solar potential in
southwest
• Greatest electricity demand
in northeast
IPCC 2013
• Similar problem with wind
Photosynthesis:
Geofuels:
Solar energy
stored in the
Earth’s crust
The Geologic Solar Collector
6CO2+6H2O+light→
• Total organic carbon
buried in Earth’s crust
contains the energy
equivalent of about 100
years of sunlight, captured
over ~500 million years
C6H12O6+6O2
NOAA
Plants
Phytoplankton
(terrestrial)
SERC
Jon Sullivan
(marine,
lacustrine)
• Presently recognized fossil
fuels contain the energy
equivalent of only about 1
week of sunlight
BLM
Wyoming coal
Baku gas seep
History of Carbon
Baku oil pool
LBL
NASA
• The remaining organic
carbon is stored in forms
not presently economic to
retrieve
The Terrestrial Solar Collector
Land plant density proportional to rainfall
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7/21/2014
1st Generation Geofuels
Coal (19th Century)
Cypress swamp
•
•
•
•
•
Swamp fire
Peat
Remains of land plants
Easy to find
Relatively abundant
Need to dig it up
Relatively dirty to extract
and burn
Coal
The Marine Solar Collector
Phytoplankton = one celled aquatic plants
Marine productivity highest near continents
Open oceans not trapping solar energy
NASA
Shale
Mancos Shale, CO
• Starts as mud, with layers
of organic matter
UW SSEC
Green River Shale, WY
• Source rock for petroleum
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7/21/2014
Sediment Thickness - Km
(Laske and
Masters,1997)
• Thick area of sedimentary rocks
• Includes oil source rocks, oil fields in “Silurian” rocks
• Also major salt accumulations
• Average geothermal gradient 25°C/km (range 10-50°C/km)
• Oil and gas generation typically in range of 90-200°C
• Also depends on heating rate
Sandstone Porosity
• Holes in rock, where oil/gas can reside
• Typical range in conventional oilfields ~10-30%
• Provides avenues for fluid flow (permeability)
Above: UC Berkeley Oil
Consortium, Tad W. Patzek
Petroleum Migration
Sandstone
Stream channel
USGS
Triassic river-deposited sandstone in central China
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2nd Generation Geofuels
Conventional Oil and Gas (20th C.)
HUBBERT’S PREDICTIONS
U.S. Oil Production
• Generated primarily from aquatic
plants (algae)
• Naturally concentrated
• Often challenging to find
• Relatively easy to extract
• Peak oil concerns?
Gas
Oil
Water
Houston Geological
Society, 2003
Beyond Peak Oil
• U.S. oil production has recently reversed its decline and now heading upward!
• Predictions for the future increasingly divergent from Hubbert model
World Oil Production
• Peak around 1970 correctly predicted
• Actual production in 2000 higher than predicted
World Peak Oil?
Despite many predictions, no sign of peak just yet…
Reserves
The known amount of a commodity that
can be profitably extracted, assuming
present day technology and economic
conditions.
Resources
Reserves that have not yet been
discovered or are not yet economic (or
both)
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7/21/2014
Proven U.S. Crude Oil Reserves
(Data source: EIA)
Proven (?) World Crude Oil Reserves
(Data source: Oil and Gas Journal)
Exploration for New Fields
North Slope of Alaska
Discoveries Peaked in 1970s-80s
3D Seismic
Steve Holbrook
Reserves Growth
Midway-Sunset Field, California
Tennyson, 2005
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7/21/2014
An Agricultural Analogy
3rd Generation Geofuels
Unconventional Oil and Gas
(21st
C.)
• Disseminated in low-permeability
reservoirs
• Abundant, easy to find
• More difficult to extract (hydraulic
fracturing)
Wiki Commons
• Corn in field is analogous to disseminated shale gas
• Corn in elevators is analogous to conventional gas
field; it has been concentrated in one place
• Corn may be obtained from elevator by opening a
chute, but corn in field requires harvesting
Shale
Sandstone
Tuban Shale, Indonesia
Alan Carroll 2011
• Impermeable rock made of mud; tends to
impede the flow of oil, gas
• Most abundant sedimentary rock type
Shale Gas
Gas that occurs in microscale pores in shale
(10-6
m) to nano-
Mudstone
500 Million Years
of Sunlight
(10-9 m)
The Resource Pyramid
Total
Geologic
Carbon Burial
in Earth’s Crust
S. Sonnenberg
Economic Geofuels (coal, oil gas) =
1 Week of Sunlight
~100 years of sunlight
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Hydraulic Fracturing
U.S. Oil and Gas Price History
12
10
8
Natural Gas Wellhead Price
(dollars per 1000 cu. Ft.)
6
1999
4
2
0
150
100
West Texas Intermediate Crude
(dollars per barrel)
50
2003
0
Hydraulic Fracturing
• Pumps create
pressure >
failure strength
of rock
• Fractures are
propped open
with sand
(called
“proppant)
• Frac fluids also
include
chemicals
such as HCl,
meant to
stimulate
production
Wisconsin
Frac Sand
WGNHS
R. Dott
R. Dott
(Kent Perry, GTI, 2006)
U.S. currently largest producer
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Bakken Formation
USGS
“Oreo cookie” geology: short-distance migration of
oil from two shale intervals into middle sandstone
U.S. Natural Gas Reserves History (EIA)
350
Reserves = proven economic by drilling
Assessment = recoverable with present technology
300
250
200
150
Trillion
Cubic
Feet
(TCF)
• 300 TCF = 12 years supply at present consumption
Data: EIA
• Domestic oil and gas production both increasing
since 2005
• USGS assessment 694 TCF “continuous” gas, 410
TCF conventional gas (2012)
100
• Total assessed = 45 years at present consumption
50
• Ultimate resource magnitude still unknown?
0
• Driven by increased oil, gas prices
Alan Carroll 2011
Environmental Impact?
NETL
S. Sonnenberg
Impact on landscape, surface water, neighbors?
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Drilling Density
NASA
Impact on Freshwater Aquifers?
Safety of Frac Fluids?
NETL
NETL
• Millions of gallons per “frac job”
• Mostly water, but includes other chemicals
Schematic: Subsurface Gas Leakage
Fractures usually thousands of feet below aquifers
How Much
Is Out There?
• Key question: how
long will economic
resources last?
• Answer requires
knowledge of future
prices and technology
(which we can’t
actually know)
• Total magnitude of
fossil fuels and
uranium very large
Alan Carroll 2011
(Data sources include the the BP Statistical
Review of World Energy, the U.S. Geological
Survey, Cleveland et al., 1984, Gupta and Hall,
2011, Rogner et al., 2013, Sell et al., 2011)
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7/21/2014
Conclusions
• Quality, not quantity
Recent increase in U.S. oil and gas coming (in part) from
large but relatively low-quality reserves. Likely to be more
expensive in the long run?
Prediction is Hard
“It ain't what you don't know that gets you into
trouble. It's what you know for sure, that just
ain't so.”
Mark Twain
• Technology changes reality
Impact of new unconventional reserves was entirely
unanticipated 10-15 years ago! Replacement of coal is
driving unexpected reduction in CO2 emissions.
• There’s no free lunch
Lower permeability reservoirs inevitably require higherdensity drilling, with attendant environmental problems.
“Prediction is very difficult,
especially about the future”
Attributed to Niels Bohr
(Also attributed to Yogi Berra)
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