Utica Shale - The Natural Gas Giant Below the Marcellus?
Stacked plays in the Appalachian Basin produce multiple natural gas pay zones.
The Marcellus was the Opening Act
A rock layer below the Marcellus Shale is developing into another incredible source of natural gas.
The Marcellus Shale captured public attention when leasing and drilling activities began pumping billions of
dollars into local economies and citizens began debating the environmental, social and economic impacts. All
of this began suddenly in 2004 when Range Resources Corporation drilled the first Marcellus well using modern
drilling technology.
Now, just a few years later, the Marcellus Shale is being developed into one of the world's largest natural gas fields.
However, what we are seeing today from the Marcellus is only the first step in a sequence of natural gas plays.
The second step is starting in the Utica Shale.
What is the Utica Shale?
The Utica Shale is a rock unit located a few thousand feet below the Marcellus Shale. It also has the potential to become an enormous natural
gas resource. The Utica Shale is thicker than the Marcellus, it is more geographically extensive and it has already proven its
ability to support commercial production.
It is impossible to say at this time how large the Utica Shale resource might be because it has not been thoroughly
evaluated and little public information is available about its organic content, the
thickness of organic-rich intervals and how it will respond to horizontal drilling and hydraulic fracturing. However,
the results of early testing indicate that the Utica Shale will be a very significant resource.
Where is the Utica Shale?
The potential source rock portion of the Utica Shale is extensive. In the United States it underlies portions of
Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, West Virginia and Virginia. It is also present
beneath parts of Lake Ontario, Lake Erie and part of Ontario, Canada. This geographic extent of potential Utica Shale
source rock is shown on the map labeled as Figure 1 in the right column of this page.
If the Utica is commercial throughout this extent it will be geographically larger than any natural gas field known today.
The Utica Shale is much deeper than the Marcellus. The Utica Shale elevation map shown as Figure 2 in the right column of this page
has contour lines that show the elevation of
the base of the Utica Shale in feet below sea level. In some parts of Pennsylvania the Utica Shale can be over two miles
below sea level. However, the depth of the Utica Shale decreases to the west into Ohio and to the northwest
under the Great Lakes and into Canada. In these areas the Utica Shale rises to less than 2000 feet below sea level. Beyond the potential source rock areas the Utica Shale rises to Earth's surface and can be seen in outcrop. An outcrop photo of the Utica Shale near the town of Donnaconna, Quebec, Canada is show in the right column of this page as Figure 3.
Most of the major rock units in the Appalachian Basin are thickest in the east and thin towards the west.
The rock units that occur between the Marcellus Shale and the Utica Shale follow this trend. In central Pennsylvania,
the Utica can be up to 7000 feet below the Marcellus Shale but that depth difference decreases to the west.
In eastern Ohio the Utica can be less than 3000 feet below the Marcellus.
These depth relationships of the Utica Shale and the Marcellus Shale are shown in the generalized cross
sections shown below as Figure 4a and Figure 4b.
Figure 4a: The cross-section above shows the subsurface position of the Marcellus Shale, Utica Shale and the continental basement rock. The line of cross section is shown as line A-B on the inset map. Note that the Utica Shale is about 2000 feet below the Marcellus under eastern Ohio but about 6000 feet below the Marcellus in southcentral Pennsylvania. Also note that the Marcellus Shale potential source rock does not extend as far into Ohio as the Utica.
This cross-section was compiled by Geology.com using data provided by the Energy Information Administration [1], the United States Geological Survey [2], the Pennsylvania Geological Survey [3], and the U.S. Department of Energy [4].
Figure 4b: The cross-section above shows the subsurface position of the Marcellus Shale, Utica Shale and the continental basement rock. The line of cross section is shown as line A-B on the inset map. Note that the Utica Shale is about 1800 feet below the Marcellus under western New York but about 5000 feet below the Marcellus in southcentral Pennsylvania. Also note that the Marcellus Shale potential source rock does not extend as far into New York as the Utica.
This cross-section was compiled by Geology.com using data provided by the Energy Information Administration [1], the United States Geological Survey [2], the Pennsylvania Geological Survey [3], and the U.S. Department of Energy [4].
Development of the Utica Shale Gas Play
In early 2011, most of the mineral rights leasing and drilling activity tied directly to the Utica Shale were in eastern Ohio and Ontario, Canada. In these areas the Utica Shale is less than 4000 feet below the surface and the Marcellus Shale is not present. (If the Marcellus is present it becomes the target
because it is shallower, less expensive to drill and has a proven potential.)
The generalized cross-section for the Utica and Marcellus Shale shown above as Figure 4
illustrates why the Utica is being developed in some parts of the Ohio and Canada instead of the Marcellus.
Where Cross-Section 4a traverses the Pennsylvania-Ohio state boundary the Marcellus Shale is above the Utica and would be
preferentially drilled because it is a shallower target. However, the productive portion of the
Marcellus Shale does not extend into central Ohio - but the Utica Shale does. In those areas
the Utica Shale is less than one mile below the surface and a few companies are leasing and
drilling the Utica Shale for natural gas.
Utica Shale in Eastern Ohio
During 2011 most of the drilling activity in the Utica shale was occurring in eastern Ohio. This geographic area
attracted interest for a variety of reasons which include: 1) the Utica Shale is only a few to several thousand
feet below the surface; 2) lease prices had not yet been driven up to competitive levels; and, 3) early wells
drilled into the Utica Shale were yielding significant amounts of natural gas liquids - which can significantly
increase the value of a well. During 2011 natural gas companies spent billions of dollars acquiring Utica Shale
acreage in eastern Ohio.
The Utica Shale is proving to be rich in oil and natural gas liquids. On an energy-equivalent basis they are
worth significantly more than natural gas. The Ohio Department of Natural Resources estimates a recoverable
Utica Shale potential between 1.3 and 5.5 billion barrels of oil and between 3.8 and 15.7 trillion cubic
feet of natural gas. Companies interested in drilling the Utica Shale are swamping ODNR with permit applications
(see chart at right). [13]
Press releases from Chesapeake Energy reported several wells with peak rates of over five million cubic feet of natural gas
per day along with hundreds to thousands of barrels of natural gas liquids. Optimism based upon these drilling results
prompted Chesapeake to claim that their Utica Shale assets added over $15 billion in value to the company.
Having achieved successful results from recent drilling activities in eastern Ohio, Chesapeake is announcing the discovery of a major new liquids-rich play in the Utica Shale. Based on its proprietary geoscientific, petrophysical and engineering research during the past two years and the results of six horizontal and nine vertical wells it has drilled, Chesapeake believes that its industry-leading 1.25 million net leasehold acres in the Utica Shale play could be worth $15 - $20 billion in increased value to the company.[12]
As part of a $3.4 billion transaction between Chesapeake Energy, EnerVest and an unnamed foreign company, John Walker, CEO of EnerVest, claims that Utica Shale formation assets in ten counties of eastern Ohio were valued at about $15,000 per acre. [13]
The Utica Shale is an organic-rich calcareous black shale that was deposited about 440 to 460 million years ago
during the Late Ordovician. It overlies the Trenton Limestone
and is a few thousand feet below the Marcellus Shale (see the generalized stratigraphic column shown as Figure 5 in the right column of this page).
The Utica Shale has a much higher carbonate content than the Marcellus Shale and a lower clay mineral content.
This difference in mineralogy produces a very different response to hydraulic fracturing treatments. The methods
used in the Marcellus do not produce as much fracturing in the Utica. However, future research might be able to significantly improve the
fracturing rate. (In Texas, the Eagle Ford Shale also has a high carbonate content.
Drillers there have discovered ways to make the brittle carbonate zones fracture at a much higher rate than other gas shale rock units.)
The clastic rock units of the Appalachian Basin are generally thickest in the eastern part of their extent and thin towards the
west. That generalization holds for the rock units between the Utica Shale and the Marcellus Shale. In Central Ohio the Utica
Shale is less than 3000 feet below the Marcellus Shale and in central Pennsylvania the Utica
Shale can be up to 7000 feet below the Marcellus (see the cross-section above labeled as Figure 4 for a visual of this concept).
Thickness of the Utica Shale
The thickness of the Utica Shale is variable. Throughout the potential source rock area it ranges in thickness
from less than 100 feet to over 500 feet. Over the rock unit as a whole there is a general thinning from east to
west. A thickness map of the Utica Shale is shown as Figure 5 in the right
column of this page. Although thickness of a reservoir rock can be important, the organic content and presence of
gas are what determines the true potential of a gas shale. Very little public information is available on the organic
content of the Utica shale.
Future Development of the Utica Shale
Two important challenges for developing the Utica Shale are its significant depth and a lack of information.
In areas where the Marcellus Shale is present the Utica Shale is probably going to be a resource of the distant future.
The Marcellus Shale is less expensive to develop and companies will focus on it before setting their sights on
a deeper target with an uncertain payoff.
However, in areas where the Marcellus Shale has been developed the Utica will have an infrastructure advantage. Drilling pads, roadways, pipelines,
gathering systems, surveying work, permit preparation data and landowner relationships might still be useful for developing the Utica Shale.
In areas beyond the Marcellus Shale the Utica has already become
a primary target. Leasing and drilling are already occurring in eastern Ohio and Ontario, Canada
with some wells capable of yielding commercial quantities of gas.
How Will the Utica Shale Be Drilled?
The Utica Shale is an unconventional reservoir like the Marcellus Shale. The rock unit can have significant
porosity; however, the pore spaces are so small that natural gas has a difficult time flowing through
them. Large amounts of gas is also adsorbed onto mineral material within the rock unit.
The most likely methods to be used will be horizontal drilling with
hydraulic fracturing.
The Utica Shale underlies parts of Lake Erie and Lake Ontario. Perhaps offshore drilling will occur there at some future date.
Video Interview: Potential of Other Gas Shale Formations in the Northeastern United States, Pennsylvania State University geologist Dr. Terry Engelder describes historical and recent drilling results for the Utica Shale.
Figure 1: The green area on this map marks the geographic extent of what is suspected to be Utica Shale source rock. This is the portion of the Utica Formation that geologists believe has the potential to yield natural gas. It is beneath several US states, part of Lake Erie, part of Lake Ontario and part of Ontario, Canada.
If developed to this full potential the Utica Shale gas play will be larger than any natural gas field known today.
The thin yellow line on the map outlines the geographic extent of the Marcellus Shale Gas Play. This map clearly demonstrates
that the Utica Shale has a geographic extent that is much greater than the Marcellus Shale play.
This map was compiled by Geology.com using data provided by the Energy Information Administration [1] and the United States Geological Survey [2].
Figure 2: Approximate elevation for the base of the Utica Shale (top of the Trenton). Elevations shown on the map are feet below sea level.
This map was compiled by Geology.com using data provided by the Energy Information Administration [1], the United States Geological Survey [2], and the Pennsylvania Geological Survey [3].
Figure 3: Photograph of the Utica Shale near the town of Donnaconna, Quebec, Canada. Dark beds are shale, light beds are limestone. Part of the dark color in the Utica Shale comes from organic matter. A writing pen is shown for scale. Image and caption by The National Energy Board of Canada; from A Primer for Understanding Canadian Shale Gas.
Figure 5: Generalized stratigraphic sequence of rock units surrounding the Utica Shale and Marcellus Shale. The Utica and Marcellus are so geographically extensive that it is impossible to present a stratigraphic sequence that would be correct in all areas. This diagram presents a generalized sequence of rocks that might be present in the central portion of the Utica Shale Play. Image by Geology.com.
Figure 6: Thickness map of rocks present between the top of the Trenton/Black River Groups and the top of the Utica Shale. In some areas the Point Pleasant Shale and the Antes Shale are included in this thickness.
This map was compiled by Geology.com using data provided by the Energy Information Administration [1],and the U.S. Department of Energy [4].
Figure 7: Utica Shale drilling permits issued in Ohio during 2011. Chart by the Energy Information Administration using data from the Ohio Department of Natural Resources. [14]
[3] The Geology of Pennsylvania, Charles H. Schultz, editor; Pennsylvania Geological Survey, Special Publication 1, 1999, 888 pages.
[4] Source Rock Distribution and Total Organic Carbon Content; From: Patchen, D.G., and others, 2006, A geologic play book for Trenton-Black River Appalachian Basin exploration: Final report prepared for U.S. Department of Energy, contract no. DE-FC26-03NT41856.
