|
National - Shale Gas an Essential Component of the Nation's Future
By David Coffman, Vice-President, Marketing, GDF SUEZ Energy Resources NA
One of the more significant issues to
surface in the ongoing U.S. energy policy debate is the
emergence – and importance – of shale formations as
a key
source of natural gas.
Although shale gas production
dates back to the 1820s, advances in horizontal drilling and
hydraulic fracturing have dramatically increased its potential.
This has provided the country with a vital weapon in the fight
for energy independence, while at the same time putting a
legislative, regulatory, and political spotlight on the
processes by which the gas is extracted.
In that by some
estimates these shale “plays” have enough recoverable resources
to meet U.S. natural gas needs for 116 years, the nation’s
ability to successfully manage concerns related to production
will have a major impact on the direction of the American energy
future.
A New Land Rush
Shale gas
has always been a part of the domestic production landscape. In
1821, the first shale gas well was drilled in Fredonia, New
York, and activity continued until 1859, when the volume from
conventional gas reservoirs substantially overtook that from the
hard, non-porous rock formations.
Production continued
into the 20th century, as geologists and wildcatters looked for
better, more economical ways to maximize the potential of
gas-bearing shale. When they eventually found the right drilling
technique – and rising natural gas prices made those processes
commercially viable – a “land rush” that had been slow getting
out of the starting gate prior to the 1980s suddenly took off.
Gas-rich shale plays span the country, from New York to
Texas, Montana to Alabama. But for the most part, attention has
largely concentrated on four primary formations: Barnett, in the
Fort Worth Basin of North-Central Texas; Fayetteville, in
Northern Arkansas and Eastern Oklahoma; Haynesville, in Northern
Louisiana and Eastern Texas; and Marcellus, which spans six
states and extends from parts of Tennessee into Southern New
York.
Barnett Shale
“The source of America’s (energy) transformation lies in the
Barnett Shale,” writes The Economist. More than 10,000 wells
have been drilled in the 5,000-square-mile formation, whose
natural gas content – 300 to 350 standard cubic feet per ton –
is among the highest of any play in North America. With an
estimated 327 trillion cubic feet of gas and 44 trillion cubic
feet of technically recoverable resources, the Barnett Shale
today accounts for 7 percent of U.S. natural gas supplies.
Fayetteville Shale
The Fayetteville play is roughly double the size of Barnett,
though the gas content of 60 to 220 standard cubic feet per ton
is smaller. However, production in the region has accelerated
significantly in recent years, increasing from 13 wells in 2004
to more than 1,000 today, making it “one of the most active
plays in the U.S.,” according to the Department of Energy.
Fayetteville has an estimated 52 trillion cubic feet of gas,
with 41.6 trillion cubic feet of technically recoverable
resources.
Haynesville Shale
Haynesville emerged in 2007 as a potentially significant source
of shale gas. Although it may take a few years to determine the
play’s true development possibilities, estimates of the
formation’s gas content are as high as 330 standard cubic feet
per ton – up in the Barnett Shale range. Moreover, Haynesville’s
estimated 251 trillion cubic feet of technically recoverable
resources is more than five times that of the Texas play.
Marcellus
Right now,
this is where much of the U.S. shale gas activity is
concentrated. The most expansive play in the country, it covers
96,000 square miles. When drilling began in the early 2000s,
estimates were that the formation held 1.9 trillion cubic feet
of gas. Further study pushed that projection to 500 trillion
cubic feet. More recent estimates put the potential at 1,500
trillion cubic feet, of which 262 trillion are recoverable, and
it is widely expected that those figures will be further
adjusted upward. According to one study, Marcellus may contain
2,445 trillion cubic feet of reserves in place and has the
potential to yield the equivalent of a 20-year supply of natural
gas for the country.
Proven Technologies
Facilitate Development
There is no question that
the combination of two oilfield techniques – horizontal drilling
and hydraulic fracturing – has opened the door of opportunity
for shale gas development. Along with the economies of scale
that followed greater exploration and extraction, The Economist
reports, “improvements in techniques have halved the production
costs of shale gas, making it cheaper even than some
conventional sources.”
In the hydraulic fracturing
process, a liquid composed primarily of sand and water is pumped
into the shale formation, causing cracks or fractures. Generally
used in formations deep below the earth’s surface (5,000 to
20,000 feet down) that have low porosity and permeability, it
helps create a path that allows trapped natural gas to flow up
the borehole for recovery. The ability to use horizontal
drilling techniques – in which a bit is inserted vertically and
then curves horizontally, allowing for multiple fractures and
multiple wells from a single platform – further optimizes
production.
Interestingly, for all of the recent news
media attention that has focused on hydraulic fracturing, the
process is hardly new. It was used in industrial operations as
early as 1903 and was introduced to oil and gas production in
1949. Currently a mainstay of the global energy industry,
hydraulic fracturing has been used to stimulate more than 1
million wells in the United States; 90 percent of U.S. natural
gas wells rely on fracturing.
Concerns Over Water
With the increased awareness of shale oil
development, there has been a parallel increase in the
visibility of fracturing. Predictably, the added scrutiny has
raised concerns, most of them related to the environment.
The core issue is the content of the so-called “fracking
liquid” pumped into the rock and whether it can contaminate
water supplies. Although specific compounds used in specific
operations can vary, for the most part the fluids are 99.5
percent fresh water. The Department of Energy explains:
"The fracturing fluids used for gas shale stimulations
consist primarily of water but also include a variety of
additives…A typical fracture treatment will use very low
concentrations of between 3 and 12 additive chemicals depending
on the characteristics of the water and the shale formation
being fractured."
Critics have pointed to a handful
of incidents in which they suggest fracturing has tainted the
local water resources. But independent investigations have never
been able to link the incidents in question to fracking fluids,
and past studies by the U.S. Environmental Protection Agency and
the Ground Water Protection Council have concluded the process
possesses no risk.
However, the EPA recently undertook a
new study to determine if fracturing poses a danger to human
health and water quality. Also, legislation is pending in
Congress that would bring hydraulic fracturing under the
regulatory umbrella of the Safe Drinking Water Act rather than
leave oversight to the states alone.
Vast
Potential
Although the techniques by which
natural gas is developed from shale may be up for debate, there
is no question that unconventional plays will have an enormous
role in the U.S. energy future.
An estimated 385
trillion cubic feet of technically recoverable natural gas
exists in the lower 48 U.S. states, and the consulting firm ICF
forecasts that unconventional shale gas production – which also
includes tight gas and coalbed methane – will increase from 42
percent of total U.S. production in 2007 to 64 percent in 2020.
A March 2010 IHS Cambridge Energy Research Associates report
calls shale gas a potential “game changer.”
Of course,
none of this factors in the environmental benefits of natural
gas, which is the cleanest of all fossil fuels and results in
reduced greenhouse gas emissions. So if concerns over process
can be objectively assessed and addressed, it is clear that
natural gas from unconventional sources will likely be an
essential component of the nation’s future strategies for
environmental, energy, and national security.
Back to Articles
|
