WASHINGTON, DC -
The Powder River Basin, a vast region of high plains in Wyoming and Montana
known for producing low-sulfur coal, is also becoming a primary source
of America's fastest growing natural gas resource, coalbed methane.
Now, a new Department of Energy report projects that the region may hold
more coalbed methane than previously estimated but the amount that will
actually be produced will depend largely on the choice of the water disposal
The study, Powder River Basin Coalbed Methane Development and Produced
Water Management Study, was prepared by Advanced Resources International
of Arlington, VA. The Energy Department's Office of Fossil Energy commissioned
the study through its National Energy Technology Laboratory to help federal
and state agencies plan for future development of this significant natural
The study found that discharging water produced during coalbed methane
operations into rivers and streams – a practice currently allowed
by state permits since the quality of the water is generally as good as
normal drinking water – is the lowest cost option and results in
the largest estimates of economically recoverable gas.
|Powder River CBM Production
The Powder River Basin is the site of
the nation's fastest growing domestic natural gas play -- the development
of coalbed methane (CBM).
The report concludes that more than 29 trillion cubic feet (Tcf) –
or nearly 75 percent of the 39 Tcf of technically recoverable gas estimated
in the study – could be economically produced with the surface discharge
disposal method at the study's assumed gas prices. The study did not assess
the amount of produced water that would meet state permitting standards
for this type of disposal; so, actual producible quantities of coalbed
methane might be somewhat less.
Constructing infiltration impoundment ponds with associated evaporation
equipment would be the next most economically attractive water disposal
option, the study found, potentially resulting in 28 Tcf of economically
Re-injecting the water into shallow fresh water zones – a method
that has only limited success to day – could likely lead to about
27 Tcf of economically recoverable gas, while treating the produced water
with a process called "reverse osmosis" would cut the amount
of economical gas to around 18 to 22 Tcf.
Deep reinjection of the produced water was not included among the disposal
alternatives studied because it is likely to be significantly more expensive,
and many experts believe that it constitutes a loss of a valuable resource
for the arid West.
In each of the study's cases, the amount of natural gas potentially producible
from Powder River coal seams could be a valuable addition to the nation's
energy supplies. The study's 39 Tcf estimate of technically-recoverable
reserves is among the highest of a range of resource estimates for the
Powder River Basin from Federal, State, and industry organizations. Because
of differences in methodologies, geologic models, and assumptions, other
current estimates vary greatly, in some cases by a factor of five, ranging
as low as 8 Tcf.
Currently, throughout the lower 48 states, proven reserves of all natural
gas supplies amount to just over 180 Tcf. About 22 Tcf of natural gas
are consumed by Americans each year.
Nearly 4 billion cubic feet per day of coalbed methane is currently being
produced in the United States, with about 20 percent of it coming from
the Powder River Basin. Within the next 10 years, however, as much as
75 percent of the growth in coalbed methane production is expected to
occur in this region. As many as 39,000 new coalbed methane wells could
be drilled in the Powder River Basin during the next decade, compared
to the 9,000 coalbed methane wells operating today.
The new DOE study also concludes that future coalbed methane operations
will require fewer wells than previously estimated by other studies and
that the amount of water associated with coalbed methane production in
the Powder River Basin may be substantially less than the studies estimated.
The U.S. Department of the Interior's Bureau of Land Management and the
U.S. Environmental Protection Agency, along with several state agencies,
cooperated with the Energy Department on the study. The complete report
is available on-line at the National Energy Technology Center's Strategic
Center for Natural Gas website at
http://www.netl.doe.gov/technologies/oil-gas/index.html. The report
is also available on CD.
The study is one of several being sponsored
by the Energy Department that examine the issues surrounding coalbed methane
development. Others include development of best management practices,
electronic mapping of environmental and well data, a coalbed methane primer
for the public, a handbook for the development and review of environmental
documents required for coalbed methane projects, analysis of the options
for beneficial use of coalbed methane produced water, and research on
technologies for produced water treatment.