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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Coalbed Methane Exploration Concepts — Where is the Next Big Play?
By
Altuda Energy Corporation
San Antonio, Texas
Natural gas prices are expected to remain relatively high over
the next two to five years and these higher gas prices have
turned coalbed into one of the most active gas plays in the
United States. Coalbed methane (CBM)
is an important part of the natural gas
supply for the United States and now
represents more than 7 percent
of total
gas production and 7
percent
of dry gas
proved reserves—and these values are
expected to increase. Everyone asks
where the next big San Juan Basin-scale
CBM play will be in the United States. The simple answer is that
the San Juan Basin (SJB) is unique and there will not be another
“perfect CBM play.” But all basins share characteristics with the
SJB and following proven exploration concepts can minimize
risk in any coal-bearing basin.
Over the past decade, hydrogeologic evaluation and comparison
of coal basins in the United States and internationally indicates
that depositional systems and coal distribution, coal rank, gas
content, permeability, hydrodynamics and tectonic/structural
setting are critical controls on coalbed methane producibility. A
dynamic interplay among these controls determines high coalbed
methane productivity and the absence of one or more of these
factors
will result in lower coalbed methane production. Where is
the next coalbed methane play? The most prospective drilling
locations will be in areas of upward flow potential in the presence
of thermally mature coals that have reached the threshold of
thermogenic gas generation, and/or where secondary biogenic
gas generation has occurred. A regional understanding of hydrogeology
to delineate sweet-spots and an accurate economic
evaluation of the prospect are critical to project success.
Of equal importance are the economic aspects of any hydrogeologic- based play. Accurate determination of land acquisition and drilling costs water disposal methodology, pipeline gathering system costs, and future gas prices on a local and regional scale must also considered. Enhanced recovery techniques such a nitrogen and carbon dioxide injection will ultimately recover more CBM resources and some deeper coal beds may prove exploitable. An emerging technology that utilizes microbes to stimulate or enhance CBM production through the in situ bioconversion of coal or sequestered carbon dioxide potentially may result in CBM production in areas that are currently uneconomical. If this technology is successful maybe the correct answer to “Where is the next big CBM play?” should be both “nowhere” and “everywhere”.
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