Shale Gas
Resources of Utah: Assessment of
Previously Undeveloped Gas Discoveries
Schamel, Steven1 (1)
GeoX Consulting Inc, Salt Lake City, UT
A survey of archived drilling records
demonstrates that significant quantities of natural gas have been discovered in
the Mancos Shale across a broad area of the southern Uinta basin, northeast Utah. The impediments to
previous production of this gas have been unfavorable market conditions and the
inadequate fracture stimulation technology employed. Until recently, it was
standard practice to use the same light gel, KCL-foam and acid fracture
stimulations that were employed in the sandstone reservoir objectives.
Undoubtedly, these caused more damage to the shales
than if the interval had not been stimulated. Favorable gas tests from Mancos
Shale completions, good DSTs, large to very large mud
gas readings, and widespread gas shows all demonstrate the strong potential for
development of this shale gas reservoir. Whereas most of the good indications
are in the upper part of the 3,000-3,5000 ft thick
Mancos Shale, principally in the Prairie Canyon Member, favorable indications
are found in all of the other shaly and silty units, the Blue Gate, Juana Lopez and Tununk Members. At present, Mancos shale gas is being
produced from a small number of wells in the Flat Rock and Greater Natural
Buttes fields. In most instances, this is “add-on” gas, supplementing
production from conventional sandstone reservoirs. No wells were identified
that adequately tested the shale gas potential of the Hermosa Group black shales in the Paradox basin of Utah, but other indications
are good that this also is a potentially large shale gas resource waiting to be
discovered and developed.