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Description:
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Gas production from low -permeability (tight ) gas sandstones is increasingly important in
the USA as conventional gas reservoirs are being depleted , and its importance will
increase worldwide in future decades . Travis Peak tight sandstones have produced gas
since the 1940s . In this study , well log , 2D seismic , core , and production data were used
to evaluate the geologic setting and reservoir characteristics of the Travis Peak
formation . The primary objective was to assess the potential for basinward extension of
Travis Peak gas production along the west margin of the East Texas Basin .
Along the west margin of the East Texas Basin , southeast -trending Travis Peak
sandstones belts were deposited by the Ancestral Red River fluvial -deltaic system . The
sandstones are fine -grained , moderately well sorted , subangular to subrounded , quartz
arenites and subarkoses ; reservoir quality decreases with depth , primarily due to
diagenetic quartz overgrowths . Evaluation of drilling mud densities suggests that strata
deeper than 12 ,500 ft may be overpressured . Assessment of the geothermal gradient
(1 .6 °F /100 ft ) indicates that overpressure may be relict , resulting from hydrocarbon
generation by Smackover and Bossier formation potential source rocks . In the study area , Travis Peak cumulative gas production was 1 .43 trillion cubic feet
from January 1 , 1961 , through December 31 , 2005 . Mean daily gas production from 923
wells was 925 ,000 cubic ft /well /day , during the best year of production . The number of
Travis Peak gas wells in “high -cost” (tight sandstone ) fields increased from 18 in the
decade 1966 -75 to 333 in the decade 1996 -2005 , when high -cost fields accounted for
33 .2 % of the Travis Peak gas production . However , 2005 gas production from high cost
fields accounted for 63 .2 % of the Travis Peak total production , indicating that
production from high -cost gas wells has increased markedly .
Along the west margin of the East Texas Basin , hydrocarbon occurs in structural ,
stratigraphic , and combination traps associated with salt deformation . Downdip
extension of Travis Peak production will depend on the (1 ) burial history and diagenesis ,
(2 ) reservoir sedimentary facies , and (3 ) structural setting . Potential Travis Peak
hydrocarbon plays include : updip pinch -outs of sandstones ; sandstone pinch -outs at
margins of salt -withdrawal basins ; domal traps above salt structures ; and deepwater
sands . |