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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Sequence Stratigraphic and Facies Architecture of the Cotton Valley
Lime/Haynesville of the East Texas Salt Basin
By
Recent advances in high-resolution sequence stratigraphy of carbonate ramp systems enhance our understanding of the Upper Jurassic stratigraphy of the East Texas Salt Basin (ETSB). The ETSB is enjoying a revival via the recent Cotton Valley Lime (CVL) "pinnacle reef' play. This play complements the existing traditional CVL/Haynesville "oolite shoal" play type. Consideration of Gulf of Mexico (GOM) regional Mesozoic sequence stratigraphy and paleogeography aids in linking the two play types together in an integrated chronostratigraphic framework, thus providing some predictive capability for reservoir distribution and reservoir quality. Although currently perceived as a 3-D seismic play, regional sequence stratigraphic analysis assists greatly in locating favorable trends and high-grading existing opportunities.
The Middle Jurassic-Lower Cretaceous stratigraphy of the GOM consists of five major second-order (approximately 15 m yr duration) supersequences, defined as large regionally correlative, retro gradational- aggradational/progradational accomodation packages. Each exhibits systematic vertical/lateral stacking patterns of subordinate third-order sequences (1-3 myr duration) and component lateral/vertical facies and systems tracts. The five supersequences are: Supersequence 1 (SS 1) - Upper Bathonian to Lower Kimmeridgian (158.5 - 144 mya); SS 2 - Lower Kimmeridgian to Berriasian (144 - 128.5 mya); SS 3 - Upper Valanginian to Lower Aptian (128.5 - 112 mya); SS 4 - Lower Aptian to Upper Albian (112 - 98 mya); and SS 5 - Upper Albian to Santonian (98 - 84 mya).
The Upper Jurassic Smackover-Buckner-
CVL-Bossier formational stratigraphy
makes up part of SS 1 and SS 2. The
Smackover represents the second-order,
late transgressive systems tract (TST) and
highstand systems tract (HST) of SS 1; the
Buckner evaporite/red bed
facies depicts
latest HST conditions of SS 1 and lowstand
systems tract (LST) development of SS 2.
The Haynesville/Cotton Valley Lime paired
ramp-shoal carbonate and offshore detached
"pinnacle" facies marks the second-order
TST of SS 2, and the overlying
Bossier equates to the second-order interval
of maximum flooding.
Within the above framework, Smackover-
Buckner carbonate-evaporite facies tracts
consist of several regionally correlative
third-order sequences (250-350 ft. thick on
average; 1 ma duration on average) that
systematically stack in a progradational
fashion throughout the ETSB. In detail,
each successive sequence is thinner than the
underlying one, and each is progressively
enriched in "blocky" highstand carbonates,
plus proximal evaporite-red bed
sequences.
The "144" ma supersequence boundary
marks a zone of minimum second-order
accomodation (a point of stratigraphic
"turnaround") and serves as a regional
stratigraphic datum useful for hanging well-log
cross-sections. Above this horizon,
Haynesville/CVL sequences stack as a series
of retrogradational third-order sequences
(each approximately 50 to 150 ft.
thick; approx. 1 ma in duration). Each sequence contains an updip, proximal evaporite-
red
bed
facies, a ramp-margin "oolite
shoal" belt (traditional Haynesville reservoirs),
and a paired downdip "pinnacle
reef' facies stranded in the overall second-order
TST of SS 2. Regionally, several sequences
of third-order TST and ST are recognized,
and updip "oolite shoals" reservoirs
can be correlated directly with time-equivalent
"pinnacle reef" reservoirs, thus
casting light on mechanisms for porosity
development. The top of the CVL/Haynesville carbonate is a diachronous surface
characterized by appreciable depositional
topography, onlapped by the Bossier
shale along a well-documented submarine
condensed section. Little evidence exists for
a significant relative sea-level drop at this
surface.
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