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Use of novel high-resolution 3D marine seismic technology to evaluate Quaternary fluvial valley development and geologic controls on shallow gas distribution, inner shelf, Gulf of Mexico

Timothy A. Meckel and Francis J. Mulcahy
Use of novel high-resolution 3D marine seismic technology to evaluate Quaternary fluvial valley development and geologic controls on shallow gas distribution, inner shelf, Gulf of Mexico
Interpretation (Tulsa) (February 2016) 4 (1): SC35-SC49

Abstract

The first deployment of the P-Cable (super TM) high-resolution 3D (HR3D) seismic acquisition system in the Gulf of Mexico has provided unprecedented resolution of depositional, architectural, and structural features related to relative sea-level change recorded in the Quaternary stratigraphy. These details are typically beyond conventional 3D seismic resolution and/or excluded from commercial surveys, which are generally optimized for deeper targets. Such HR3D data are valuable for detailed studies of reservoir analogs, sediment delivery systems, fluid-migration systems, and geotechnical hazard assessment (i.e., drilling and infrastructure). The HR3D survey (31.5 km (super 2) ) collected on the inner shelf (< 15 m water depth) offshore San Luis Pass, Texas, imaged the upper 500 m of stratigraphy using peak frequency of 150 Hz and 6.25 m (super 2) bin size. These data provided an exceptionally well-imaged example of shallow subsurface depositional system and stratigraphic architecture development during a lowstand period. The system evolved from a meandering channel with isolated point-bar deposits to a transgressive estuary characterized by dendritic erosional features that were eventually flooded. In addition, HR3D data have identified a previously unidentified seismically discontinuous zone interpreted to be a gas chimney system emanating from a tested (drilled) nonproductive, three-way structure in the lower Miocene (1.5 km depth). Within the shallowest intervals (< 100 m) and at the top of the chimney zone, seismic attribute analysis revealed several high-amplitude anomalies up to 0.5 km (super 2) . The anomalies were interpreted as reaccumulated thermogenic gas, and their distribution conforms to the stratigraphy and structure of the Quaternary interval, in that they occupy local fault-bounded footwall highs within remnant coarser-grained interfluvial zones, which are overlain by finer grained, transgressive deposits.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 4
Serial Issue: 1
Title: Use of novel high-resolution 3D marine seismic technology to evaluate Quaternary fluvial valley development and geologic controls on shallow gas distribution, inner shelf, Gulf of Mexico
Affiliation: University of Texas at Austin, Bureau of Economic Geology, Jackson School of Geosciences, Austin, TX, United States
Pages: SC35-SC49
Published: 201602
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 44
Accession Number: 2017-008934
Categories: OceanographyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map, 1 table, sect.
N28°52'60" - N33°04'00", W99°54'00" - W95°24'00"
Secondary Affiliation: Statoil, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201708
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