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Application of thin-bed indicator and sweetness attribute in the evaluation of sediment composition and depositional geometry in coast-perpendicular subbasins, south Texas Gulf Coast

Osareni C. Ogiesoba
Application of thin-bed indicator and sweetness attribute in the evaluation of sediment composition and depositional geometry in coast-perpendicular subbasins, south Texas Gulf Coast
Interpretation (Tulsa) (February 2017) 5 (1): T87-T105

Abstract

My focus of study is the nature of sediments within late Eocene to middle Oligocene, coast-perpendicular subbasins located on the southwest side of the San Marcos Arch in Refugio County, near the South Texas Gulf Coast. Methods of investigation consist of 3D seismic interpretation, seismic attribute, and isochron mapping. Depositional geometry, inferred sediment composition, and bed-thickness data are examined by extraction of amplitude-envelope, sweetness, and thin-bed-indicator (TBI) attributes from the 3D seismic volume. Four subbasins, numbered SB1 through SB4 from northeast to southwest, are recognized. Although the coast-perpendicular subbasins formed at the same time and by the same processes, the sediment distribution, basin-fill history, and tectonics differ from subbasin to subbasin within the Jackson, Vicksburg, and Frio Formations. Amplitude envelopes extracted at base Jackson and at near-base Vicksburg Formation show that, although the distribution pattern of interpreted sandstone-prone sediments within each subbasin is mainly of sheet geometry, SB2 displays a pattern of short, narrow, linear features. Based on available well control, the sweetness and TBI attributes correlate well with V (sub clay log) . Crossplots between V (sub clay) and sweetness exhibit a strong, linear, negative relationship--the sweetness value increases as the V (sub clay) value decreases, suggesting an increasing sandstone content. In contrast, crossplots between V (sub clay) and TBI exhibit a positive linear relationship--the TBI value increases as the V (sub clay) value increases, suggesting an increasing shale content. Because the sweetness attribute may in some cases not detect some thin shale bed within a stratigraphic interval, it may overestimate the net:gross ratio. Therefore, a combined TBI and sweetness procedure is required to determine the net:gross ratio. The results show that the net:gross ratio decreases from SB1 closest to the San Marcos Arch, to SB4 farthest into the Rio Grande Embayment. The approach adopted in this study can be used to estimate net:gross ratios in frontier areas.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 5
Serial Issue: 1
Title: Application of thin-bed indicator and sweetness attribute in the evaluation of sediment composition and depositional geometry in coast-perpendicular subbasins, south Texas Gulf Coast
Affiliation: Bureau of Economic Geology, Austin, TX, United States
Pages: T87-T105
Published: 201702
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 19
Accession Number: 2017-006000
Categories: Economic geology, geology of energy sourcesApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., strat. col., sketch maps
N28°04'60" - N28°30'00", W97°30'00" - W96°45'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201705
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