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Pitfalls in the seismic interpretation of fault shadow events; Vicksburg Formation of south Texas

Richard C. Bain
Pitfalls in the seismic interpretation of fault shadow events; Vicksburg Formation of south Texas (in Pitfalls in the structural interpretation of seismic data, Anonymous)
Interpretation (Tulsa) (February 2015) 3 (1): SB17-SB22

Abstract

Reliance on prestack time-migrated seismic data to define structural highs without incorporating all subsurface data and without taking into account the regional and local lateral depositional trends may result in dry holes or poorly positioned production wells due to local velocity changes, which are usually caused by some depositional or structural phenomenon. Tying check-shot control to depositional units may reveal those phenomena and permit assumptions to be made about velocities in areas beyond check-shot control points. We discovered a significant gas accumulation in an area surrounded by dry holes and marginal wells in the Vicksburg Formation in McAllen Ranch Field, Hidalgo County, Texas, by treating a seismic velocity anomaly as a geologic problem and by simple application of arithmetic and geometry to a 3D velocity model. Due to the effects of the anomaly, seismic data displayed in time gave no indication of the existence of a 325 ha (800 ac), 150 BCFG anticlinal structure. A subsurface model that accounted for the velocity anomaly was able to predict its extent and severity by readily identifiable thickness changes in the anomalous units. The resulting discovery yielded a sevenfold increase in field production within a two-year time span.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 3
Serial Issue: 1
Title: Pitfalls in the seismic interpretation of fault shadow events; Vicksburg Formation of south Texas
Title: Pitfalls in the structural interpretation of seismic data
Author(s): Bain, Richard C.
Author(s): Anonymous
Affiliation: Chevron USA, Houston, TX, United States
Pages: SB17-SB22
Published: 201502
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 6
Accession Number: 2015-034273
Categories: Economic geology, geology of energy sourcesApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: sects., strat. col., sketch maps
N26°10'00" - N26°40'00", W98°40'00" - W98°00'00"
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: 201516
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