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Pitfall experiences when interpreting complex structure with low-quality seismic images

Bob A. Hardage
Pitfall experiences when interpreting complex structure with low-quality seismic images (in Pitfalls in the structural interpretation of seismic data, William L. Abriel (prefacer), Alistair R. Brown (prefacer), Bob A. Hardage (prefacer), Donald A. Herron (prefacer), Robert A. Ratliff (prefacer) and R. Randy Ray (prefacer))
Interpretation (Tulsa) (February 2015) 3 (1): SB29-SB37

Abstract

Structural interpretation of seismic data presents numerous opportunities for encountering interpretational pitfalls, particularly when a seismic image does not have an appropriate signal-to-noise ratio (S/N), or when a subsurface structure is unexpectedly complex. When both conditions exist -- low S/N data and severe structural deformation -- interpretation pitfalls are almost guaranteed. We analyzed an interpretation done 20 years ago that had to deal with poor seismic data quality and extreme distortion of strata. The lessons learned still apply today. Two things helped the interpretation team develop a viable structural model of the prospect. First, existing industry-accepted formation tops assigned to regional wells were rejected and new log interpretations were done to detect evidence of repeated sections and overturned strata. Second, the frequency content of the 3D seismic data volume was restricted to only the first octave of its seismic spectrum to create better evidence of fault geometries. A logical and workable structural interpretation resulted when these two action steps were taken. To the knowledge of our interpretation team, neither of these approaches had been attempted in the area at the time of this work (early 1990s). We found two pitfalls that may be encountered by other interpreters. The first pitfall was the hazard of accepting long-standing, industry-accepted definitions of the positions of formation tops on well logs. This nonquestioning acceptance of certain log signatures as indications of targeted formation tops led to a serious misinterpretation in our study. The second pitfall was the prevailing passion by geophysicists to create seismic data volumes that have the widest possible frequency spectrum. This interpretation effort showed that the opposite strategy was better at this site and for our data conditions; i.e., it was better to filter seismic images so that they contained only the lowest octave of frequencies in the seismic spectrum.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 3
Serial Issue: 1
Title: Pitfall experiences when interpreting complex structure with low-quality seismic images
Title: Pitfalls in the structural interpretation of seismic data
Author(s): Hardage, Bob A.
Author(s): Abriel, William L.prefacer
Author(s): Brown, Alistair R.prefacer
Author(s): Hardage, Bob A.prefacer
Author(s): Herron, Donald A.prefacer
Author(s): Ratliff, Robert A.prefacer
Author(s): Ray, R. Randyprefacer
Affiliation: Bureau of Economic Geology, Austin, TX, United States
Affiliation: Chevron Global Upstream, San Ramon, CA, United States
Pages: SB29-SB37
Published: 201502
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 7
Accession Number: 2016-006933
Categories: Economic geology, geology of energy sourcesApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. chart, sects., sketch maps
Secondary Affiliation: Bureau of Economic Geology, USA, United States
Source Note: Online First
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: 201604
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