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Compaction-induced anisotropy and time-lapse AVO analysis

Nayyer Islam and Wayne D. Pennington
Compaction-induced anisotropy and time-lapse AVO analysis (in Monitoring reservoir and overburden changes, David Johnston (prefacer), David Monk (prefacer), Baishali Roy (prefacer), Tim Barker (prefacer), Ivar Sando (prefacer), Mike Helgerud (prefacer), Lydia Novakovic (prefacer) and Mike Fry (prefacer))
Interpretation (Tulsa) (May 2015) 3 (2): SP21-SP33


Hydrocarbon reservoirs are often monitored using repeated seismic observations to track fluid movement and other changes. Here, we present a study of compaction-induced anisotropy in an unconsolidated overpressured sandstone reservoir from Teal South field in the Gulf of Mexico. Previous work at Teal South had demonstrated that the time-lapse observations could not be satisfied through models of fluid changes without strong pressure effects acting on the formation rock framework. However, those studies are not highly quantitative, and some minor inconsistencies appear on closer examination. We have examined the effect of the pressure-sensitivity of elastic moduli in the formation and carefully examined the offset-dependence of amplitudes in light of several rock-physics models, empirical and theoretical. The amplitude-variation-with-offset behavior for the interface between overlying shale and the hydrocarbon sand is best modeled under the assumption that this overpressured reservoir becomes anisotropic because it undergoes compaction during production, which reduces the reservoir pressure from highly overpressured to nearly normal for this depth. Although the results obtained here are only weakly constrained due to the limited offset ranges and low fold, this strongly suggests that anisotropic effects in poorly consolidated overpressured reservoirs undergoing primary depletion may in fact dominate over fluid effects after the bubble point has been reached.

ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 3
Serial Issue: 2
Title: Compaction-induced anisotropy and time-lapse AVO analysis
Title: Monitoring reservoir and overburden changes
Author(s): Islam, NayyerPennington, Wayne D.
Author(s): Johnston, Davidprefacer
Author(s): Monk, Davidprefacer
Author(s): Roy, Baishaliprefacer
Author(s): Barker, Timprefacer
Author(s): Sando, Ivarprefacer
Author(s): Helgerud, Mikeprefacer
Author(s): Novakovic, Lydiaprefacer
Author(s): Fry, Mikeprefacer
Affiliation: Michigan Technological University, Houghton, MI, United States
Affiliation: ExxonMobil, Houston, TX, United States
Pages: SP21-SP33
Published: 201505
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 36
Accession Number: 2015-073936
Categories: Economic geology, geology of energy sourcesApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. 3 tables
N18°00'00" - N30°04'00", W98°00'00" - W80°30'00"
Secondary Affiliation: Apache, USA, United StatesConocoPhillips, USA, United StatesShell, USA, United StatesStatoil, NOR, NorwayChevron, USA, United StatesBP, USA, United States
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: 201532
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