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Structural Styles

Structural Styles

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Structural Styles

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  1. Structural Styles Brenton, David, & Ryan

  2. Shear fold formed as fault tip displacement was lost near the surface Normal-fault related structures Syncline formed by growth faulting

  3. Nigeria profile Normal-fault related structures Cretaceous strata onlap Syncline formed by growth faulting Jurassic faulting

  4. Fault arrays under the Browse Basin NW continental margin of Australia Mostly normal throws - partial inversion on the NW side of section? Post breakup unconformity overlain by strata that onlap significant relief across the section

  5. Normal-faulted clinoforms, offshore Namibia

  6. Thrust-Related Structures: Buckle folded Messinian strata, Western Ionian

  7. Imbricate Thrust System:Glacial thrust belt, Danish North Sea

  8. Toe of the Delta Thrust Faults, Deep Water Niger Delta Connors, 2009

  9. Connors, 2009 Virtual Seismic Atlas

  10. Virtual Seismic Atlas

  11. Flower Structures Positive Flower Negative Flower

  12. Fault Imaging Challenges • Juxtaposition of different velocity rocks causes issues with seismic profiles. • Ex: Thrust faults-faster velocity rocks over slower rocks • Salt Intrusions • Planar faults appear curved • velocity increases with depth • constant thickness of rocks represented by smaller TWT at depth than shallower

  13. Case Study: LLanos Foothills, Columbia Located between Eastern Cordillera and the undeformed foreland basin Exploration in the mid 90's led to the discovery of 2 major fields: Cusiana and Cupiagua BPXC - 2000km 2D sesimic - 800km23D Estrada & Jaramillo (2003)

  14. Case Study: LLanos Foothills, Columbia Modeling showed long tails generated by overturned thrust sheets Post stack migration caused reflectors beneath the thrust sheets to be broken up Estrada & Jaramillo (2003)

  15. Reprocessing Estrada & Jaramillo (2003)

  16. Estrada & Jaramillo (2003)

  17. Wasn't possible to define the limits of the Cupiagua field 3D acquisition resulted in "step-change" in data quality 3D seismic Quality of 2D lines was seen as adequate for the appraisal of the Cusiana. Estrada & Jaramillo (2003)

  18. Seismic Attributes • An attribute is a measured characteristic taken from seismic data • Can reveal features that could easily be missed and aid in interpretation • Especially important in imaging complex fault systems • For faults the two most important attributes are coherency and volumetric curvature

  19. Coherency • The measure of similarity between traces in a small analysis window Nissen, 2007

  20. Bahorich, 1995

  21. Coherency Cube Virtual Seismic Atlas

  22. References Bahorich, Mike, and Steve Farmer. "3-D Seismic Discontinuity for Faults and Stratigraphic Features: The Coherence Cube: ABSTRACT." The Leading Edge (1995): 1053-058. Connors, C. D., B. Radovich, A. Danforth, and S. Venkatraman. "The Structure of the Offshore Niger Delta." Orsget (2009): 182-88. Estrada, C. A., & Jaramillo, J. A. (2003). Making the difference: A story of pitfalls and successes in seismic imaging in a thrust belt environment. Nissen, Susan. Using 3-D Seismic Attributes in Reservoir Charaterization. 9 Aug. 2007. Presentation. Hays, KS. Virtual Seismic Atlas, http://see-atlas.leeds.ac.uk:8080/home.jsp