1 / 20

Chapter 7

Chapter 7. 3-D Seismic Exploration. Introduction. What is 3-D seismic? It is a group of closely spaced 2-D source and receiver lines forming a grid that covers an area. Receiver and source lines may be perpendicular or at an angle. Why 3-D seismic?

hazelton
Download Presentation

Chapter 7

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 7 3-D Seismic Exploration

  2. Introduction • What is 3-D seismic? • It is a group of closely spaced 2-D source and receiver lines forming a grid that covers an area. • Receiver and source lines may be perpendicular or at an angle. • Why 3-D seismic? • 3-D migration eliminates misties over dipping reflectors. • presents a more detailed image of the subsurface

  3. 3-D Terminology (Cordsen et al., 2000)

  4. 3-D Terminology (Cordsen et al., 2000)

  5. 3-D Terminology • Inline: direction parallel receiver lines. • Crossline: direction orthogonal receiver lines. • CMP bin: a small rectangle (1/2 RI x 1/2 SI) that contains all the traces which belong to the same CMP. • Box (unit cell): area bounded by two adjacent receiver lines and two adjacent source lines. • Patch (template): area of all live receivers recording from the same source. • Swath: length over which sources are recorded without crossline rollover.

  6. 3-D Swath Shooting Method • Receiver lines are laid in parallel lines. • Source lines are laid in parallel lines in a direction orthogonal to receiver lines. • An area of receivers (patch) is activated. • Source at patch center is shot and recorded. • Patch is moved crossline one source interval. • Source at new patch center is shot and recorded. • Repeat this until source line is finished. • This is one swath. • Roll over one source-line interval and begin recording the next swath. • Keep doing this until the survey is finished.

  7. 3-D Swath Shooting Method Crossline rollover Swath 1 Swath 2 SP # 6 SP # 5 SP # 4 SP # 3 SP # 2 SP # 1 Crossline rollover

  8. 3-D Land Survey Designs • Grid geometry • full fold • parallel • orthogonal • non-orthogonal • brick • Zigzag • Non-grid geometry • star • radial • random

  9. 3-D Land survey designsFull-fold (Cordsen et al., 2000)

  10. 3-D Land survey designsParallel (Cordsen et al., 2000)

  11. 3-D Land survey designsOrthogonal (Cordsen et al., 2000)

  12. 3-D Land survey designsNon-orthogonal (Cordsen et al., 2000)

  13. 3-D Land survey designsBrick (Cordsen et al., 2000)

  14. 3-D Land survey designsZigzag (Cordsen et al., 2000)

  15. 3-D Land survey designsStar (Cordsen et al., 2000)

  16. 3-D Land survey designsRadial (Cordsen et al., 2000)

  17. 3-D Land survey designsRandom (Cordsen et al., 2000)

  18. Factors Controlling 3-D Survey Design • Shallowest reflector of interest • Deepest reflector of interest • Target Size • Target dip • Multiples • Cost

  19. Parameters of 3-D Survey Design • RI and SI • RLI and SLI • CMP Fold • Maximum Offset • Minimum Offset • Record length • Frequency • Migration Aperture

  20. 3-D Marine Surveys • Shoot closely spaced parallel 2-D lines. • Cable may drift with water cross currents (feathering). • Correct for feathering effect using compasses along cable to determine source and receiver locations.

More Related