1 / 19

Seismic Ray Paths Exploration: Understanding Wave Behavior in Geophysics

Engage in laboratory exercises exploring seismic wave behaviors through reflection, refraction, and direct wave analysis. Gain insights from interpreting data for gravity, resistivity, GPR, and well logs.

jbunnell
Télécharger la présentation

Seismic Ray Paths Exploration: Understanding Wave Behavior in Geophysics

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. Exploration and Environmental Geophysics Ray Paths Exercise Jeffrey A. Nunn Louisiana State University

  2. Gravity Acquisition Gravity/Magnetics Interpretation Ray Paths Refraction Acquisition Landmark/Refraction Interpretation Reflection Acquisition Reflection Processing Reflection Interpretation Resistivity Survey Resistivity Interpretation Well Logs (BakerHughes) GPR Acquisition GPR Interpretation Laboratory Exercises

  3. Context • Audience: • Graduate/Undergraduate; Some PE students • 20 Students • Weekly Laboratory • Skills • Reflection • Refraction • Direct Wave • Ground Roll

  4. Grotzinger et al., 2006

  5. Ray Paths Burger, 1992

  6. Air Ground Roll Reflection Head Direct

  7. Goals • Students gain a strong visual image of how different waves travel different paths at different speeds which causes them to arrive at a geophone at different times. • Interpret arrival data in terms of refraction, reflection, direct wave, and ground roll.

  8. Instructions • For the next two exercises, we will break up into groups of four. • Each member of the group will represent one of four waves leaving the source: direct wave, ground roll, reflected wave, and head wave. • All four "waves" will leave the source at the same time and travel at a particular speed and path as directed by the instructor. • ALL students will record the arrival time of each "wave" at each geophone until all 12 geophones have been used.

  9. Students As Seismic Waves

  10. http://www.pi.ac.ae/pge/gallery/geophysics_trip_Mar07.htm Laying Out Seismic Cable http://www.seismo.unr.edu/ftp/pub/louie/class/453/album00/reflection.jpg

  11. Distance Versus Time for Various Students

  12. Ground Roll Reflection Head Direct

  13. Direct

  14. Head

  15. Reflection

  16. Things I Learned the Hard Way(Everybody has to “March” at the same cadence)

  17. Ground Roll Reflection Head Direct

  18. Head Direct

  19. Laboratory Report • For each geophone, list the order in which the four waves arrive. In addition, sketch the ray paths from the source to geophones 4, 8 and 12 • Plot arrival time versus distance for each "wave". Do any of the time versus distance curves fit a straight line? Do any of them not fit a straight line? Explain why they do or don't fit a straight line. • How would the arrival time versus distance curves be different if the distance to the horizontal/parallel surface was greater? How would the arrival time versus distance curves be different if the velocity of the "waves" in the upper medium was slower? • Without any additional information, is it possible to determine that the subsurface layer is dipping? If so, how?

More Related