Seismic Reflection 4: Acquisiton, Processing, and Waveform Analysis

1. Introduction to Geophysics Ali Oncel [email_address] Department of Earth Sciences KFUPM Seismic Reflection 4: Acquisiton, Processing, and Waveform Analysis Introduction to Geophysics-KFUPM

2. Types of Velocities Average Velocity Root mean Square Velocity (RMS) Interval velocity Previous Lecture Introduction to Geophysics-KFUPM

3. Example: Disk Formula v 1 =1500 m s -1 v 2 =2000 m s -1 v 3 =2345 m s -1 t 1 =2.14 s t 2 =1.21 s t 3 =1.13 s What is v rms at the base of layer 3? Introduction to Geophysics-KFUPM

4. Introduction to Geophysics-KFUPM

5. Introduction to Geophysics-KFUPM Fig 5.21 of Lillie

6. Introduction to Geophysics-KFUPM

7. “ 12 elephants dancing in unison” (LITHOPROBE, CANADA) A vibrator truck Vibroseis images from the Lithoprobe Project, Canada www.lithoprobe.ca Introduction to Geophysics-KFUPM

8. Introduction to Geophysics-KFUPM Fig. 5.23 of Lillie

11. Example: Air-water reflection ρ air =0; Vp=330 m/s ρ water =1; Vp=1500m/s R AirWater = (I Water -I Air ) / (I Air +I Water ) R AirWater = (I Water -0) / (0+I Water ) R AirWater = 1 Introduction to Geophysics-KFUPM Air Layer 1 Layer 2

12. ρ air =0; Vp=330 m/s ρ water =1; Vp=1500m/s Example: Water-air reflection R WaterAir = (I Air -I Water ) / (I Air +I Water ) R WaterAir = -1 ( A negative reflection coefficient) Introduction to Geophysics-KFUPM Air Water Layer 1 Layer 2

13. Introduction to Geophysics-KFUPM

15. Introduction to Geophysics-KFUPM b) Seismic response for reflection at interface with positive reflection coefficient c) Seismic response for negative reflection coefficient Fig. 5.26 of Lillie a) Input minimum phase and zero phase seismic signals

16. Introduction to Geophysics-KFUPM High Frequency Input

17. Introduction to Geophysics-KFUPM Low Frequency Input

18. Introduction to Geophysics-KFUPM

19. Introduction to Geophysics-KFUPM