2. Measuring, imaging and suppressing scattered surface waves Xander Campman*, Kasper van Wijk, John Scales and Gérard Herman** * Dept. of Applied Mathematics Delft University ** Shell Int. E & P and Delft University

3. Near-receiver scattering

4. Vs=400 m/s, Vp=1700 m/s Vs=600 m/s, Vp=2500 m/s h d w Example w  d < h <<

5. Vertical velocity

6. Aligned at first breaks

7. Stacked

8. Scattered noise model

9. Outline of the scheme 1. Estimate velocity of the scattered surface wave  u G 2Estimate near-surface scattered energy from one isolated event. 3 Image the scattered energy  impedance distribution,  4 Predict and remove scattered surface waves on the entire record

10. Validation experiment A B

11. Seismic record, inline Direct Rayleigh wave Sound wave Ghost Rayleigh wave Scattered Rayleigh wave Cavity AB

12. Step 1: Estimate surface wave velocity c ~ 3000 m/s AB

13. Step 2: Separate scattered energy Direct Rayleigh wave : d Scattered energy : d 1 ABAB

14. Step 3: Estimate impedance function Impedance function:  cross-section at t=0 for entire data volume A B AB

15. Scattered noise model

16. Step 4: Predict scattered energy Ghost Rayleigh wavePredicted scattered field AB AB

17. Step 4: Subtract predicted scattered energy -= AB AB AB Ghost minus scattered

18. Transmission experiment Top view Side view AB

19. Transmission data AB

20. Step 1: Separate scattered energy First arrival : dScattered energy : d 1 AB AB

21. Step 2: Estimate impedance distribution Impedance function cross-section at t=0 for entire data volume AB AB

22. Step 4: Predict scattered field on the rest of the record AB

23. Input data after dip-filtering AB

24. Output data AB Rest minus scattered

25. Latest experiment

27. Acknowledgments Dutch Technology Foundation (STW) for financial support. Army Research Office and NSF also for financial support Everyone at PAL and CWP Shell Int. E&P and Wim Mulder (SIEP) for the use of FD code Jan Willem van den Dries for the artist impression