Mapping and migrating reflected ground-roll

Transcription

1 Mapping and migrating reflected ground-roll Craig Hyslop Advisor: Dr. Stewart April 2, 2014

2 Outline 3D fault imaging Outline: Ground-roll reflection in-line Synthetics Field result 3D fault imaging off-line Synthetics 1

3 Outline 3D fault imaging Identify vertical-ish features Image lateral heterogeneity Determine velocity and statics Design better reject filters Discover near-surface anomalies 2

4 Outline 3D fault imaging Ground-roll (Rayleigh-wave) 3

5 Outline 3D fault imaging Ground-roll (Rayleigh-wave) 3

6 Outline 3D fault imaging Back-reflected ground-roll 4

7 Outline Back-reflected ground-roll 5 3D fault imaging

8 Outline 3D fault imaging Synthetic model and survey parameters Source Receiver Source interval Receiver interval 10 Hz Ricker vertical component 10 m 1 m 6

9 Outline 3D fault imaging For dispersive surface-waves Phase-velocity is a function of frequency. Extracted dispersion curve 7

10 Outline 3D fault imaging : Processing 8

11 Outline 3D fault imaging Reflectivity: Depth mapping 9

12 Outline 3D fault imaging Field Source Receiver Source interval Receiver interval vertical vib. vertical component processed 5 m 5 m 10

13 Outline 3D fault imaging Field result 11

14 Outline 3D fault imaging Field result 12

15 Outline 3D fault imaging Fault in-line vs. off-line 13

16 Outline Fault off-line 14 3D fault imaging

17 Outline Fault off-line 14 3D fault imaging

18 Outline Fault off-line 14 3D fault imaging

19 Outline Fault off-line 14 3D fault imaging

20 Outline Fault off-line 14 3D fault imaging

21 Outline Fault off-line 14 3D fault imaging

22 Outline Fault off-line 14 3D fault imaging

23 Outline Fault off-line 14 3D fault imaging

24 Outline Fault off-line 14 3D fault imaging

25 Outline Fault off-line 14 3D fault imaging

26 Outline 3D fault imaging Ground-roll migration One-way split-step phase-shift (Stoffa, 90) 2D X-Y (propagation in Y) Modified for dispersion Imaging condition - deconvolution 15

27 Outline 3D fault imaging Ground-roll migration 16

28 Outline 3D fault imaging Ground-roll migration 16

29 Outline 3D fault imaging Ground-roll migration 16

30 Outline 3D fault imaging Ground-roll migration 16

31 Outline 3D fault imaging Ground-roll migration 16

32 Outline 3D fault imaging Ground-roll migration 16

33 Outline 3D fault imaging Ground-roll migration 17

34 Outline 3D fault imaging Ground-roll migration: 2 18

35 Outline Ground-roll migration: D fault imaging

36 Outline Ground-roll migration: D fault imaging

37 Outline Ground-roll migration: D fault imaging

38 Outline Ground-roll migration: D fault imaging

39 Outline Ground-roll migration: D fault imaging

40 Outline Ground-roll migration: D fault imaging

41 Outline Ground-roll migration: D fault imaging

42 Outline Ground-roll migration: D fault imaging

43 Outline Ground-roll migration: D fault imaging

44 Outline Ground-roll migration: D fault imaging

45 Outline Ground-roll migration: D fault imaging

46 Outline Ground-roll migration: D fault imaging

47 Outline Ground-roll migration: D fault imaging

48 Outline Ground-roll migration: D fault imaging

49 Outline Ground-roll migration: D fault imaging

50 Outline 3D fault imaging Depth imaging 20

51 Outline 3D fault imaging Near-surface is important to define. Identifying faults. Determining statics. Designing filters. Useful information in back-reflected ground-roll. Defines sharp lateral heterogeneity. Frequency content adds depth dimension. Deconvolution is effective in imaging faults from ground-roll. 21

52 Outline 3D fault imaging Thank you 22

53 Outline 3D fault imaging Frequency-to-depth: Mapping Surface waves are most sensitive to the velocity structure at one-half the wavelength of the surface wave (Rix et. al., 1989). Likewise, surface waves are also most sensitive to reflectivity of the structure at one-half the wavelength. 23