3D curvature analysis of seismic waveform & its interpretational implications

Transcription

1 INT E-P1: Attribute SEG D curvature analysis of seismic waveform & its interpretational implications Haibin Di, Motaz Alfarraj, and Ghassan AlRegib Center for Energy & Geo Processing (CeGP) Georgia Institute of Technology {hdi7, motaz, alregib}@ece.gatech.edu September 25, 2017

2 Outline Motivation Waveform curvature vs. geometric curvature Three implications Application to horizon modeling Conclusions 2

3 Motivation Curvature analysis is useful for measuring the reflector geometry to depict the surface morphology and highlight the potential faults and fractures caused by anticlinal bending (e.g., Roberts, 2001); The reflector geometry is only partial information offered in a seismic cube, and the reflection waveform is also of significant importance for interpreting the seismic signals; What if applying the curvature analysis to the reflection waveforms? 3

4 Curvature kk 2DD (x, z) = zz 1 + zz kk mmmmmm φφ 3DD xx, yy, zz = MAX(kk 3DD xx, yy, zz, φφ=[0o, 360 o )) kk mmiiii φφ 3DD xx, yy, zz = MIN(kk 3DD xx, yy, zz, φφ=[0o, 360 o )) where kk 3DD φφ xx, yy, zz = 1 1+AA 1 2 +AA BB 1 +BB 2 tan 2 φφ+2bb 3 tttttttt 1+AA AA 2 2 tttttt 2 φφ+2aa 1 AA 2 tttttttt 4

5 Waveform Curvature: 1D trace kk 2DD (z, w) = ww 1 + ww where z: vertical coordinate w: waveform amplitude 2 nd -order derivative resolution enhancement 5

6 Waveform Curvature: 2D section Crossline No. Take inline section for example: Sample No. kk mmmmmm φφ 3333 xx, zz, ww = MAX(kk 3333 kk mmmmmm φφ 3333 xx, zz, ww = MIN(kk 3333 xx, zz, ww, φφ=[0o, 360 o )) (in blue) xx, zz, ww, φφ=[0o, 360 o )) (in red) where x: crossline coordinate z: vertical coordinate w: waveform amplitude 6

7 Waveform Curvature Table: Geometric curvature vs. waveform curvature Object Information for analysis Computation direction Implications Geometric curvature Waveform curvature Curvature analysis of seismic signals a. Structural depth/time b. Reflection amplitude Reflection waveform Horizontal Vertical (the xx-yy plane) (the xx-zz and/or yy-zz plane) Structure analysis: Waveform analysis: a. Fault detection a. Resolution enhancement b. Fracture characterization b. Dip estimation c. Reflector morphology c. Reflector decomposition delineation 7

8 Implication #1: Resolution enhancement a. Curvature: 2 nd -order derivative better resolution b. Maximum curvature: Normal to the reflection more reliable analysis Original amplitude section Maximum waveform curvature 8

9 Implication #2: Dip estimation Minimum curvature: Parallel to the reflection reflector dip More in my next presentation at 3:05 pm Orientation of Minimum waveform curvature Dip-guided horizon tracking 9

10 Implication #3: Reflector decomposition Peaks Troughs S-crossings Z-crossings 10

11 Application to horizon modeling Seismic image Peak decomposition Thinning Horizon model Seeded horizon tracking Seed picking and sorting 11

12 Limitations Sensitivity to high-frequency components Sensitivity to vertical window size Sensitivity to seismic noises 12

13 Limitation #1: Sensitivity to high-frequency components Take Ricker wavelet for example ww tt = AA 1 2ππ 2 ff MM 2 tt 2 ee ππ2 ff MM 2 tt 2 Original amplitude Waveform curvature: kk 0, ww = 6 AA ππ 2 ff MM 2 Linear to amplitude A quadratic to frequency f Maximum waveform curvature

14 Limitation #2: Sensitivity to vertical window size Window size = 3 Window size = 5 Z Window size = 7 Window size = 9 Window size no larger than half of the waveform period

15 Limitation #3: Sensitivity to seismic noise From original seismic For resolution enhancement: use original amplitude For dip estimation : Apply smoothing first From smoothed seismic For horizon interpretation: Apply smoothing first

16 Conclusions Curvature analysis is extended to seismic waveforms; Several implications: Resolution enhancement along the direction normal to seismic reflectors Dip estimation Reflector decomposition to peaks, troughs, and z/s-crossings; Potentials for horizon interpretation and modelling 16

17 More information (e.g., recent research, publications, tools, and codes) is available by: Visit our booth: #2109 Visit our center: Visit my webpage: 17