DoodleTrain

Seismic Data Acquisition, Processing and Inversion in Exploration Seismology

Instructor: Öz Yilmaz 
Date: November 08 - 09, 2018
Duration: 2 days
Members (early bird/price): CAD$ 800/1000 (plus GST)
Non-members (early bird/price): CAD$ 900/1100 (plus GST)
Location: TBA
Time: TBA

Course Description

 Day 1:

1a. The meaning of the near-surface in earthquake seismology, exploration seismology, and engineering seismology; two deleterious effects of the near-surface in exploration seismology: (1) the near-surface causes distortions of subsurface reflection traveltimes and amplitudes, and (2) the near-surface gives rise to surface waves which can severely mask subsurface reflections on recorded data;

1b. Seismic wave propagation in the near-surface: particle motion induced by body waves, seismic wave velocities in the near-surface, particle motion induced by surface waves;

1c. Rayleigh-wave amplitudes: model experiments and field experiments;

1d. Dispersion spectrum of Rayleigh waves;

1e. Factors that influence surface-wave propagation in the near-surface --- source depth, velocity contrast between the near-surface and the subsurface, thickness of the near-surface, near-surface geometry, near-surface velocities, near-surface heterogeneities, wave attenuation in the near-surface, surface topography, and recording geometry;

2a. Traveltime inversion applied to first-arrival times to estimate the P-wave velocity-depth model for the near-surface: model experiments and field experiments;

2b. Rayleigh-wave inversion to estimate the S-wave velocity-depth model for the near-surface: model experiments and field experiments;

2c. Borehole velocity measurements: borehole seismic data acquisition, borehole seismic data analysis, comparison of surface-seismic and borehole-seismic velocity estimates, P-S suspension logging;

2d. What geophone component (X, Y, Z) combined with what source orientation ((X, Y, Z) are required to record optimally reflected PP, SS, SP, and PS modes, Rayleigh waves, and Love waves, and what is the effect of the near-surface on the reflected wave modes;

3a. Model experiments: a near-surface model with irregular topography and several layers with arbitrary geometry for traveltime inversion to estimate the near-surface model for statics corrections --- defining floating datum and intermediate datum shot interval for first-arrival picking defining the initial model;

3b. Model experiments: a near-surface model with irregular topography and several layers with arbitrary geometry for image-based i-stats method to estimate the near-surface model for statics corrections --- building an effective-medium model for the near-surface without picking first breaks;

3c. Model experiments: a near-surface model with irregular topography and several layers with arbitrary geometry for wavefield inversion (FWI) to estimate the near-surface model for statics corrections;

4. Model experiments: a near-surface model with irregular topography and vertical velocity gradient associated with sand dunes for traveltime inversion and the image-based istats methods to estimate the near-surface model for statics corrections;

Day 2:

5a. Case study 1: sand dunes for traveltime inversion to estimate the near-surface model for statics corrections;

5b. Case study 1: sand dunes for the i-stats method to estimate the near-surface model for statics corrections;

5c. Case study 2: solution collapses associated with anhydrite layer for traveltime inversion to estimate the near-surface model for statics corrections;

5d. Case study 2: solution collapses associated with anhydrite layer for the i-stats method to estimate the near-surface model for statics corrections;

5e. Case study 3: glacial till for traveltime inversion to estimate the near-surface model for statics corrections;

5f. Case study 3: glacial till for the i-stats method to estimate the near-surface model for statics corrections;

5g. Case study 4: salt-filled karstic formation for traveltime inversion to estimate the near-surface model for statics corrections;

5h. Case study 4: salt-filled karstic formation for the i-stats method to estimate the near-surface model for statics corrections;

6a. Case study for 3-D traveltime inversion to estimate the near-surface model for statics corrections;

6b. First-break picking of 3-D data and the problem of source-receiver azimuthal variations in statics corrections;

7a. Large-offset recording case studies: capturing wide-angle reflections; swath-line recording case studies: in areas with rough topography with difficult accessibility;

7b. Spatial sampling requirements for optimum shot and receiver intervals;

8. Review of migration strategies: time vs. depth migration 2-D vs. 3-D migration poststack vs. prestack migration;

9. Image-based estimation of rms velocity field for prestack time migration and construction of velocity-depth model for prestack depth migration;

10. Case study 1 for imaging in areas with irregular topography, complex near-surface, and complex subsurface;

11. Case study 2 for imaging in areas with irregular topography, complex near surface, and complex subsurface --- the problem of velocity uncertainty;

12a. Zero-offset migration vs. prestack migration: back to the future --- return of the DMO;

12b. Preparing for the i-cube workflow for subsurface imaging: properties of stack cube, migration cube, and demigration cube --- model experiments with conflicting dips and point diffractor;

12c. Case study for the i-cube workflow for subsurfaced imaging; and

12d. Combining the i-cube workflow with structurally consistent rms velocity updating.

Biography

Öz Yilmaz received his B.S. in Geology with Geophysics Option from the University of Missouri-Rolla in 1970, M.S. in Geophysics with research in rock physics and earthquake seismology from Stanford University in 1972, and after five years in the industry, and Ph.D. in Geophysics with research in exploration seismology from Stanford University in 1979.  Aside from numerous publications on all aspects of seismic data analysis, Öz wrote a book entitled Seismic Data Processing published by SEG in 1987.  The expanded, two-volume second edition entitled Seismic Data Analysis was published, again by SEG, in January, 2001.  And his third book is entitled Engineering Seismology published by SEG, May, 2015.  Öz Yilmaz is the Director of Anatolian Geophysical, which provides services in exploration seismology, engineering seismology, and earthquake seismology.  Öz Yilmaz also is the CTO of GeoTomo LLC, which provides seismic software products and services in near-surface and subsurface modeling and imaging.