I gave this class part of the Geophysical Society of Houston annual Geophysics Academy.

Advanced Depth Imaging Agenda

Alexander Mihai Popovici, CEO, Z-Terra Inc.

Velocity Model Building

Main concepts and the evolution over time of migration velocity analysis (MVA) and tomography.

Automatic PSTM velocity model computation methods .

1. Beam Forming for automatic Vrms generation.
2. AutoImager by Data Modeling Inc.
3. Kinematic Invariant Velocity Update (KIVU).

PSDM velocity model, tomography and evolving the velocity model from time to depth.

1. Migration Velocity Analysis (MVA) and fundamentals of updating the velocity model and iterative MVA.
2. Wave-equation MVA and angle gathers.
3. Reflection Tomography.  Horizon based tomography.  Grid based tomography.
   1. Single value tomography.
   2. Multiple value tomography (MVT).
   3. Azimuth sectors and MVT.
   4. Extended Gathers.
   5. Beam Tomography.
4. Full Waveform Inversion (FWI).
5. Beam Tomography as a faster and more stable alternative to FWI.

Effect of rugosities on top structures for imaging complex structures.  Illumination effects.

Building velocity models with complex salt bodies.

Imaging Methods

Prestack depth migration and prestack time migration fundamentals.

Wave-equation depth migration improvements, theory, image comparisons.

• Kirchhoff.
• Common Azimuth migration, Shot Profile migration.
• Reverse Time Migration.
• Gaussian Beam Migration, Fast Beam Migration.
• 5-D and 6-D Data Regularization.
• Wave Equation Multiples Imaging.

Fast Beam Migration.  Beam Forming by Slant Stack.  Beam Forming by Plane Wave Destructor (PWD) filters.  Image Forming by Beam Migration and Reconstruction.

Short Review of Beam Forming and Beam Migration:

1. Data Decomposition via Beam Forming.
2. Migration and Image Reconstruction.
3. Fast Beam Migration implementation and examples.
4. Gaussian Beam Migration implementation and examples.

Results, synthetic, real data.

Anisotropy effects in depth migration.  Imaging in the presence of anisotropy and evaluating the anisotropy.

Broadband Diffraction Imaging

Diffraction Imaging (DI) is a high-resolution imaging technology designed to image and identify in very fine detail the small scale fractures in shale and carbonate reservoirs that form areas of increased natural fracture density.  Diffraction Imaging provides a separate 3D (stack), 4D (angle gathers) or 5D (angle and azimuth gathers) image of discontinuities, or objects which are small compared to the wavelength of seismic waves such as fault edges, small scale faults, fractured zones, pinch-outs, reef edges, channel edges, salt flanks, reflector unconformities, injectites, fluid fronts, caves and karst, in general any small scattering objects. 

Overview of Diffraction Imaging (DI)

1. Diffraction and scattering theory.
2. Specular reflections vs. diffractions.
3. Diffraction imaging benefits; super-resolution.
4. DI implementation in Kirchhoff time and depth migration.
5. Pre-processing pitfalls in removing diffractions.

Diffraction imaging examples and comparisons.

1. Synthetic examples.
2. Real data examples. 
3. Amplitude with azimuth. 
   1. Direction of stress fields.
   1. Visualize azimuthal dependence.
4. Correlation of diffraction imaging attributes with production.