Geophysics - Surface Imaging

Migration, Velocity Model Building and Updating



  Mr Piet Gerritsma (Gerritsma Geophysical Training and Consultancy, Netherlands)


  2 days


  Geophysics – Surface Imaging






  10 CPD points




Course description

The process of migration, whereby a proper image in time or depth of the subsurface is obtained, is directly related with the velocity model that both serves as input for the migration process as well as is the result of such a migration. Therefore migration and velocity model building are intimately related processes. The implementation of migration is characterized by a multitude of methods and algorithms; there is also a great variety of methods to build a velocity model. This course provides an overview of the migration principles, methods and algorithms and an overview of velocity model building principles and methods and algorithms. Examples and case studies will conclude this course.


Course objectives

At the end of the course the participants will have obtained a complete overview and thorough understanding of the many alternative methods and algorithms that are currently in use in imaging and velocity model building.
The course emphasizes for each method the underlying geophysical model together with its assumptions and strengths and weaknesses; many examples will be shown to illustrate the material; theory with references will be included; a handout that covers all course material will be made available.


Course outline

The following steps in Migration, DMO and Velocity Model Building will be discussed:

1. Migration or imaging

  • Migration, modelling and inversion
  • Geometric approach to migration
  • Examples
  • Resolution before and after migration
  • Aliasing
  • Ray definitions
  • The Dix equations
  • Definition of time migration and depth migration
  • The acoustic wave equation
  • Factorization of the wave equation
  • Forward and inverse wavefield extrapolation in depth
  • Migration principles; the imaging conditions
  • Migration of various data sets:
    • Shot profile migration
    • Survey sinking or redatuming
    • Zero-offset data migration
  • Extended imaging conditions (time-shift and/or space-shift)
  • Migration algorithms:
    • (k,f)-migration (Stolt)
    • Phase-shift migration (Gazdag)
    • Phase-shift-plus-interpolation (PSPI) migration
    • Split-step-Fourier (SSF) migration
    • Extended split-step Fourier (ESSF) migration
  • The Kirchhoff integral, the Rayleigh integral and Green’s functions
  • Kirchhoff (= summation or diffraction stack) migration
  • Migration by double focused array synthesis
  • Gaussian beam migration
  • Reverse time migration — RTM
  • Migration and demigration

2. Velocity model building

  • Minimal data sets and common image gathers — CIG’s
  • Iterative velocity model building with CIG’s
  • The migration conditions
  • Migration and traveltime inversion
  • Migration and demigration
  • Normal incidence wavefront curvature and stacking velocity
  • Velocity model parameterization
  • Velocity model building methods:
    • coherency inversion or model based stack
    • map migration
    • dynamic map migration (DMM) or curvature inversion
    • stereotomography
    • traveltime inversion (TTI)
    • traveltime inversion in the migrated domain (TIMD)
    • common focus panel (CFP) analysis
    • tomographic velocity model building
    • depth focusing analysis (DFA)
    • WEMVA: wave-equation migration velocity analysis
    • differential semblance optimization (DSO)
    • full waveform inversion (FWI)

4. Case studies — Examples

  • Tomography
  • Full Wave Inversion
  • Velocity Model Building
  • Parametric Velocity Estimation


Participants' profile

ocessing and interpretation ` geologists and petrophysicists who wish to understand how the various types of velocity information can be derived from seismic data and who wish to understand how subsurface images are generated.

As the material covers the theory and practical implementations of present day practices, this course is relevant for those who are fresh from university as well as for those who wish to be updated on the newest developments. Participants should have a basic understanding of seismic acquisition and processing practices.



Course participants should have a basic understanding of seismic acquisition and processing practices.


About the instructor

Piet GerritsmaPiet Gerritsma (1942) graduated in physics at the University of Groningen. He joined Shell in 1969 as a research geophysicist in Rijswijk (The Netherlands) and Houston (USA). He was actively involved in the development of programs for statics, velocity analysis, synthetic seismograms and raytracing, deconvolution, multi-component seismic, shear waves and anisotropy, AVO and migration. He acquired operational experience as processing and special studies geophysicist in Brunei and in Canada. He was Shell"s representative in international research consortia: SEP (Stanford), DELPHI (Delft University of Technology) and IFP (Institut Francais du Petrole); he also served as associate editor of Geophysical Prospecting on Migration, Modelling and Inversion. During his Shell career he has always lectured at both basic as well as advanced level covering a broad range of topics. He left Shell in 1999 after 30 years of service. Since that time he is a lecturer at CTG (Center for Technical Geoscience) at the Delft University of Technology. He also teaches regularly courses for national and international oil companies and service companies, both as an independent teacher as well as on behalf of geoscience training alliances. He has presented this course several times on behalf of the EAGE and CSEG.


                    Learning Geoscience Logo


Explore other courses under this discipline:


Full Waveform Inversion in an Anisotropic World. Where Are the Parameters Hiding?

Instructor: Prof. Tariq Alkhalifah (KAUST)

The course starts by introducing the fundamentals of full-waveform inversion (FWI) starting from its basic definition. It focuses on the model update issues and provides analysis of its probable success in converging to a plausible model. In the course we will discuss the many challenges we face in applying FWI on seismic data and introduce modern day proposed solutions to these challenges. The focus of the course will be on FWI applied to anisotropic media. As a result, the course will also introduce anisotropy, its optimal parametrization and wavefield simulation in such media. Practical multi-parameter inversion for anisotropic parameters requires an optimal FWI setup. We will discuss such a setup, which includes the proper parametrization of the medium and data access scheme necessary for a potential convergence to a plausible anisotropic model.

More information

Principles and Applications of Seismic Interferometry and Ambient Noise Seismology in Hydrocarbon Exploration

Instructor: Dr Gerard Schuster (KAUST)

This one-day course is designed for a broad range of seismic researchers, data processors, and interpreters working in the petroleum industry. The course teaches the principles of seismic interferometry, ambient noise seismology and their applications to surface seismic, VSP, and OBS data. The ultimate objectives are to enable geophysicists to evaluate the potential of seismic interferometry in uniquely solving their problems.

More information

Seismic Diffraction – Modelling, Imaging and Applications

Instructors: Prof. Evgeny Landa (Tel Aviv University) and Dr Tijmen Jan Moser (Moser Geophysical Services)

Diffractions have been identified as the key seismic manifestation of fractures and other small-scale reservoir heterogeneities. This two-day course will present the current state-of-the-art of diffraction technology and put this in context by a review of its past developments. The course will cover both forward diffraction modeling and diffraction imaging. Case studies of diffraction imaging will be presented covering applications in seismic exploration and other areas of geoscientific interest.

More information

3D Tomography by Active and Passive Seismic Data

Instructor: Prof. Dr Aldo Vesnaver (The Petroleum Institute)

Building a 3D Earth model in depth is needed not only for accurate seismic imaging, but also for linking well data (as logs and cores) and reservoir simulations. Tomography can build a 3D macro-model for P and S velocities that integrates surface and well data, as well as active and passive seismic. This short course will introduce the basic concepts of traveltime inversion keeping all the math at a very basic level.

More information

Applied Depth Imaging

Instructor: Dr Ruben Martinez (Reservoir Geoscience)

This course has two main segments. In the first segment, the participant will understand the basic concepts behind the tools commonly employed in velocity model building and depth migration.
In the second segment, the participant will learn how to use these tools for building velocity models and generate seismic images in depth using practical work flows for a variety of complex geologic scenarios. At the end of the course, an overview of the emerging depth imaging technologies is presented.

More information

Beyond Conventional Seismic Imaging

Instructor: Prof. Evgeny Landa (Tel Aviv University)

While depth imaging play an increasing role in seismic exploration, data analysis and imaging in time domain play an important role. Moreover, for complex models that request the use of prestack depth migration, time imaging usually constitutes a key first step. The proposed course discusses: a) data analysis and imaging based on new procedures such as Multifocusing and Common Reflection Surface; b) diffraction Imaging based on diffracted energy targeting to image small scale subsurface objects; c) imaging without precise knowledge of the subsurface velocity model (path summation); d) pitfalls and challenges of seismic inversion.

More information

Image Log Interpretation

Instructor: Prof. Peter Lloyd (Honorary Professor)

The course has been designed for geoscientists, engineers and other technical staff who want to analyze and integrate image and dip data with other logs and seismic to enhance their understanding of exploration plays and field development. It leans heavily on worked class examples and case studies. Instead of interpreting image and dip data in isolation, the course shows how they can be used in conjunction with cores, other logs, modern depositional analogues, outcrop studies and hi-resolution seismic data to refine reservoir models.

More information

Seismic Depth Imaging and Anisotropic Velocity Model Building

Instructor: Mr Etienne Robein (ERT)

The course will present in simple terms (cartoons rather than equations!) the principle of different techniques in each class of methods (Kirchhoff, Beam Migrations, WEM, RTM), while pointing out their respective merits and limitations. Similarities and differences between Time- and Depth-Imaging will be briefly reminded. In parallel, special emphasis is put on methods used to build the necessary anisotropic velocity models. Both Ray-based techniques (linear and non-linear tomography) and wavefield extrapolation-based ones, including Full Waveform Inversion, are addressed.

More information

Full-Waveform Inversion for High-Resolution Reservoir Characterization

Instructor: Prof. Dr Dries Gisolf (Delft Inversion)

This two-day course will start with an introduction and a short recap on complex integral transforms (Fourier, Laplace, F/K and linear Radon). Followed by topics on: - The acoustic wave equation in inhomogenous media - Integral representations of the acoustic wave equation; Kirchhoff-Rayleigh and the Scattering Integral (Lippmann-Schwinger) - The AVO data model; Zoeppritz reflection coefficients - Linear inversion of AVO data including regularisation; synthetic and real data examples - The non-linear data model for inversion; data equation and object equation; iterative, multiplicatively regularised inversion - Applications based on an elastic full-wavefield non-linear data model; realistic synthetic reservoir study, real data case studies including low-frequency model extraction and seismic-to-well matching. Synthetic time-lapse example.

More information

Migration, Velocity Model Building and Updating

Instructor: Mr Piet Gerritsma (Gerritsma Geophysical Training and Consultancy)

The process of migration, whereby a proper image in time or depth of the subsurface is obtained, is directly related with the velocity model that both serves as input for the migration process as well as is the result of such a migration. Therefore migration and velocity model building are intimately related processes and often applied in an iterative mode. This course gives an overwiew with theory and implementation of the representative migration algorithms as well as of the multitude of ways to build and update subsurface velocity models.

More information

The Principles of Quantitative Acoustical Imaging

Instructor: Prof. Dr Dries Gisolf (Delft Inversion)

This course presents a systematic approach to imaging of acoustic reflection data and the extraction of media property information from the image amplitudes, based on wave theory. Although the approach is valid for a wide range of acoustical frequencies and applications, there is a bias towards seismic imaging.

More information