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Oil & Gas Training
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Competency Management system SLB NEXT

Tomography and Anisotropy with Omega

This course is designed for geoscientists with an understanding of basic seismic processing theory including depth imaging, model building and ray theory who have some practical experience of building models for depth imaging and who wish to learn the more advanced aspects of tomographic model updating and how to use well data and incorporate anisotropy into a depth model.

There are four main topics: Tomographic inversion, loading and using well data in model building, Q tomography and Anisotropy.

The attendee will learn how to prepare input data for tomography and run and QC the results using Omega and Petrel, how to load basic well data and use it in model building, Q-tomography and how to update an inverse Q model and understand anisotropy including VTI, TTI, HTI and orthorhombic and how to derive and update anisotropy in depth imaging model building. Each topic is introduced with some background material which includes discussion of theory and applications. This is followed by an explanation of the workflow, data requirements and a step by step discussion of the procedures to execute the workflows. Where possible there are practical exercises to provide hands on experience in executing the workflows.

Day 1

Recap and introduction to CIP tomography for marine data

  • How reflection tomography works
  • The tomography workflow in Omega
  • Overview of tomography course content
  • Preparing gathers for RMO picking (start)

At the end of this session the student will be able to explain how reflection tomography works in theory and the basic reflection tomography workflow. They will be able to explain the considerations for input data for RMO picking, identify the events to pick and test far trace mutes, demultiple and band-pass filters.             

Day 2

Depth Gather Preparation and RMO Picking, Ray-tracing Illumination and Dip Fields

  • Preparing depth gathers for RMO picking (contd.)
  • How CIP_PICK works
  • RMO QC
  • How CIP_DIFF works
  • Generating dip fields for CIP_DIFF
  • Generating dip fields for ZTOMO and for TTI anisotropy

Students will be able to explain how CIP_PICK and CIP_DIFF work in theory, run RMO QC, run CIP_DIFF in practice and QC CIP_DIFF rays in Petrel. They will be able to generate and QC dip fields for CIP_DIFF and generate dip fields for ZTOMO steering filters.

Day 3

ZTOMO Functionality

  • Using smoothing filters and steering filters in ZTOMO
  • Testing additional ZTOMO parameters
  • Using bounded updates in tomography

At the end of this session student will be able to choose ZTOMO parameters, especially filter lengths and QC steering filters and velocity updates. They will be able to test damping factors, pick weighting and explain automatic decision making. They will be able to create a model for bounded updates and run ZTOMO for bounded updates.             

Day 4

Multi-Azimuth and High Resolution Tomography, Well Constraint Tomography and Event Matching

  • Running multi-azimuth tomography
  • Running high resolution tomography
  • Using tomography to tie model depths to well depths
  • Using tomography to match one event to another

Students will learn how to prepare datasets, QC the illumination, parameterize ZTOMO and QC the velocity update. They will learn when to use high resolution tomography, explain the density of RMO picks, model sampling and choice of ZTOMO parameters. They will learn when to use tomography to tie model depths to well depths and matching one event to another and the parameterization involved with these options.

Day 5

Multi-Attribute Tomography and Localized Tomography

  • Updating more than one model attribute using tomography
  • Running localized tomography

Students will be able to explain when to use this functionality, which parameters can be updated, what data is needed to adequately constrain the tomography and the parameterization of CIP_DIFF and ZTOMO.

Day 6

Q-Tomography

  • The Q-tomography workflow in Omega
  • Building and initial Q model
  • Running Q-tomography

Students will be able to explain when to use this functionality, what the basic Q-tomography workflow is and the SFMs that are used. They will also learn the methods to derive effective Qs from the data and how to parameterize Q-tomography when compared to conventional CIP tomography.

Day 7

Q-Tomography

  • The Q-tomography workflow in Omega
  • Building and initial Q model
  • Running Q-tomography

Students will be able to explain when to use this functionality, what the basic Q-tomography workflow is and the SFMs that are used. They will also learn the methods to derive effective Qs from the data and how to parameterize Q-tomography when compared to conventional CIP tomography.

Day 8

Recap and Introduction to Anisotropy, Deriving/Verifying Anisotropy with Wells and VSPs

  • What is anisotropy?
  • How anisotropy affects depth imaging
  • Overview of anisotropy course content
  • Loading well data
  • Deriving/verifying anisotropy using SeisCal in Omega and Petrel

At the end of this session the student will be able to explain what anisotropy is and also the different types, how it affects depth imaging and how it is used in models.

Day 9

Deriving/Verifying Anisotropy with Wells and VSPs continued

  • Deriving/verifying anisotropy using VSP traveltime data
  • Anisotropy using more than one will, spatially varying anisotropy
  • TTI anisotropy
  • Review of the methods used to update anisotropy and considerations during model updating

Students will learn how to build a 3D anisotropy field, and explain the differences between VTI and TTI anisotropy. They will learn how to update anisotropy and decide when to use each method.

Day 10

Deriving/Verifying Anisotropy using Eta Fields and Other Methods

  • Relationship of eta to delta and epsilon
  • Picking eta functions using InVA
  • Generating eta fields using VIVA
  • Creating epsilon fields from eta fields
  • Using regional anisotropic trends and geological knowledge
  • Deriving anisotropic values using rock physics

At the end of this session students will be able to explain how eta is normally used for time imaging and its relationship to depth imaging delta and epsilon properties. The student will be able to prepare seismic data for eta picking, manually pick eta functions in InVA, QC the eta field and explain the limitations of eta picking.  

Learning activity mix

Geoscientists involved in data processing with knowledge of seismic processing techniques and some practical experience of building models for depth imaging wishing to learn the more advanced aspects of tomographic model updating and how to use well data and incorporate anisotropy into a depth model.

There are four main topics: Tomographic inversion, loading and using well data in model building, Q tomography and Anisotropy.

This training assumes that attendees have experience working with Omega and Petrel SVM and also:

  • Familiarity with basic theory and fundamentals of marine data processing and depth imaging.
  • Have completed training courses or a have a good working knowledge of the concepts taught in
    • Introduction to Depth Imaging with Omega
    • Petrel Fundamentals

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