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Book Chapter

9: Earth Modeling in Depth

Published:
January 01, 2001

9.0 INTRODUCTION

Seismic representation of an earth model in depth usually is described by two sets of parameters – layer velocities and reflector geometries. Depth migration is the ultimate tool for delineation of reflector geometries (Chapter 8). If layer velocities are determined accurately, reflector geometries can be recovered by iterative depth migration (Section 8.2). Difficulties in estimating layer velocities with a required level of accuracy make the earth model estimation a challenging task for the geophysicist.

In this chapter, first, we shall discuss practical inversion methods to estimate layer velocities (Sections 9.1, 9.2, and 9.3). Next, by using appropriate combinations of inversion methods, we shall develop strategies to build an earth model (Section 9.4). Finally, we shall use residual moveout analysis and reflection tomography to update an initial model (Section 9.5) and thus obtain a final model that can be used to image the subsurface in depth as discussed in Chapter 8. By being equipped with methods and strategies for interval velocity estimation, model building, and updating (Chapter 9), and depth migration (Chapter 8), we shall then study in Chapter 10 complete case studies for earth modeling and imaging in depth.

Nearly all of the practical methods of layer velocity estimation are based on ray theory, and more specifically, on inversion of seismic traveltimes. Velocity estimation methods include Dix conversion of rms velocities, inversion of stacking velocities, coherency inversion, and analysis of image gathers from prestack depth migration.

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Investigations in Geophysics

Seismic Data Analysis: Processing, Inversion, and Interpretation of Seismic Data

Öz Yilmaz
Öz Yilmaz
Search for other works by this author on:
Society of Exploration Geophysicists
Volume
10
ISBN electronic:
9781560801580
Publication date:
January 01, 2001

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