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Book Chapter

11: Reservoir Geophysics

Published:
January 01, 2001

11.0 INTRODUCTION

In Chapter 8, we reviewed the two-dimensional (2-D) and three-dimensional (3-D), post- and prestack migration strategies for imaging the earth's interior in depth. In Chapter 9, we learned traveltime inversion techniques for estimating a structural model of the earth that is needed to obtain an accurate image in depth. In Chapter 10, structural inversion case studies for earth modeling and imaging in depth were presented. By structural inversion, we define the geometry of the reservoir unit, and the overlying and underlying depositional units. Traveltimes, however, are only one of the two components of recorded seismic wavefields; amplitudes are the other component.

In this chapter, we shall turn our attention to inversion of reflection amplitudes to infer petrophysical properties within the depositional unit associated with the reservoir rocks. The petrophysical properties include porosity, permeability, pore pressure, and fluid saturation. Specifically, we shall discuss prestack amplitude inversion to derive the amplitude variation with offset (AVO) attributes (Section 11.2) and poststack amplitude inversion to estimate an acoustic impedance model of the earth (Section 11.3). The processes of estimating the acoustic impedance and AVO attributes by way of inversion of amplitudes may be appropriately referred to as stratigraphic inversion. Our goal ultimately is reservoir characterization based on structural and stratigraphic inversion of seismic data with calibration to well data.

We appropriately begin this chapter by investigating the resolution we can achieve from seismic data in defining vertical and lateral variations in the geometry of the reservoir unit. Resolution is the ability to separate two events that are very close together (Section 11.1). There are two aspects of seismic resolution: vertical (or temporal) and lateral (or spatial). Seismic resolution becomes especially important in mapping small structural features, such as subtle sealing faults, and in delineating thin stratigraphic features that may have limited areal extent.

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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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