COURSE CONTENT
1. SEISMIC PROPAGATION
- Media for wave propagation
- Types of waves
- Elastic constants
- Factors controlling Poisson’s ratio include:
- Propagation of waves
- Partitioning of energy.
2. ROCK PHYSICS FOUNDATION FOR AVO ANALYSIS: GASSMANN’S EQUATIONS AND FLUID SUBSTITUTION
- Gassmann’s equations
- Gassmann’s assumptions
- Using Gassmann’s equations
- Estimating K*
- The Fluid Substitution Paradox
- Fluid properties
- Raymer-Hunt-Gardner Equations
- Saturated versus frame moduli
- Low gas saturations
- Sensitivity and uncertainty
- Differences in frame modulus from inverted modulus and between brine and gas sands
- Alternatives to Gassmann’s Equations
- Conclusions and Discussion.
3. EARLY SEISMIC OBSERVATIONS: HISTORICAL DEVELOPMENTS LEADING TO THE BIRTH OF AVO
- Introduction
- Bright spot technology before AVO
- Increased understanding of conventional hydrocarbon indicators
- Shear wave exploration
- Other methods
- Birth of AVO
- AVO is widely used and lessons learned
- Studying offset dependence of reflection coefficients with ‘equal-angle particle stacks’
- Classification of AVO anomalies
- Commercialization of AVO
- Bright Spots: Oil versus Gas
- Rock physics analysis and AVO
- The Impact of 3D Seismic
- Crossplotting of AVO attributes
- Lambda-Mu-Rho analysis
- Application of AVO in exploration/development projects
4. ZOEPPRITZ EQUATIONS AND THEIR APPROXIMATIONS
- Bortfeld approximation
- Richards and Frasier (Aki and Richards) approximation
- Shuey’s approximation
- Hilterman’s approximation
- Smith and Gidlow approximation
- Fatti et al approximation
- Lamé parameter extraction
- Xu and Bancroft extraction
- Gray et al extraction
- Approximations for Converted-Wave and Anisotropic Reflectivity.
5. FACTORS AFFECTING SEISMIC AMPLITUDES AND PROCESSING FOR AVO
- Introduction
- Spherical spreading
- Transmission
- Influence of scattering attenuation in heterogeneous overburden on AVO
- Intrinsic attenuation and dispersion
- Mode conversions
- Effects of tuning and NMO stretch
- Removal of noise
- AVO in structurally complex areas
- Anisotropy
- Effects due to receiver coupling
- Effects due to array directivity
- Preprocessing for AVO
- 3-D AVO
- AVO attribute processing
- Estimation of intercept and gradient.
6. AVO INTERPRETATION
- Introduction
- Modeling
- AVO techniques
- Attribute stacks
- AVO combination indicators
- Classification of AVO responses
- Crossplotting
- Noise and AVO
- AVO and visualization
- AVO polarization attributes
- Lambda-Mu-Rho λμρ
- AVO and neural networks.
7. AVO and Anisotropy
- Introduction
- Anisotropy
- Weak anisotropy in rocks
- Physical meaning of anisotropy parameters
- Offset-dependent effects of anisotropy
- Numerical solution to Zoeppritz equations
- Moveout velocity analysis in anisotropic media
- Azimuthal anisotropy
- Methods for fracture analysis
8. SEISMIC INVERSION, CONVERTED WAVE AVO, AND UNCERTAINTY IN AVO ANALYSIS
- Seismic inversion
- Impedance inversion
- Band limited nature of seismic signal
- Sparse-spike inversion
- Model-based inversion
- Elastic impedance
- Local and global optimization in inversion
- Prestack versus poststack inversion
- Simultaneous inversion
- Poisson Impedance.
Converted-wave AVO
- Zoeppritz equations for PS reflections
- PS Elastic Impedance
- Simultaneous P-P and P-S inversion
Uncertainty in AVO
- Bayes theorem
- Monte Carlo simulation
- Quantifying uncertainty
- Quantifying uncertainty in practicen
9. DISCUSSION AND CONCLUSIONS
- Introduction
- AVO Processing Issues
- Aspects of Seismic Data Acquisition for AVO Analysis
- Amplitude Calibration and Balancing
- AVO Attributes and Crossplotting
- The Rigidity Contrast Paradox
- Comments on Class IV Gas Sands
- Dynamic Elastic Moduli Determination
- Azimuthal AVO
- Carbonate AVO
- Tuning and Frequency Dependent AVO
- AVO Risking
- AVO in Practice
- The Future of AVO.