REFERENCES

• Aki, K., and Richards, P. G., 1980, Quantitative seismology: W. H. Freeman and Company.

• Beylkin, G., 1985, Imaging of discontinuities in the inverse scattering problem by inversion of a causal generalized Radon transform: J. Math. Phys., 26, 99-108.

• Beydoun, W. B., and Mendes, M., 1989, Elastic ray-Born l-2 migration/inversion: Geophys. J., 97, 151-160.

• Bleistein, N., 1987, On the imaging of reflectors in the earth: Geophysics, 52, 931-942.

• Crase, E., Pica, A., Noble, M., McDonald, J., and Tarantola, A., 1990, Robust elastic nonlinear waveform inversion: application to real data: Geophysics, 55, 527-538.

• Cunha Filho, C., 1992, Elastic modeling and migration in earth models: Ph.D. thesis, Stanford University.

• de Bruin, C., 1992, Linear AVO inversion by prestack depth migration: Ph.D. thesis, Delft University, The Netherlands.

• De Nicolao, A., Drufuca, G., and Rocca, F., 1991, Eigenvectors of linearized elastic inversion: 61st Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 1017-1020.

• Kjartansson, E., 1979, Attenuation of seismic waves in rocks and applications in energy exploration: Ph.D. thesis, Stanford University.

• Lumley, D. E., and Beydoun, W. B., 1991, Elastic parameter estimation by Kirchhoff prestack depth migration/inversion: Stanford Expl. Proj. Report, 70, 165-192.

• Lumley, D. E., 1992a, Estimation of elastic specular reflectivity by Kirchhoff prestack depth migration: WKBJ least-squares theory: Stanford Expl. Proj. Report, 75, 355-368.

• Lumley, D. E., 1992b, Monte Carlo automatic velocity picks: Stanford Expl. Proj. Report, 75, 1-20.

• Lumley, D. E., and Biondi, B., 1992, Kirchhoff 3-D prestack time migration on a massively parallel supercomputer: 54th Ann. Meeting of the Eur. Assoc. of Expl. Geophys., Expanded Abstracts, 286-287.

• Lumley, D. E., 1993, Angle-dependent reflectivity estimation: Stanford Expl. Proj. Report, 77, this report.

• Nur, A., 1989, Four dimensional seismology and (true) direct detection of hydrocarbons: The petrophysical basis: The Leading Edge, 9, 30-36.

• Parsons, R., 1986, Estimating reservoir mechanical properties using constant offset images of reflection coefficients and incident angles: 56th Annual Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts.

• Tarantola, A., 1986, A strategy for nonlinear elastic inversion of seismic reflection data: Geophysics, 51, 1893-1903.

 

cmps-ann
Figure 3 CMP gathers at surface positions 1 km and 2 km. Note the bright AVO response at 2.3 seconds due to the gas reservoir at depth.

 

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Figure 4 Stacked section structural image. The bright reflectors at 2.3 seconds are associated with a gas production reservoir interval.

 

vscans-ann
Figure 5 Migration velocity semblance scans at surface midpoint positions 1 km and 2 km. The overlain curves are the automatic Monte Carlo velocity picks.

 

migvel
Figure 6 Migration velocity field, obtained by picking 100 migration semblance scans and slight smoothing.

 

crps-ann
Figure 7 Migrated CRP (Common Reflection Point) reflectivity gathers. The top panel is at surface location 1 km, the lower panel at 2 km. The midpoint coordinate direction is perpendicular to the plane of the page.

 

thetas
Figure 8 Migrated CRP reflection angle gathers. Reflection angle contours range from $5^{^{\circ}}$ at near offsets to $30^{^{\circ}}$ at far offsets, in $5^{^{\circ}}$ intervals.

 

mig-ann
Figure 9 Migrated structural image obtained by stacking the migrated CRPs over offset.

 

Pimp-ann
Figure 10 P impedance contrast section.

 

Simp-ann
Figure 11 S impedance contrast section.

 

Dens-ann
Figure 12 Density contrast section.

 

PSmapC
Figure 13 P*S impedance anomaly section. Note the bright anomaly, probably due to increased gas saturation, near the surface midpoint position at 2 km.