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We are developing new technology for improved multicomponent seismic data analysis. The technology is based
on creating angle gathers for both P-wave and S-wave amplitude-versus-angle (AVA) analysis using new powerful
wave-equation imaging approaches. Unlike traditional amplitude-versus-offset (AVO) gathers, AVA gathers operate
directly in the true reflection angle coordinates, providing a direct assessment for inverting P-wave and S-wave
reflectivity for seismic lithology, porosity, and pore fluid content. A joint inversion of multicomponent data in
the true angle coordinates opens new possibilities for direct detection of natural gas resources by discriminating
between oil, water, and gas content in complex reservoirs during both exploration and production. This technology
facilitates exploration in complex geologic areas, improves oil-and-gas reservoir characterization, increases the
accuracy of petrophysical attributes estimation, and decreases the much higher costs of exploratory drilling and
failed secondary recovery injection projects.
Utilizing 3-D wave-equation migration for seismic imaging is a new approach that has shown great promise in
imaging complex deep-water Gulf of Mexico structures. Previously only so-called Kirchhoff methods could be used
to generate common-reflection point (CRP) gathers in offset domain and iteratively improve the velocity model used
for imaging. Recent research has established a new approach to generating angle-domain common image gathers (ACIG)
directly from 3-D wave-equation methods. ACIG's can be used to update the initial velocity model, and they form the
basis for a novel method of 3-D amplitude analysis. This technology can be used for gas exploration in deep complex
structures over 10,000 ft, where conventional, single-traveltime-arrival, Kirchhoff imaging fails to provide an
accurate structural image and wave-equation imaging provides much higher structural resolution and amplitude fidelity.
The geophysicist can then obtain higher resolution petrophysical information, linking the accurate seismic amplitude
to reservoir properties such as porosity, sand/shale content, water/oil saturation, Vp/Vs ratio, etc. |
