Petrophysical Analysis of Multicomponent Seismic Data

Sergey B. Fomel, principal investigator

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.


For more information, please contact Sergey Fomel, principal investigator. Telephone 512-475-9573;

July 2005