HR: 1330h
AN: S42E-0221    [PDF]
TI: Stratigraphic imaging of sub-basalt sediments using waveform tomography of wide-angle seismic data
AU: * Sain, K
EM: kalachandsain@yahoo.com
AF: National Geophysical Research Institute, Uppal Road, Hyderabad, A.P 500 007 India
AU: Gao, F
EM: fcgao@rice.edu
AF: Rice University, 6100, Main Street, Houston, TX 77005 United States
AU: Pratt, G
EM: pratt@geol.queensu.ca
AF: Queen's University, Kingston, Ontario, K7L 3N6 Canada
AU: Zelt, C A
EM: czelt@rice.edu
AF: Rice University, 6100, Main Street, Houston, TX 77005 United States
AB: The oil industry is interested in imaging the fine structures of sedimentary formations masked below basalt flows for commercial exploration of hydrocarbons. Seismic exploration of sediments hidden below high-velocity basalt cover is a difficult problem because near-vertical reflection data are contaminated with multiples, converted waves and scattering noise generated by interbeds, breccia and vesicles within the basalt. The noise becomes less prominent as the source-receiver offset increases, and the signals carrying sub-surface information stand out at the wide-angle range. The tomography of first arrival traveltime data can provide little information about the underlying low-velocity sediments. Traveltime inversion of wide-angle seismic data including both first arrivals and identifiable wide-angle reflected phases has been an important tool in the delineation of the large-scale velocity structure of sub-basalt sediments, although it lacks the small-scale velocity details. Here we apply 2-D full-waveform inversion ("waveform tomography") to wide-angle seismic data with a view to extracting the small-scale stratigraphic features of sedimentary formations. Results from both synthetic data, generated for a realistic earth model, and field dataset from the basalt covered Saurashtra peninsula, India, will be presented. This approach has potential to delineate thin sedimentary layers hidden below thick basalt cover also, and may serve as a powerful tool to image sedimentary basins, where they are covered by high-velocity materials like basalts, salts, carbonates, etc. in various parts of the world.
DE: 7203 Body wave propagation
DE: 7205 Continental crust (1242)
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting