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HORKOWITZ, KATHLEEN O., WILLIAM R. MORRIS, MARK H. SCHEIHING, ARCO Exploration and Production Technology, Plano, TX; and H. DE VILLE WICKENS, Consultant, South Africa

Abstract: 3D Synthetic Seismic Modeling of Turbidite Sandstones

3D synthetic seismic models were generated for a fine-grained, sand-rich turbidite system to illustrate lateral variability in acoustic impedance and seismic response as a function of turbidite facies architecture. The models represent a 250 m exposed section containing 4 stacked turbidite fan complexes from the Karoo Basin, South Africa. The ultimate goal of this work is to aid in seismic interpretation of deepwater turbidite prospects and reservoirs.

Model generation consisted of: 1) construction of the 3D lithostratigraphic framework from detailed outcrop descriptions and gamma ray measurements, 2) calculation and assignment of rock properties representative of consolidated subsurface reservoir sandstones and shales, and 3) generation of the 3D synthetic seismic trace volume.

Acoustic impedance values were calculated using an empirical relationship to estimate P-wave velocity from porosity and clay volume. Synthetic seismic volumes were generated by convolving the reflectivity function derived from the acoustic impedance volume with Ricker wavelets having different peakfrequencies. These models illustrate: 1) the seismic response to changes in thickness and acoustic impedance of the turbidite channel, lobe and overbank facies without hydrocarbon effects, and 2) the ability to resolve the individual fan complexes using different model pulses. 

AAPG Search and Discovery Article #90924©1999 GCAGS Annual Meeting Lafayette, Louisiana