Elements of 3D Seismology: Introduction to Interpretation

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Elements of 3D Seismology:Introduction to Interpretation

Christopher L. LinerUniversity of Tulsa

November 2003

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Synthetic Seismogram

Assume: Zero offset, zero dip, and v(z)

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Synthetic Seismogram

•Travel times•Layer thickness and velocity

•Reflection coefficients•Velocity and density

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Synthetic Seismogram

•R0 is important•Reflection coefficient•Normal incidence (zero offset)•Values [-1,+1]

•Commonly [-.3,.3]•I = acoustic impedance

•Rock property influences•Mineralogy•Porosity•Pore fluid

•Seismic peak amplitude ~ R0

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Synthetic Seismogram

Wavelet

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Synthetic Seismogram

Wavelet

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Synthetic Seismogram

Is peak amplitude ~ R0 …. ?Modeling can supply the answer.

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(A)Field data stack(B) Stack of Z.O. synthetic(C) Detail of B(D)Gamma log(E) AVO synthetic

(F) Resistivity log(G) Bulk density log(H) P-wave sonic(I) S-wave sonic(J) Vp/Vs ratio

Lindsay and Koughnet, 2001, TLE

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Tuning

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Tuning

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Vertical Resolution

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Vertical Resolution

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Tuning and Resolution

Tuning and resolution thickness are equal– Wavelength/4 = v/(4 f)– v is interval velocity of the thin bed– f is dominant, or average, frequency

• About 20-40 Hz

Subresolution thickness mapping– Difficult because top/base events commingle– Tools

• Tuning curves, spectral decomposition,+

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