Method for controlled-amplitude prestack time migration of seismic data
AssigneeExxonMobil Upstream Research Company
InventorsChristopher J. Finn, Graham A. Winbow
Life of this patent
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Abstract
A method for controlled-amplitude prestack time migration of seismic data traces. According to the inventive method, common-offset gathers of the prestack seismic data traces are 3-D Fourier transformed from the space-time domain to a preselected alternate data domain, such as the frequency-wavenumber domain, the wavenumber-time domain, or the slant-stack domain. A migration operator that substantially preserves the seismic amplitudes of the original data traces is computed in the {right arrow over (p)}−z domain. This migration operator is applied to the transformed data traces in the alternate data domain, an imaging condition is applied, and the resulting migrated data traces are then transformed back to the space domain.
Claims14
A method for prestack time migration of common-offset seismic data traces, said method comprising the steps of:
- selecting a seismic velocity function for use in said prestack time migration;
- transforming said common-offset seismic data traces from the space-time domain to the ω−{right arrow over (k)} domain;
- using said seismic velocity function to compute a time function in the {right arrow over (p)}−z domain for accurately migrating said seismic data traces;
- computing a weighting function in the {right arrow over (p)}−z domain, which weighting function substantially preserves the seismic amplitudes of said seismic data traces;
- using said time function to phase shift said seismic data traces in said alternate data domain;
- multiplying the amplitudes of said phase-shifted seismic data traces by said weighting function;
- forming an image in said alternate data domain by summing said phase-shifted and amplitude-weighted data traces over frequency (ω);
- and
- performing a 2-D transformation of said image from said alternate data domain back to the space domain.
A method for prestack time migration of common-offset seismic data traces, said method comprising the steps of:
- selecting a seismic velocity function for use in said prestack time migration;
- performing a 3-D Fourier transformation of said common offset seismic data traces from the space-time ({circumflex over (ζ)}−t) domain to the wavenumber-frequency (ω−{right arrow over (k)}) domain;
- using said seismic velocity function to compute a time function in the {right arrow over (η)}−z domain for use in migrating said seismic data traces;
- computing a weighting function in the {right arrow over (η)}−z domain, which weighting function substantially preserves the seismic amplitudes of said seismic data traces;
- for every z, performing 2-D transformations of said time function and said weighting function from the {right arrow over (η)}−z domain to the {right arrow over (p)}−z domain;
- using said {right arrow over (p)}−z domain time function to phase shift said ω−{right arrow over (k)} domain data traces;
- multiplying the amplitudes of said phase-shifted ω−{right arrow over (k)} domain data traces by said {right arrow over (p)}−z domain weighting function;
- forming an image in the {right arrow over (k)}−z domain by summing said phase-shifted and amplitude-weighted ω−{right arrow over (k)} domain data traces over frequency;
- and
- performing a 2-D Fourier transformation of said image from the {right arrow over (k)}−z domain to the {right arrow over (x)}−z domain.
Dependencies are inferred from the claim text.