Circumventing Velocity Uncertainty in Imaging Complex Structures i-Cube
OwnerÖzdogan Yilmazinventor
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Abstract
A zero-offset wavefield synthesis workflow to calculate a synthesized zero-offset wavefield output without the commitment to an rms velocity field output to circumvent velocity uncertainty. Said zero-offset wavefield synthesis workflow comprises calculating a migration cube output. Rendering a demigration cube output from said migration cube output with a demigration cube calculation. Rendering said synthesized zero-offset wavefield output from said demigration cube output with a zero-offset wavefield synthesis procedure.
Claims20
A zero-offset wavefield synthesis workflow to calculate a synthesized zero-offset wavefield output without the commitment to an rms velocity field output to circumvent velocity uncertainty, comprising:
- calculating a migration cube output with a migration cube procedure by
- estimating a model for the near-surface by nonlinear traveltime inversion applied to first-arrival times picked from shot gathers and calculate the medium- to long-wavelength shot-receiver statics,
- applying shot-receiver statics and an appropriate single-channel signal processing sequence to shot records,
- estimating a short-wavelength shot-receiver residual statics based on stack-power optimization,
- apply said short-wavelength shot-receiver residual statics to moveout-corrected CMP gathers,
- performing multichannel signal enhancement in the CMP domain,
- returning to the shot-receiver domain and perform additional multichannel signal enhancement to further attenuate coherent linear noise and random noise,
- performing prestack time migration of all shot gathers using a range of constant velocities, and
- obtaining a set of a velocity panels that form said migration cube output;
- rendering a demigration cube output from said migration cube output with a demigration cube calculation;
- and
- rendering said synthesized zero-offset wavefield output from said demigration cube output with a zero-offset wavefield synthesis procedure.
A zero-offset wavefield synthesis workflow to calculate a synthesized zero-offset wavefield output without the commitment to an rms velocity field output to circumvent velocity uncertainty, comprising:
- calculating a migration cube output with a migration cube procedure by
- estimating a model for the near-surface by nonlinear traveltime inversion applied to first-arrival times picked from shot gathers and calculate the medium- to long-wavelength shot-receiver statics,
- applying shot-receiver statics and an appropriate single-channel signal processing sequence to shot records,
- estimating a short-wavelength shot-receiver residual statics based on stack-power optimization,
- apply said short-wavelength shot-receiver residual statics to moveout-corrected CMP gathers,
- performing multichannel signal enhancement in the CMP domain,
- returning to the shot-receiver domain and perform additional multichannel signal enhancement to further attenuate coherent linear noise and random noise,
- performing prestack time migration of all shot gathers using a range of constant velocities, and
- obtaining a set of a velocity panels that form said migration cube output;
- rendering a demigration cube output from said migration cube output with a demigration cube calculation;
- rendering said synthesized zero-offset wavefield output from said demigration cube output with a zero-offset wavefield synthesis procedure;
- said demigration cube output comprises an unmigrated volume that contains all reflections and diffractions that are present in the signal-processed shot gathers;
- estimating said rms velocity field output by limiting estimates within the bounds of time migration;
- and
- said rms velocity field output comprises a one or more lateral velocity variations.
A zero-offset wavefield synthesis workflow to calculate a synthesized zero-offset wavefield output without the commitment to an rms velocity field output to circumvent velocity uncertainty, comprising:
- calculating a migration cube output with a migration cube procedure by
- estimating a model for the near-surface by nonlinear traveltime inversion applied to first-arrival times picked from shot gathers and calculate the medium- to long-wavelength shot-receiver statics,
- applying shot-receiver statics and an appropriate single-channel signal processing sequence to shot records,
- estimating a short-wavelength shot-receiver residual statics based on stack-power optimization,
- apply said short-wavelength shot-receiver residual statics to moveout-corrected CMP gathers,
- performing multichannel signal enhancement in the CMP domain,
- returning to the shot-receiver domain and perform additional multichannel signal enhancement to further attenuate coherent linear noise and random noise,
- performing prestack time migration of all shot gathers using a range of constant velocities, and
- obtaining a set of a velocity panels that form said migration cube output;
- rendering a demigration cube output from said migration cube output with a demigration cube calculation;
- rendering said synthesized zero-offset wavefield output from said demigration cube output with a zero-offset wavefield synthesis procedure;
- performing multichannel signal processing to each of said velocity panels of said migration cube procedure to increase signal coherency;
- said migration cube output comprises image volume in (V, X, T) coordinates;
- said V comprises an rms velocity;
- said X comprises a midpoint;
- said T comprises an event time after migration;
- demigrating each of said velocity panels within said migration cube output using said range of constant velocities;
- and
- creating said demigration cube output.
Dependencies are inferred from the claim text.