Circumventing Velocity Uncertainty in Imaging Complex Structures i-Cube
Patent Number: US 11150372 Grant Date: 2021-10-19 Filing Date: 2018-01-05
Overview
This patent protects a practical workflow that synthesizes a zero-offset wavefield from a migration cube to circumvent the persistent problem of velocity uncertainty in complex near-surface and structurally complicated settings. Filed on January 5, 2018 and granted on October 19, 2021, the claims capture a migration-cube → demigration-cube → synthesized zero-offset wavefield sequence that preserves reflections and diffractions without prematurely committing to an rms velocity field. Inventors based in Urla, TR developed a processing chain that includes near-surface modeling via nonlinear traveltime inversion, multi-scale statics correction, multichannel signal enhancement, prestack time migration over a range of constant velocities, demigration, Radon-domain correction, and summation over a velocity axis to yield an unmigrated zero-offset volume suitable for economical poststack time and depth migration.
Our drafting emphasizes both the technical depth — including implementation on computing platforms and Dix conversion for interval velocity estimation — and practical value: the workflow reduces repeated, costly prestack velocity updates while improving event preservation and structural clarity in difficult imaging scenarios.
Key Features
- Synthesizes a zero-offset wavefield from a migration cube to avoid committing to an uncertain rms velocity.
- Demigration and Radon processing preserve diffractions and reduce horizontal smearing.
- Enables efficient poststack time/depth migration and interval velocity estimation via Dix conversion.
This invention improves imaging reliability in exploration and reservoir characterization workflows and reduces computational and operational expense for projects in structurally complex basins.
Invention Details
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.
Summary of the Invention: 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 a 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.
Next, 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.
Patent Document
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