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Full Waveform Inversion for More Accurate Velocity Models

The promise of full waveform inversion (FWI) is to derive high-fidelity Earth models that can be used for more accurate prospect evaluation and reservoir exploitation. The FWI method optimizes the subsurface model estimates by minimizing the difference between field data and simulated data. Our proprietary version of FWI leverages wave-based methodologies to generate fine scale Earth models thereby improving the ability to resolve complex geologies.

The FWI Workflow

ION's FWI solution provides algorithms that characterize the acquired wavefield using models that can be parameterized to include velocity, density, anisotropy, and attenuation. The technology is applied in innovative workflows depending on the characteristics and properties of the subsurface.

In the simplest workflow, a 3D velocity model is updated to match the field data. At a higher level of complexity, for media with strong anisotropy, forward modeling is computed based on acoustic wave equations in vertically transversely isotropic media (VTI).  For geologic environments that strongly attenuate seismic energy, such as gas clouds, the model is updated for attenuation and velocity. Well log data can be used to act as constraints to the inversion of the earth model. Well constraints also stabilize the results of FWI and help accelerate the algorithm to a viable solution.

Beyond the FWI algorithm fidelity, our imaging group has pioneered new workflow efficiencies that ensure data integrity and computational efficiencies throughout iterations.  Source wavelet quality control help validate that synthetic models and field data are optimally matched.  While an irregular shot sampling capability delivers dramatic savings in compute cycles while still delivering high-quality images. 

Benefits of FWI

  • Resolves fine scale features to improve Earth models 
  • Helps resolve complex geologies
  • Complete iterative workflow to ensure image resolution and timing requirements are met
  • Uncompromising quality, built on our two-way, wave equation imaging excellence

Example 1

Standard low-resolution velocity model showing sediment compaction trend before anisotropic FWI.
Standard Low-Resolution
High resolution, anisotropic FWI velocity model showing lateral variations in velocities. Velocity models with this level of detail can be used for complex imaging problems, pore pressure analysis, and detailed impedance inversion.
High-Resolution
(Mouse over image to view High-Resolution
or click to view a side-by-side comparison)

Example 2

Stack image using the initial velocity model and the initial epsilon model before anisotropic FWI.
Initial Velocity
Stack image using the updated velocity model and the updated epsilon model after anisotropic FWI. Notice the higher resolution image with detailed structure above the salt as outlined in the blue box. Note the fault in the structure is delineated more clearly.
Updated Velocity
(Mouse over image to view with Updated Velocity Model
or click to view a side-by-side comparison)