PGS uses broadband 4D NRMS criteria to detect and compensate for small time misalignments as small as 1/20 of a sample, thereby optimizing 4D repeatability. Best results are achieved on broadband multisensor datasets processed to recover the ghost-free up-going wavefield.
- Uses broadband-specific NRMS criteria
- Time deformations can be constrained by the dominant frequency of each wavelet
- Allows the detection of very small 4D time misalignments (about 1/20 of a sample)
- Can be applied as global or semi-global corrections
- Optimizes 4D repeatability
Customized to Broadband 4D Data Characteristics
The traditional least-squares minimization criteria used by warping corrections are replaced by a Normalized RMS (NRMS) formulation customized for broadband 4D data. Parameters such as signal-to-noise ratio (SNR), RMS amplitude ratio, time-shift and dominant frequency are each decomposed from the data. By minimizing this broadband NRMS estimation, the resulting time-deformation can be constrained by the dominant frequency of the wavelet and the associated noise level.
4D dynamic warping corrections are used in processing as a final global or semi-global matching to improve the 4D repeatability. Careful QC is applied to ensure the preservation of genuine 4D signal.
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