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Parabolic NMO by picking is an interactive residual moveout analysis and correction module. Rather than applying moveout based on a velocity model, it allows the user to interactively pick time shifts on a semblance panel computed over a range of parabolic residual moveout (RMO) shifts at a reference offset. The picked shift function is then applied as a parabolic (hyperbolic) correction to the gathers. This approach is used to remove residual moveout after primary NMO correction, particularly in depth-domain workflows where small residual curvature remains after migration.
The semblance is computed as a function of time shift at the reference offset; the user picks the optimal shift trend, saves it, and applies it to flatten the gathers. The module supports both time-domain and depth-domain gather correction via separate shift parameters.
The standard seismic data container carrying the CIG gathers on which residual moveout analysis will be performed.
SEG-Y file handle for reading trace data from disk.
Trace header vector providing offset and bin coordinate information.
The CIG gather to be corrected. Connect from the output of an NMO or migration module.
Stack line geometry for 2D surveys.
Crooked line geometry for 2D surveys with non-straight acquisition.
3D bin grid defining inline/crossline layout.
Pre-sorted trace index for ordered gather access.
File path reference identifying the storage location for the parabolic shift picks. Set-only; the path is automatically managed by the module.
Persistent storage item holding the interactively picked parabolic time-shift function. Connect to ensure picks are preserved between runs.
Domain of the input gathers. This is a read-only display field updated automatically from the connected gather.
Internal flag controlling whether the gather domain is read from the connected gather object. Leave at the default (enabled); do not change.
Velocity (m/s) used to replace zero-valued samples at zero offset before applying the parabolic correction, preventing division-by-zero artefacts. Default: 1500 m/s.
Offset distance (m) at which the parabolic shift is defined and displayed on the semblance panel. Default: 1000 m. Set this to a representative far offset for your survey — typically 50–80% of the maximum offset — to make the semblance sensitivity to residual moveout as high as possible at that offset.
Minimum time shift (s) at the reference offset scanned in the semblance panel for time-domain gathers. Default: -0.1 s. This controls the left edge of the semblance scan range. A larger negative value widens the scan range for large residual over-corrections.
Minimum depth shift (m) at the reference offset for depth-domain gathers. Default: -100 m.
Maximum time shift (s) at the reference offset for time-domain gathers. Default: 0.1 s. Extend the range when the residual moveout is large, for example after long-offset PSDM with an imperfect velocity model.
Maximum depth shift (m) at the reference offset for depth-domain gathers. Default: 100 m.
Increment (s) between adjacent shift columns in the time-domain semblance panel. Default: 0.01 s. Reduce for finer semblance resolution at the cost of increased computation time.
Increment (m) between adjacent shift columns for depth-domain semblance. Default: 10 m.
Length (s) of the time-axis smoothing window applied to the semblance panel for time-domain gathers. Default: 0.1 s. Increase to suppress semblance noise at the cost of reduced vertical resolution.
Length (m) of the vertical smoothing window for depth-domain semblance. Default: 100 m.
Normalisation window length (s) for time-domain semblance. Default: 0.2 s. A longer window makes the semblance less sensitive to short isolated events and more representative of overall moveout quality.
Normalisation window length (m) for depth-domain semblance. Default: 200 m.
When enabled, the parabolic correction is applied to the gather display in real time as picks are updated interactively. Default: off. Enable for immediate visual feedback during picking, at the cost of increased processing load per pick update.
When enabled, input data items are automatically connected from the nearest upstream module with matching output types.
Specifies how to handle NaN or Inf sample values in the input data.
Selects the processing device. CPU is standard for this module.
Configuration for distributed (cluster) execution.
Minimum number of gathers sent per work chunk during distributed execution.
When enabled, restricts CPU thread count per cluster node to the value in Number of threads.
Optional text appended to the distributed job name.
When enabled, applies the CPU affinity mask specified in Affinity.
CPU affinity mask applied when Set custom affinity is enabled.
Maximum number of CPU threads used during execution.
When enabled, this module is bypassed and data passes through unchanged.
The residual-moveout-corrected seismic data container. Pass to downstream stacking or inversion modules.
SEG-Y file handle for writing the corrected output to disk.
Trace headers corresponding to the corrected output traces.
The corrected gather with parabolic residual moveout removed.
Stack line geometry passed through from input.
Crooked line geometry passed through from input.
Bin grid passed through from input.
Sorted trace index passed through from input.
Recomputes and refreshes the semblance panel for the currently selected bin, incorporating any changes to the scan range or smoothing parameters.
Removes all parabolic shift picks from all bins. Use before re-picking with updated parameters.
Loads previously saved parabolic shift picks from the velocity picking item.
Saves the current parabolic shift picks to the velocity picking item for persistence between sessions.