Description

Trim statics - Advanced computes and applies short-period residual time (or phase) shifts to individual traces within a gather in a single combined module. It cross-correlates each trace against a reference (optionally a super-gather) within a user-defined time window, then directly applies the estimated shifts to the trace amplitudes, producing an aligned output gather without a separate apply step.

Two shift modes are available. In Time mode the best-fitting integer or sub-sample time shift is found for each trace by standard cross-correlation. In Phase mode a constant-phase rotation (in degrees) is estimated and applied instead of a time delay, which is more appropriate when the residual is primarily a phase error rather than a timing error. Use this module in pre-stack QC workflows where gather alignment needs to be improved before stacking or AVO analysis.

Input data

Input DataItem

The primary seismic dataset whose gathers are to be aligned. Connect the output of the preceding processing module here.

Input SEG-Y data handle

SEG-Y file handle for the primary dataset, propagated downstream.

Input trace headers

Trace header table for the primary dataset, propagated downstream.

Input gather

The current gather from the processing sequence. Static estimation and correction are performed gather by gather.

Input stack line

Stack line passed through to downstream modules.

Input crooked line

Crooked-line geometry definition for 2D surveys, passed through.

Input bin grid

3D bin-grid definition, passed through.

Input sorted headers

Pre-sorted trace index, passed through.

SuperGather

Optional super-gather formed by stacking adjacent CMPs, used as the cross-correlation reference. When connected, the super-gather provides a higher signal-to-noise reference than a stack of only the current gather, improving static estimation quality on low-fold or noisy data.

Parameters

From time

Start of the analysis window, in seconds. Default: 0.1 s. Set this to the top of the target zone, typically below any noisy shallow arrivals or refracted energy.

To time

End of the analysis window, in seconds. Default: 3.0 s. Set this to the base of the zone containing the primary reflectors of interest.

Time window

Length of the cross-correlation sub-window, in seconds. Default: 3.0 s. A longer window averages more reflectors and yields more stable estimates; a shorter window can resolve time-varying statics but is more susceptible to noise.

Trace window

Half-width (in traces) of the local reference formed from neighbouring traces. Default: 0 (use the full gather stack). A non-zero value creates a local reference from adjacent traces, improving performance on gathers with strong amplitude variation across offset.

Median

Half-width of the median filter (in traces) applied to the estimated static field after each iteration. Default: -1 (disabled). A positive integer value suppresses isolated outlier shifts while preserving genuine short-wavelength variation. A value of 1–3 is typically sufficient.

Sort by offset

When enabled, traces are sorted by offset before cross-correlation. Default: off. Sorting improves spatial consistency of the local reference when the Trace window option is used.

Shift type { Phase, Time }

Selects whether residuals are corrected as time shifts or phase rotations. Default: Time.

Time mode finds the time shift (within ±Max time shift) that maximises the cross-correlation between each trace and the reference. The Angle step parameter is not used in this mode.

Phase mode finds the constant phase rotation (in the range −180° to +360°, stepped by Angle step) that maximises the cross-correlation between each trace and the reference. The Max time shift parameter is not used in this mode. Phase mode is appropriate when the residual error is predominantly a phase mismatch rather than a timing offset.

Interpolation type { 8-points, Linear }

Sub-sample interpolation method used when applying the time shift correction. Default: 8-points. The 8-points (sinc) interpolation provides sub-sample accuracy and is recommended for most workflows. Active only when Shift type is Time.

Angle step

Step size for the phase rotation search, in degrees. Default: 5°. Active only when Shift type is Phase. Smaller values improve angular resolution but increase computation time. Values of 1–5° are typically sufficient for most phase correction applications.

Max time shift

Maximum allowable trim static time shift, in seconds. Default: 0.025 s. Active only when Shift type is Time. The cross-correlation search is constrained to the range [−MaxShift, +MaxShift]. Set to slightly exceed the expected maximum residual static. Too large a value increases the risk of cycle-skip errors on noisy gathers.

Number of iterations

Number of cross-correlation and application iterations. Default: 3. After each iteration the estimated shifts are applied to the gather and the reference stack is recomputed, progressively improving alignment. Values of 3–5 are typical; additional iterations yield diminishing returns.

Settings

Auto-connection

When enabled, g-Platform automatically connects compatible data items from the preceding module. Disable to wire connections manually.

Bad data values option { Fix, Notify, Continue }

Determines how the module responds to NaN or infinity values in the input. Fix replaces bad values with zero. Notify logs a warning and continues. Continue silently proceeds.

Execute on { CPU, GPU }

Selects the compute device. CPU is the default and available on all systems.

Distributed execution

Options for distributing processing across multiple cluster nodes.

Bulk size

Minimum number of gathers dispatched to each node as a single work unit.

Limit number of threads on nodes

Caps the number of threads per cluster node to avoid resource contention.

Job suffix

Text appended to the distributed job name for identification in cluster queues.

Set custom affinity

Enables manual CPU core affinity for processing threads.

Affinity

CPU core or core range to which threads are pinned. Active only when Set custom affinity is enabled.

Number of threads

Number of parallel CPU threads. Set to 0 to use all available cores.

Skip

When enabled, the module is bypassed and the input gather passes through unchanged. Useful for comparing aligned and unaligned gathers.

Output data

Output DataItem

The primary output dataset with trim statics already applied to the trace amplitudes.

Output SEG-Y data handle

SEG-Y file handle propagated downstream.

Output trace headers

Trace header table propagated downstream.

Output gather

The time- or phase-corrected output gather, ready for stacking, AVO analysis, or further processing.

Output stack line

Stack line passed through unchanged.

Output crooked line

Crooked-line definition passed through unchanged.

Output bin grid

Bin grid passed through unchanged.

Output sorted headers

Sorted trace index passed through unchanged.

Information

Graphics

Custom actions