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Geomage Surface Consistent Statics EXT computes surface-consistent static corrections by cross-correlating seismic traces within a spatial aperture around each CMP location. For every CMP gather, the module stacks neighbouring traces to form a local reference and then estimates the time shift of each trace relative to that reference using cross-correlation. The resolved per-trace shifts are decomposed into source, receiver, and CMP static components through an iterative least-squares solver. The results are written to a binary output file for subsequent application.
Use this module when near-surface velocity variations cause timing misalignments between traces that degrade stack quality. The extended variant supports a multi-scale common-offset aperture strategy, progressively widening the search radius across common-offset iterations to improve robustness on noisy or sparse data. After this module completes, run the companion Geomage Surface Consistent Statics Solver EXT module to apply the computed corrections to the seismic data.
The SEG-Y dataset containing the pre-stack seismic traces to be corrected. Traces must carry valid source and receiver coordinate headers so that the module can build the surface-consistent decomposition. The data is read in CMP order during processing.
An index vector that organises the input traces into CMP gathers. This item is typically produced by an upstream binning or geometry assignment module and provides the efficient trace-access structure needed for the cross-correlation loop.
Number of cross-correlation pass iterations performed for each CMP gather within each common-offset sub-iteration. On each pass the running shift estimate is updated and fed back into the next pass, allowing the solution to converge progressively. Default value: 1. Increase to 2–5 when the initial alignment is poor or when data signal-to-noise is low, at the cost of longer computation time.
Number of iterations used by the least-squares surface-consistent solver to decompose per-trace time shifts into separate source, receiver, and CMP components. More iterations allow the solver to better satisfy all simultaneous equations, especially on large or irregular surveys. Default value: 100. Values below 20 may produce incomplete decomposition; values above 200 rarely improve results further.
Length of the time window (in seconds) used for the cross-correlation between each trace and its local stack. The window must be long enough to contain meaningful signal content but short enough to exclude reflections with very different moveout. Default value: 0.064 s. The effective window length is automatically extended to at least four times the maximum shift value to avoid wrap-around artefacts. Use larger values (e.g., 0.1–0.2 s) on data with a low dominant frequency; use smaller values when high-frequency coherent noise must be avoided.
Maximum allowable static time shift (in seconds) that the cross-correlation is permitted to detect for any single trace. Shifts larger than this value are clipped. Default value: 0.012 s (12 ms). Set this to a value slightly larger than the largest static anomaly expected in the survey area. Excessively large values increase the risk of cycle-skipping; values that are too small will underestimate true statics.
Start of the time gate (in seconds) within each trace that is used for the cross-correlation analysis. Setting this value defines the top of the analysis window and allows the module to focus on a particular reflection zone while excluding mute zones, direct arrivals, or irrelevant shallow noise. Default value: -1 (use the full trace from the beginning). Set to a positive time value to restrict the analysis to a specific depth interval.
End of the time gate (in seconds) within each trace that is used for the cross-correlation analysis. Paired with StartTime, this defines the bottom of the analysis window. Default value: -1 (use the full trace to the end). Set to a positive time value when deep noise or multiple reflections should be excluded from the statics estimation.
Half-aperture in crossline CMP bins used to form the super-gather for local stacking and cross-correlation. For each CMP the module collects traces from the surrounding crossline neighbourhood extending this many bins on each side. Default value: 5 crosslines. Larger values improve stacking fold and robustness on noisy data but increase memory and computation. For 2D data, set this to 0.
Half-aperture in inline CMP bins used to form the super-gather. Works together with CrossLineAperture to define a rectangular neighbourhood of CMPs that are merged before cross-correlation. Default value: 5 inlines. Increase on land data with sparse fold; decrease to preserve lateral resolution of the static solution.
Number of common-offset sub-iterations. On each sub-iteration, the module repeats the full cross-correlation pass using a progressively expanded offset-based aperture radius (controlled by COIterFactor). This multi-scale strategy helps to first resolve short-wavelength statics at narrow apertures and then longer-wavelength components at wider apertures. Default value: 1 (single pass, no expansion). Increase to 2–4 when statics have a broad spatial wavelength or data coverage is uneven.
Initial source-receiver offset aperture (in metres) used to select traces within the super-gather for the common-offset cross-correlation step. Only traces whose source-receiver offset falls within this radius of the reference trace are included in the local stack. Default value: 100000 m (effectively unconstrained). Reduce this value to restrict stacking to near-offset traces, which can improve correlation quality when moveout residuals are present at large offsets.
Initial CMP distance aperture (in metres) used to select traces within the super-gather for the common-offset step. Traces whose CMP location lies within this lateral distance from the current CMP are included. Default value: 100000 m (effectively unconstrained). Decrease this value to focus the stack on spatially close CMPs and suppress statics contamination from distant, geologically different areas.
Multiplicative growth factor applied to both the source-receiver aperture (COSRAperture) and the CMP aperture (COCMPAperture) at the end of each common-offset sub-iteration. A value of 2 doubles both apertures on each successive pass. Default value: 2. This parameter has no effect when COIterCount is set to 1.
Multiplicative scaling factor applied to CMP-related aperture quantities during the solver iterations. This parameter provides additional control over the spatial extent of the CMP stacking neighbourhood across the main iteration loop. Default value: 1 (no growth). Increase beyond 1 to gradually widen the CMP aperture across iterations, which can be beneficial on data with very variable fold.
Integer flag that controls which components are active in the surface-consistent decomposition. The solver separates per-trace time shifts into up to five additive terms: source static, receiver static, CMP static, a CMP super-term, and an offset-dependent term. The SolveType value encodes which of these terms are enabled as a bitmask. Default value: 2. Consult the project documentation or the Geomage statics workflow guide for a full description of each flag value. For most standard surface-consistent statics workflows the default is appropriate.
Path and name of the output binary file (.dat) to which the computed raw static correlation data are written. This file is used as the input to the subsequent Geomage Surface Consistent Statics Solver EXT module. Optionally, a stacked model SEG-Y file is also written alongside this file for quality control. Ensure the target directory exists and is writable before running the module.
When enabled, the module saves an additional SEG-Y file containing the shift-corrected stacked reference traces (the etalon model gather) alongside the main output. This reference stack can be used for visual quality control to verify that the estimated statics have improved trace alignment. Default value: enabled. Disable this option to reduce output file size when QC data is not needed.
When enabled, the cross-correlation equations used in the solver are formulated based on CMP fold statistics only, ignoring source and receiver fold weighting. This simplification can produce a more stable solution on surveys where fold is highly irregular. Default value: enabled. Disable this option on well-sampled surveys where the full surface-consistent decomposition with individual source and receiver weighting is preferred for higher accuracy.