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Note: This module is deprecated. It is retained for compatibility with legacy workflows. For new projects, use the current surface statics solution available in the Statics group.
CalculateSurfaceStaticShifts decomposes residual static errors stored in a static correction item into individual source and receiver surface static shift values. The module sets up a sparse least-squares system in which each trace equation links one source static and one receiver static to the measured residual for that trace. It then solves this system iteratively using a Gauss sparse solver, subject to a user-defined maximum shift bound and convergence criterion.
After the solve, the module computes per-trace residual errors (the portion of the static not explained by the source and receiver shifts) and stores the complete result — source statics, receiver statics, and residuals — in the output static correction item. Two scalar convergence diagnostics (RMS of input residuals and RMS of output residuals) are also produced. Three 2-D map views can be displayed in the viewer to inspect spatial distributions of trace, source, and receiver static values across the survey area.
The input static correction storage containing the traces together with their associated source and receiver geometry and residual static error values. This item is produced by an upstream static analysis step (for example, a refraction or surface-consistent statics module) and must be valid before running this module. The module reads the full-residual static error for every trace and uses the source and receiver sequence numbers to assemble the least-squares equations.
The convergence tolerance for the iterative solver, expressed in seconds. The solver stops early when the change between successive iterations falls below this threshold. Default: 0.002 s. Valid range: 0 to 0.012 s. Use a smaller value (e.g., 0.0005 s) when you require a tighter fit between the solved statics and the input residuals, at the cost of more iterations. For exploratory runs a larger value such as 0.005 s may be sufficient and will converge faster.
The maximum allowed absolute value of any single source or receiver static shift, in seconds. The solver constrains every unknown to lie within the range [−MaxShift, +MaxShift]. Default: 0.06 s. Valid range: 0 to 1 s. Set this value to encompass the expected range of near-surface static anomalies in your survey. If the true statics are larger than this bound, the solver will clip the output and leave unexplained residuals; if it is set too large, the solution may be under-constrained.
The maximum number of iterations the Gauss sparse solver is allowed to perform before stopping, regardless of whether the accuracy criterion has been met. Default: 100. Valid range: 1 to 1000. For large surveys or very tight accuracy requirements, increasing this value gives the solver more opportunity to converge. Compare the Input Convergence and Output Convergence diagnostics after the run: if Output Convergence is still significantly larger than the Accuracy value, increasing iterations may help.
The X coordinate (easting) of the center point of the 2-D static map display grid, in the same coordinate system as the survey geometry. This parameter controls the spatial extent of the viewer maps only and does not affect the static solution. Set this to the approximate X center of your survey area so that sources and receivers are visible in the map views.
The Y coordinate (northing) of the center point of the 2-D static map display grid, in the same coordinate system as the survey geometry. Like CenterX, this parameter affects only the viewer display. Set it to the approximate Y center of your survey area.
The total extent of the map display grid in the X direction (inline), in metres. Default: 10000 m. This value determines how many columns the viewer grid has (DistanceX divided by StepX). Increase it to cover larger surveys; reduce it to zoom into a smaller area of interest. This parameter does not affect the static solution.
The total extent of the map display grid in the Y direction (crossline), in metres. Default: 10000 m. This value determines how many rows the viewer grid has (DistanceY divided by StepY). Set it to match the crossline span of your survey. This parameter does not affect the static solution.
The bin size of the map display grid in the X direction (inline spacing), in metres. Default: 50 m. Static values from all sources or receivers that fall within the same bin are averaged together for display. Use a step size comparable to your source or receiver station interval to produce a meaningful map. Finer steps reveal more spatial detail but may result in many empty bins for sparse surveys.
The bin size of the map display grid in the Y direction (crossline spacing), in metres. Default: 50 m. Analogous to StepX but applied in the crossline direction. Set it to match your crossline station spacing for the most informative display.
The output static correction item containing the solved surface static shifts. For each source point the item stores the solved source static shift (in seconds); for each receiver point it stores the solved receiver static shift (in seconds); and for each trace it stores the residual static that could not be explained by the source and receiver components. This item is passed to downstream modules for application to the seismic data.
The root-mean-square (RMS) of the input residual static errors across all traces, in seconds. This scalar summarises the magnitude of the static problem before the solve. Use it as a baseline to assess how much of the static energy the solver has removed.
The root-mean-square (RMS) of the per-trace residual static errors remaining after the solve, in seconds. A well-converged solution will show Output Convergence significantly smaller than Input Convergence. If Output Convergence is close to Input Convergence, the solver may not have had enough iterations, the MaxShift bound may be too tight, or the data may contain non-surface-consistent static energy.