Description

Header statistics computes a summary value - the minimum, maximum, or average - of a selected trace header across all traces that belong to the same gather group, and writes that value back into every trace of the group under a header name you choose. The grouping is not defined by this module itself; it is inherited from an earlier sorting or binning step in the flow (for example, grouping by CDP, shot, or receiver line). Use this module for quality control, such as checking the minimum and maximum offset or elevation within each gather, or to create a representative per-gather value (average source elevation, average fold, maximum absolute offset, and so on) that later steps can filter, color by, or QC against. Several statistics can be computed in a single run by adding more rows to the parameter table, each with its own input header, statistic type, and output header name.

Input data

Input traces

The seismic traces to analyze, together with their trace headers. Header statistics reads the header field you select in the parameters and does not modify the trace samples themselves - only header values are read and, on output, written.

Gather index

Defines how the input traces are grouped into gathers (for example by CDP, shot point, or receiver line) before statistics are computed. This grouping is normally produced by a preceding sorting or binning step in the flow. Header statistics computes one independent set of statistics per group defined here - it never mixes values across groups or computes a single statistic over the whole dataset.

Parameters

Input trace headers

A table where each row defines one statistics computation: which header to read, which statistic to compute, and which header to write the result into. Add one row per header/statistic combination you need; all rows are evaluated together in the same pass over the data.

Input header

Selects the trace header field whose values will be examined within each gather group. The list includes all standard trace headers (such as offset, CDP number, source and receiver coordinates, or elevation) as well as any additional headers already present in the dataset from earlier processing steps.

Default: none (must be selected). Choose the header that reflects what you want to QC or summarize, for example offset to check gather aperture, or elevation to check topography consistency within a shot.

Statistics type

Chooses which statistic is computed from the values of the selected input header across all traces in each gather group. Available options are Min (the smallest value in the group), Max (the largest value in the group), and Average (the arithmetic mean of all values in the group).

Default: Min. Use Min or Max to flag outliers or check coverage limits (for example the minimum and maximum offset per CDP), and Average to derive a representative value for the group (for example mean source elevation per shot).

Output header

The name of the trace header that will receive the computed statistic. The same value is written into every trace belonging to the corresponding gather group. Enter the name of an existing header to overwrite it, or type a new name to create an additional header that later steps in the flow can reference (for example for filtering, sorting, or display purposes).

Default: empty (must be entered). Use a descriptive name that indicates both the source header and the statistic, for example OffsetMax or ElevAvg, so the meaning stays clear later in the flow.

Output data

Output traces

A copy of the input traces with the computed statistic values written into the output header(s) defined in the parameter table. Every trace within the same gather group carries the same value, so downstream steps can compare individual traces against their gather's minimum, maximum, or average - for example to flag traces whose offset departs from the gather average, or to display per-gather elevation trends.