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The Shift Data by Raw Header module reads a SEG-Y file, computes a per-trace time shift from one or more raw trace header byte positions, and writes the shifted traces to a new SEG-Y output file. The shift value for each trace is obtained by evaluating a mathematical expression that combines the raw header values (referenced as $A$, $B$, etc.). This module is designed for workflows where the shift information is encoded directly in the binary SEG-Y headers at specific byte positions and cannot be accessed through the standard trace header mapping.
The computed shift (in ms) is applied to each trace by either linear interpolation or sinc interpolation. The shift can be applied in the forward direction (positive — shifting traces later in time) or reversed (negative — undoing a previously applied shift) to allow bi-directional correction within the same workflow.
The full path and file name of the input SEG-Y file (.sgy or .segy) from which traces will be read. Use the file browser to navigate to the file. All traces in this file will be shifted and written to the output file.
A list of raw trace header fields whose byte values are used to compute the shift. Each entry defines the byte position in the SEG-Y trace header and its data type (e.g., short integer). By default the collection contains two entries at byte positions 98 and 100. The values extracted from these fields are passed to the mathematical expression as variables $A$, $B$, and so on in the order they appear in the list. Add, remove, or edit entries to match the header layout of your SEG-Y files.
A mathematical formula that combines the raw header values to produce the shift amount (in ms) for each trace. The variables $A$, $B$, etc. correspond to the values extracted from the entries in the Collection fields list. For example, the default expression $A$+$B$ sums the two header fields. Standard arithmetic operators (+, -, *, /) are supported.
Default: $A$+$B$.
Controls whether the computed shift is applied forward or in reverse. Two options are available:
Positive — applies the shift in the forward direction, moving trace events to later times. Use this to apply a static correction encoded in the header.
Negative — reverses the shift direction, moving trace events to earlier times. Use this to undo a correction that was applied in a previous processing step.
Default: Positive.
Selects the interpolation method used when the computed shift is a non-integer number of samples. Linear interpolation is fast and sufficient for QC; Sinc interpolation is more accurate and better preserves the wavelet shape for production processing.
Default: Linear.
The full path and file name of the output SEG-Y file (.sgy or .segy) where the shifted traces will be written. The output file has the same number of traces and samples as the input file, with trace headers copied unchanged (only the sample data is shifted).