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PZ - Apply applies a pre-computed PZ summation operator to the vertical geophone (Z) component of ocean-bottom seismic (OBS) data to attenuate the receiver-side ghost reflection and enhance the up-going wavefield. The operator is produced by the companion module PZ - Calculate and encodes the frequency- and receiver-dependent filter needed to combine the pressure (P) and vertical velocity (Z) components optimally.
Depending on how the PZ operator was calculated, the module applies it either as a matched spectral filter (Stack matching method) or in the frequency-wavenumber (FK) domain (FK analysis method), handling any sample-rate or length mismatch between the input data and the stored operator automatically by resampling both to a common grid. The result is a deghosted Z-component gather ready for further processing and stacking.
Use this module after PZ - Calculate in any OBS processing sequence that requires receiver ghost removal. Each receiver location in the operator item is matched to the corresponding input gather; if no matching operator is found, the module can either issue a warning, pass the gather through unchanged, or substitute the nearest available operator.
The vertical geophone (Z) component gather to be deghosted. This must be a prestack seismic gather sorted by receiver location, with the same receiver positions that were used when computing the PZ operator. Typical input is a common-receiver gather or common-shot gather from OBS acquisition.
The PZ summation operator computed by the PZ - Calculate module. This item stores one filter per receiver location and carries information about the calculation method (Stack matching or FK analysis). Connect the output of PZ - Calculate directly to this input. The operator item must be computed before this module is run.
The acoustic velocity of the water column at the receiver depth, in m/s. This value is used only when the PZ operator was calculated with the FK analysis method, where it defines the water slowness cone in the frequency-wavenumber domain. FK components with apparent slowness exceeding that of water (evanescent waves) are excluded from the application. The parameter has no effect when the Stack matching method is used. The default value is 1500 m/s, which is appropriate for typical open-ocean conditions. Adjust this value to match the measured sound speed at the sea floor if available, as an incorrect value will cause improper masking of the FK cone and may degrade the deghosting result.
Controls which spectral components of the PZ filter are applied to the data.
Amplitude and phase (default) — applies the full complex filter, correcting both the amplitude spectrum and the phase of the output. This is the standard choice for full deghosting.
Amplitude only — retains only the magnitude spectrum of the filter and discards its phase. Use this option when you want amplitude balancing between receivers without altering the phase character of the data, for example as a QC step or when phase changes are handled separately.
Phase only — normalises the filter to unit amplitude at each frequency and applies only the phase correction. Use this when the amplitude response is already correct and only phase alignment between the P and Z components needs to be adjusted.
Specifies the action to take when the PZ operator item does not contain a filter for the receiver location of the current input gather.
Do not modify input (default) — passes the gather through to the output unchanged and continues processing. Use this when missing operators are expected for some receivers and you prefer to retain the original, unprocessed data for those gathers rather than halt the job.
Notify — reports an error and stops processing for the current gather. Use this during QC to identify which receiver locations have incomplete operator coverage.
Find nearest valid operator — substitutes the operator from the spatially closest receiver for which an operator exists and applies it to the current gather. This is useful when a small number of receivers lack operators due to data gaps, and the water depth and geology vary slowly enough that a neighbouring operator is a reasonable approximation.
Selects whether the module runs on the CPU or on a GPU accelerator. GPU execution can significantly reduce processing time for large datasets when a compatible graphics card is available.
Enables distribution of the workload across multiple processing nodes in a cluster environment. When active, gathers are split into chunks and sent to worker nodes for parallel execution.
Sets the minimum number of gathers sent to each worker node per distributed execution chunk. Larger values reduce communication overhead; smaller values allow finer load balancing when gather processing times vary.
When enabled, caps the number of CPU threads used per worker node during distributed execution. Use this to prevent the module from monopolising node resources when other jobs share the same cluster.
An optional text label appended to the distributed job name. Use this to distinguish multiple simultaneous runs of this module in the cluster job queue.
When enabled, allows manual assignment of this job to specific CPU cores or NUMA nodes via the Affinity parameter. Useful for performance tuning on systems with non-uniform memory access architectures.
Specifies the CPU core or NUMA node mask to use when Set custom affinity is enabled. Leave at the default unless directed by a system administrator for performance optimisation.
Controls the number of CPU threads used for parallel processing within a single node. Increasing this value speeds up processing on multi-core workstations. The optimal value is typically equal to the number of physical cores available.
When enabled, this module is bypassed and input data is passed through to the output without modification. Use this to temporarily disable PZ application during testing without removing the module from the processing flow.
The deghosted vertical geophone gather after application of the PZ operator. The output has the same receiver geometry as the input but with the receiver ghost reflection attenuated. If the data and operator had differing sample rates, the output is resampled back to the original input sample rate and length before being passed downstream.