Description

MF Params to Tomo Params (Common Offset) converts MultiFocusing parameter datasets into tomography parameter files suitable for stereo tomography velocity model building. The module scans the MultiFocusing parameter storage for locally coherent events at each common-offset class, extracts their travel times, source and receiver slopes, and other attributes, then exports them in the format required by the Stereo tomography solver. The user can interactively pick additional events on the displayed stack or semblance panels, apply horizon constraints, and control quality thresholds before creating the final tomo output files.

Input data

Storage file

The MultiFocusing parameter database file (.kdb) containing the pre-computed MF parameters for all common-offset classes. This file is produced by a preceding MultiFocusing parameter extraction step.

GMFPickingItem

The 3D picking item that stores manual and automatic horizon picks used to guide the tomo parameter extraction. Connect from the corresponding MF parameter or horizon picking module.

Parameters

Image creation parameters

Common component that controls how the inline stack and semblance images are constructed for display and interactive picking. These settings are shared with the MF image creation workflow.

Current offset for edition

The current common-offset class (m) being displayed and edited in the pick panel. Default: 1000 m. Change this value to navigate between offset classes and verify or correct the event picks for each offset band.

Current horizons

Index of the horizon layer currently selected for interactive editing. The list is populated from the horizons imported or picked in this module.

Datum

Reference datum elevation (m) used when converting horizon times to depths during tomo file creation. Default: 0 m.

Time from

Start time (s) of the data window displayed and processed. Default: -1 s (use full record length). Set to restrict extraction to a specific time interval.

Time to

End time (s) of the data window. Default: -1 s (use full record length).

Bin from

First CMP bin index of the data range to process. Default: -1 (process all bins). Set to restrict extraction to a portion of the line.

Bin to

Last CMP bin index of the data range to process. Default: -1 (process all bins).

Calc mode

Controls the computation speed versus accuracy trade-off during tomo parameter extraction. Default: Fast. Fast uses an optimised pipeline for quick results suitable for initial tests; Long applies more rigorous slope estimation for higher-quality tomo points.

Trace Aperture(N)

Half-aperture in number of traces used for local slope estimation around each event. Default: 10 traces. Minimum: 1. A larger aperture provides a more stable slope estimate but can smooth out lateral variations in dip.

Sample Aperture(N)

Half-aperture in number of time samples used in the local coherence estimation. Default: 10 samples. Minimum: 1.

Angle Aperture(Degree ZO)

Maximum dip angle (degrees) of the zero-offset ray allowed when extracting coherent events. Default: 15 degrees. Range: 1–90 degrees. Events with steeper zero-offset slopes are rejected as noise.

Sembalance Treshold

Minimum semblance value an event must achieve to be accepted as a valid tomo data point. Default: 0.05. Minimum: 0. Increase this threshold to accept only high-coherence events and reduce noise in the tomo dataset, at the cost of fewer data points. Decrease if the survey has low fold and few events pass the threshold.

Amplitude Treshold

Minimum normalised amplitude an event must have to be accepted as a tomo data point. Default: 0.005. Events with amplitude below this threshold (relative to the local trace maximum) are discarded as noise.

MIN_CEE

Minimum CRE (Common Reflection Element) coherence estimate required to retain an event. Default: 10000. This internal quality metric from the MultiFocusing analysis filters out events with poor CRE coherence.

CRE_CEE_FACTOR

Scaling factor applied to the CRE coherence estimate before comparing with MIN_CEE. Default: 0.1. Adjust to calibrate the relative sensitivity of the CRE quality filter.

Output Pick's File name

Path and file name for the output tomo correlation file (.corr). This file stores the extracted tomo data points and is used as input to the Stereo tomography solver.

Using types

Type of offset data used for tomo extraction. Default: CO. Options: CO — common-offset events only; ZO — zero-offset events only; ZO_CO — both zero-offset and common-offset events combined.

Calc Offsets

Container grouping offset range settings used to define the common-offset classes for extraction.

Calculated offsets

When enabled, the offset classes are computed automatically from OffsetFrom, Offset To, and Offset increment. When disabled, offset classes are read directly from the storage file.

OffsetFrom

Minimum source-receiver offset (m) of the first class to extract.

Offset To

Maximum source-receiver offset (m) of the last class. Default: 2000 m.

Offset increment

Offset step (m) between successive common-offset classes. Default: 1000 m.

Import horizons from ASCII params

Container grouping settings for importing horizon constraints from ASCII files via the Import horizon from ASCII custom action.

Location

Specifies whether the horizon times in the ASCII file are referenced to the processing Datum or to Topography. Default: Datum.

Datum

Reference datum elevation (m) used when Location is Datum. Default: 0 m.

Time measure

Time unit in the ASCII horizon file. Default: Milliseconds. Select Seconds when appropriate.

Manual picking params

Container grouping parameters that govern the manual horizon picking tool in the interactive stack display.

Manual picking window

Time radius (s) around the cursor position searched for the pick magnet snap. Default: 0.020 s. Minimum: 0.004 s. The magnet snaps the pick to the closest amplitude extremum within this window.

Pick type

Polarity of the amplitude extremum sought by the pick magnet. Default: Positive phase. Select Negative phase when picking on troughs.

Threshold

Minimum amplitude of the event for the magnet to snap to it. Default: 2.5. Increase to snap only to strong events; decrease on low-amplitude data.

Magnet type

Strategy for selecting the snap target. Default: Nearest — snaps to the nearest amplitude peak within the window; Max energy — snaps to the highest-amplitude peak within the window.