Change domain of horizon from time to depth (PSDM stage)
This module is designed to convert interpreted horizons from the time domain to the depth domain. Horizon data is typically provided by an interpretation team in a text format, consisting of columns for the X and Y coordinates, as well as the Z values representing the picked time values (t0) for the horizon.
Using the input velocity model, the module performs the conversion of the time-based horizon data into depth values. The resulting horizon (item) in depth can then be used in subsequent processes, such as the estimation of the anisotropic parameter Epsilon in the VTI Epsilon Estimation module. This conversion from time to depth is crucial for accurate subsurface modeling and allows for more detailed analysis of anisotropic properties in the subsurface.
This module is part of a larger sequence in the processing of seismic data within the depth domain, known as Pre Stack Depth Migration.
There is no parameters here (please, find input horizon files and velocity in the parameters tab).
Velocity import type { Gather, Files } - select type of input interval velocity model (depth domain): gather or SEGY file on a disk.
Input files velocity - if Files is selected: select SEGY file of input interval velocity model (depth domain).
Depth velocity - if Gather is selected: select SEGY file of input interval velocity model (depth domain).
Horizons type { Item, Files, Matrices } - select type of input horizon (time domain): item is a internal data type that can saved and imported from the g-Platform data base, file on a disk or matrix (this is type of map that can be created in Create interpolation matrix module).
Input files horizons - select SEGY file on a disk: input interval velocity model (depth domain).
Input time horizons - connect horizon Item data type from Load item module or from specific module that generates this type of data.
Input matrices - connect matrix from specific module that generates this type of data (Create interpolation matrix).
V0 - define velocity (m/s) in a low velocity zone (weathering zone).
Trace step to fit - module get this amount of traces for conversion from time to depth, i.e. chunk by chunk in accordance with geometry (which is read from velocity gather) recommendation is to keep it by default is 50 traces.
Import horizons from ASCII params - parameter for horizons file importing:
Location { Datum, Topography } - select the datum type on what level horizon is located: constant of elevations.
Datum - if Datum option is selected define a constant datum plane value in meters.
Scalar - if necessary, scalar coefficient that will be applied to time values.
Add constant shift time - if necessary add a constant shift in milliseconds to the horizon.
Add constant shift depth - if necessary add a constant shift in meters to the horizon.
Map interpolation - define interpolation method and parameters for horizon map creation from input grid (points item):
Interpolation type { Kriging, ABOS } - algorithms for map interpolation: Kriging, ABOS.
Kriging covariance { Spherical, Gaussian, Exponential } - - the covariance type refers to the mathematical model used to describe the spatial correlation between data points. This covariance model plays a crucial role in defining how the values at different locations are statistically related, which directly impacts the interpolation results.
Exponential - Suitable for data with rapidly decreasing spatial correlation. Correlation diminishes exponentially with distance but never truly reaches zero.
Spherical - A commonly used covariance type that assumes the spatial correlation increases up to a certain distance (called the range), beyond which points are uncorrelated. The correlation gradually decreases as the distance approaches the range.
Gaussian - Represents a smooth, gradual decrease in correlation, often used for very continuous data.
Kriging range - parameter of the variogram or covariance model that defines the maximum distance over which spatial correlation exists between data points. Beyond the range, the values at different locations are considered uncorrelated or independent.
Kriging max points - refers to the number of nearby data points used to estimate the value at an unknown location during the interpolation process. This parameter controls how many known values in the vicinity of the target point are included in the kriging calculation.
Interpolation step X - step in meters for the interpolation along X axes.
Interpolation step Y - step in meters for the interpolation along Y axes.
Number of threads - limit number of threads on main machine.
Skip - switch-off this module (do not use this module in the workflow).
Output depth horizons - horizon item in depth domain that can be used in VTI epsilon estimation.
Output time horizons - horizon item in time domain.
Example of the workflow: read depth velocity model as gather and horizon picking from ASCII file, then convert horizon time domain t0 to depth domain h0:
Resulting horizon in depth domain can be used in the VTI epsilon estimation module as input data:
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