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Uphole velocity model builds a 3D near-surface interval velocity model from uphole survey data. The module imports depth-versus-traveltime measurements from uphole wells, fits a regression curve (polynomial or piecewise linear) to the measured traveltime–depth pairs at each well, and then interpolates the resulting velocity function onto a regular 3D grid covering the survey area. The output is a depth-domain velocity gather suitable for static correction and depth-velocity model input workflows.
Uphole surveys measure the one-way traveltime from a downhole explosive source to surface geophones at known depths, providing a direct measurement of near-surface interval velocity. This module processes those measurements interactively — wells can be imported and cleared, individual depth slices can be computed, and the full 3D model can be built for use in refraction statics or depth migration velocity model initialisation.
Trace header vector providing the spatial coordinate information (X, Y, elevation) used to establish the survey grid onto which the well-based velocity model is interpolated.
Cell size (m) of the output velocity model grid in the X (inline) direction. Default: 50 m. Set to the desired lateral resolution of the near-surface model; typically this matches the bin spacing of the seismic survey.
Cell size (m) of the output grid in the Y (crossline) direction. Default: 50 m.
Vertical sample interval (m) of the output velocity model. Default: 1 m. Set to the vertical sampling needed to resolve thin near-surface layers.
Maximum depth (m) of the output velocity model. Default: 100 m. Set to the maximum uphole depth in your survey or to the base of the near-surface zone that needs to be modelled.
Lower velocity clipping limit (m/s) applied to the output model. Default: 0 m/s. Set to a physically realistic minimum near-surface velocity (e.g., 300 m/s for unconsolidated sediments) to prevent unphysical values.
Upper velocity clipping limit (m/s). Default: 10000 m/s. Reduce to the maximum expected near-surface velocity for your geology to prevent outlier regression results from producing unrealistic high velocities.
When enabled, the output grid geometry is defined manually using the Grid definition container rather than being derived automatically from the Input trace headers. Default: off. Enable when you need the uphole model to cover a specific geographic area that differs from the current survey footprint.
Container for manual grid geometry parameters. Active when Define grid manually is enabled.
X coordinate (m) of the origin corner of the manually defined grid. Default: 0 m.
Y coordinate (m) of the origin corner of the manually defined grid. Default: 0 m.
Compass azimuth (degrees) of the inline direction for the manually defined grid. Set to match the survey inline orientation.
Total length (m) of the manually defined grid in the inline direction. Default: 10000 m.
Total length (m) of the manually defined grid in the crossline direction. Default: 10000 m.
Angle (degrees) between the inline and crossline axes of the manually defined grid. Default: 90° (orthogonal grid). Change only for oblique survey geometries.
Container controlling how the traveltime–depth relationship is fit to the uphole measurements at each well.
Curve type fitted to the measured depth–traveltime data at each uphole well. Default: Polynomial. Polynomial fits a single polynomial of degree Regression power; 1-Linear, 2-Linear, and 3-Linear fit piecewise linear functions with 1, 2, or 3 segments, which can better represent abrupt velocity boundaries at the base of the weathering zone.
When enabled, the origin point (0 m depth, 0 ms traveltime) is included as an additional constraint in the regression. Default: off. Enable to force the regression curve to pass through the surface, which is physically correct if the first geophone is at zero depth.
Search radius (m) around a grid point within which uphole wells are included when computing a locally weighted regression. Default: 1000 m. Increase when the uphole well spacing is large and each regression must draw on more distant wells.
Degree of the polynomial used when Regression method is Polynomial. Default: 2. A degree-2 polynomial is a simple parabola that fits smooth gradational velocity increases; increase to degree 3 or 4 for more complex near-surface velocity structures.
Number of depth slices used to smooth the velocity model vertically. Default: 4 slices. Increase to suppress depth-sampling artefacts in the output model.
When enabled (default), a lateral smoothing filter is applied to the velocity model after building it from the well regressions. This reduces abrupt lateral changes between sparse wells. Disable if the raw interpolation is already smooth enough.
When enabled, the module computes only the single depth slice specified by Current slice depth instead of the full 3D model. Default: off. Use for fast interactive QC of the velocity at a specific depth before committing to a full model build.
Depth (m) of the single slice to compute when Calc only current slice is enabled. Default: 5 m.
Selects the processing device. CPU is standard for this module.
Configuration for distributed (cluster) execution.
Minimum number of gathers sent per work chunk during distributed execution.
When enabled, restricts CPU thread count per cluster node to the value in Number of threads.
Optional text appended to the distributed job name.
When enabled, applies the CPU affinity mask specified in Affinity.
CPU affinity mask applied when Set custom affinity is enabled.
Maximum number of CPU threads used during execution.
When enabled, this module is bypassed and data passes through unchanged.
The output near-surface interval velocity model as a velocity-domain gather, with the velocity axis sampled at depth intervals defined by Delta Z up to Max depth. Connect to downstream statics correction or depth migration modules that require a near-surface velocity model.
Opens a file browser to import uphole well data files (depth–traveltime tables) into the module. Multiple wells can be imported and are displayed on the location map in the Graphics panel.
Removes all imported uphole wells from the module. Use before re-importing a corrected set of well files.