Description

An interactive tool for reconciling actual source and receiver positions against the theoretical, regularly-spaced acquisition grid (defined by line and station-point, or "SP", spacing) and correcting small positioning errors. Points that lie close enough to their nearest theoretical grid node are automatically snapped ("magnetized") onto that node; points that fall outside the tolerance are flagged as uncertain and left for you to inspect and reposition by hand on the map. Use it to clean up GPS/positioning noise in source and receiver geometry before binning, statics or further geometry-dependent processing, such as building cross-spread geometry.

Input data

Input trace headers

The trace header set whose source and receiver positions are checked and corrected. Use the "Init from input data" action to (re)build the working source and receiver grids from this input before reviewing or correcting geometry.

Bin grid

The project bin grid, used to determine the inline/crossline orientation of the survey when the theoretical source and receiver line grids are built from the input geometry.

Parameters

Source line step

The nominal spacing, in meters, between adjacent source lines in the planned acquisition grid. This defines the theoretical grid that actual source positions are compared and snapped against.

Default: 25 m, minimum 0.001 m. Set to match your survey's designed source line spacing.

Source SP step

The nominal spacing, in meters, between adjacent source station points (SPs) along a source line in the planned acquisition grid.

Default: 25 m, minimum 0.001 m. Set to match your survey's designed source station interval.

Receiver line step

The nominal spacing, in meters, between adjacent receiver lines in the planned acquisition grid.

Default: 25 m, minimum 0.001 m. Set to match your survey's designed receiver line spacing.

Receiver SP step

The nominal spacing, in meters, between adjacent receiver station points (SPs) along a receiver line in the planned acquisition grid.

Default: 25 m, minimum 0.001 m. Set to match your survey's designed receiver station interval.

Automatic source magnet tolerance

How close (as a fraction of the source line/SP step) an actual source position must be to its nearest theoretical grid node to be automatically snapped onto it. A source farther from its nearest node than this fraction is instead flagged as "uncertain" and highlighted on the map for manual review, rather than being auto-corrected. Raising the tolerance snaps more (and more distant) points automatically; lowering it is more conservative and flags more points for manual review.

Default: 0.4 (40% of the line/SP step). Allowed range 0 to 0.5. Reduce it if real, larger position offsets are being incorrectly auto-snapped; increase it to auto-correct more of the routine positioning noise and reduce the number of points needing manual review.

Automatic receiver magnet tolerance

The same auto-snap tolerance as Automatic source magnet tolerance, applied to receiver positions against the receiver line/SP grid instead of the source grid.

Default: 0.4 (40% of the line/SP step). Allowed range 0 to 0.5.

Output data

Output trace headers

The trace headers with corrected source and receiver line/SP positions applied (from automatic snapping and any manual corrections made on the map). Additional header fields are added recording the original source and receiver line/SP values, the corrected source and receiver X/Y coordinates, and flags marking which sources and receivers remain uncertain, so the corrections can be audited.

Grid item

The regular source and receiver line/SP acquisition grids built and corrected by this module. This output can be passed to other geometry modules, such as Create cross-spread geometry, that need the acquisition grid definition.

References

Cordsen, A., Galbraith, M. and Peirce, J., 2000, Planning Land 3-D Seismic Surveys: Society of Exploration Geophysicists.