DUG Insight User ManualDUG Insight LearningFrequently Asked Questions WellsLimiting correction to a radius around the well data

# Limiting correction to a radius around the well data

## Calculate a residual correction without any constraints applied

1. To calculate the residual correction:
1. Use Create horizon from well markers to create a sparse horizon of your well marker to be tied.
2. Use Regrid to resample the sparse marker horizon to a regular grid at your final grid spacing eg 50m
3. Use Horizon maths to subtract the sparse horizon from the seismic horizon, the formula is h1-h2.
4. Use Interpolate/extrapolate to fill the entire area with the residual correction.

## Calculate a template defined by a radius from a well

1. To calculate the template:
1. Use Horizon maths to modify the regridded (sparse) horizon marker horizon to value 1. The formula is h1/h1.
2. Use Create constant horizon to create a horizon value 0 across the area of your final horizon. Use an X/Y spacing similar to or less than your final grid spacing e.g. 50m.
3. Use Horizon maths to merge the 2 horizons above together. The formula is merge (h1, h2), ensure the well marker horizon is listed first, h1. 1. Use Smooth to create non zero values around the well locations defined by a smoothing radius of your choice e.g. 1500m. If this takes a very long time, consider changing your grid increment in the previous steps.

Note: Create a new horizon each time if you want an audit trail, otherwise replace to update the template and reduce horizons generated. 1. Use Horizon maths to cut out the nonzero values. The formula if (h1>0, Nan, h1) should be used. 1. Use Horizon maths to merge the 0 template with holes together with the marker horizon value 1. The formula is merge (h1, h2), ensure the well marker horizon is first, h1.
2. Use interpolate/extrapolate on the merged horizon to create a smooth transition from value 0 away from the wells to value 1 at the well locations. Make sure the interpolated distance is larger than the radius used during smoothing eg 2000m
3. QC the template horizon in the Map View. 1. To apply the template to the residual correction, use Horizon maths to multiply the residual correction from part 1 with the template from part 2. The formula is h1*h2.
1. To apply the adjusted residual correction to the depth map, use Horizon maths to subtract the adjusted residual correction map from the seismic depth map. The formula is h1 - h2.
2. QC work in an arbline that passes through marker location.