[Users] Swell filter in OpendTect

[Arnaud Huck]

Dear OpendTect users,

The swell filter (http://en.wikipedia.org/wiki/Swell_filter) can be
applied in OpendTect base using the following steps:

- Track your seabed reflector using the horizon tracker. Optionally
import this horizon from an external source (first break picking
package...).
- Filter the horizon using the embedded filters in the right-click menu
of the horizon. The filter settings (median, average, stepout) will be
the main parameters of this filter. Save the output as a new horizon.
- Calculate the static shifts by computing the isopach between the
filtered and tracked horizons: Use the function "Calculate isopach" in
the right-click menu of the filtered horizon. Compute the isopach to the
original horizon, the output will be displayed as a grid on the filtered
horizon.
- Right-click on the isopach attribute in the tree and use the option
"Save attribute".
- Open the attribute engine (Processing --> Attributes)
- Create an attribute called "difference" that will read this grid:
attribute type "Horizon", select your input seismic cube, the filtered
horizon and output as "Select surface data" the isopach attribute.
- Create an attribute of type mathematics to convert the shifts from
seconds to milliseconds and invert the shifts: Formula x0*c0, select the
difference attribute as input, c0 = -1000. You can call this attribute
"difference in ms".
- Create an attribute of type "Delta resample" called "apply swell
filter". Inputs are your stored seismic volume and the "difference in
ms" attribute.
- Apply this attribute on a line to check the result. If your are
satisfied output the attribute "apply swell filter" to the entire volume
from Processing --> Create output.

Best regards,
Arnaud Huck.
Geoscientist.

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