1. CLARITAS SWELL NOISE ATTENUATION PROCESS
DUSWELL
CLARITAS SWELL NOISE ATTENUATION PROCESS

2. Introduction
This presentation demonstrates the effectiveness of DUSWELL in attenuating swell noise from marine seismic data.
The data examples are from the Hawke Bay 3D survey (HB3D), acquired offshore East Coast New Zealand in 1999 by Geco-Prakla. Sailline 1157p1_020 was identified as being acquired during moderate to heavy swell conditions.
Shots, Stacks and difference displays are used to show the effectiveness of the DUSWELL process on the example dataset.

3. Dataset
Supplied data consisted of 1440 fold shot gathers, acquired with 2 guns and 6 streamers.
Additional processing applied pre swell noise attenuation:-
Spherical Divergence : T squared correction.
Anti-Alias filter – 2-4Hz Hz.
Resample to 4ms.
Assign Offsets to headers

4. Slide 1 - Raw Shot

5. Slide 3 – After DUSWELL

6. Slide 2 – Difference

7. Slide 4 – Stack – No DUSWELL

8. Slide 5 – After DUSWELL

9. Slide 6 – After 2nd PASS OF DUSWELL on common channels

10. Comments
For this dataset a single pass of DUSWELL was effective in attenuating the swell noise present on the seismic data.
DUSWELL when required can be applied in multiple passes and in different domains so can be effectively optimised for your particular datasets.

11. DUSWELL Information
The advantage that DUSWELL has over current techniques/methodologies available in Claritas are:-
Less damaging to the signal especially where the swell noise is broad bandwidth ie above 10Hz.
DUSWELL has the capability to reconstruct frequency bands which it attenuates.
DUSWELL can be iterated to target swell noise more effectively.
Can be run within a Claritas MPISTART/MPIEND loop and is therefore cluster capable.