Exploring Swell Noise Attenuation: A Route to Advanced Techniques
Harvex Geosolutions Limited
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Swell noise, a low-frequency disturbance caused by ocean waves, poses a significant challenge in marine seismic data. Its removal is crucial for accurate subsurface imaging and interpretation. Various methods have been developed to tackle this issue, each with its strengths.
Bandpass filtering has long been a reliable technique in seismic data processing, helping to attenuate unwanted noise and enhance the signal-to-noise ratio (S/N). It's particularly effective for many types of noise and has been a staple in the industry for good reason.
However, when dealing with swell noise, bandpass filtering has been found to face some challenges. Swell noise often overlaps with the frequency range of seismic signals and can have a broad, coherent frequency spectrum as seen in the figure. This overlap makes it tricky to completely separate the noise from the signal using traditional bandpass methods.
In the exploration of more targeted approaches for swell noise, the iterative FX prediction filtering method, as discussed by Schonewille, et al., (2008) has been discovered as an alternative and more effective approach. This method operates in the frequency-space (FX) domain and is promising for dealing specifically with incoherent noise like swell noise.
The process involves applying FX prediction filtering to the seismic data, replacing noisy trace segments with their filtered versions. It then detects remaining noisy segments based on their high amplitude relative to surrounding data and applies further filtering to these segments. This iterative process is repeated several times, progressively attenuating the swell noise.
While bandpass filtering remains a valuable tool in the seismic processing toolkit, the iterative FX prediction filtering approach might offer some advantages for swell noise attenuation. It is quite effective at reducing swell noise amplitude while potentially preserving more of the seismic signal integrity.
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What are your thoughts on this? Have you had experience with either method in dealing with swell noise? We'd love to hear about your experiences and insights!
Harvex Geosolutions Limited is in Partnership with Shearwater GeoServices to provide Marine Seismic Acquisition and Processing services to the Oil and Gas Industry.
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Geophysicist | MSc at University of Aberdeen
8 个月Great writeup. Noise attenuation generally is a crucial part of seismic processing. This is usually carried out at the initial stages of the processing sequence. As rightly put, bandpass filtering is not the most idle way to attenuate swell noise in seismic data as this has the potential of taking out signals as well. Fourier-transforming the data from the t-x (time-distance) domain to the F-K (frequency-wavenumber) domain enables seismic events to be differentiated by virtue of their velocity and dip. By specifying a pass zone, reject zone, and a taper zone, noise can effectively be filtered from the data. I look forward to seeing more advanced techniques to successfully attenuate swell noise in the industry ??