Singular Value Decomposition (SVD)

Attenuation of strong marine noise

Singular value decomposition is a tool for the attenuation of strong marine noise, such as

  • crossflow noise recorded during vessel turns
  • excessive swell noise
  • noise from in-sea devices attached to streamers.

It targets specific frequencies and energy levels. The term originates in linear algebra, where it is a technique used when dealing with sets of equations or matrices that are singular or very close to being so.

Flexibility for users

Noisy traces are detected by calculating the energy of the trace in a user-specified window. The user can also specify the energy threshold above which traces are deemed noisy; traces below the threshold are untouched by the process. 

SVD enables the application of noise attenuation within specific, tapered time windows. Multiple passes—targeting different frequencies and energy levels—can therefore be run in a time-variant manner. Noise removal is carried out iteratively; the output after each application of filtering forms the input for the next iteration. 

Enablement of innovative full-azimuth acquisition techniques

SVD has proven to be a robust and useful technique in the presence of crossflow noise—a low-frequency, high-amplitude noise mode that results from the movement of water across the streamer. It can be caused by strong rip currents or the intentional towing of the streamer in a circular or nonlinear manner. SVD's ability to remove this noise makes it a key enabler of Coil Shooting single-vessel full-azimuth acquisition and Dual Coil Shooting multivessel full-azimuth acquisition. It is also a key enabler of the CLA continuous line acquisition method for increasing acquisition efficiency by recording data during turns or line changes.

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