A 2.5D Method for Removal of Free-surface-related Seismic Events

We present a method for removal of free-surface related events in marine seismic data, specialized for cases where subsurface properties vary slowly in one direction (strike) and the survey is well sampled in the orthogonal (dip) direction. Under these assumptions of 2.5D subsurface and suitable acquisition geometry, it is possible to reduce the data sampling requirements and computational costs with respect to 3D multiple attenuation methods, and consequently, apply (2.5D) methods that are potentially more accurate than the standard (iterative) ones. We derive 2.5D versions of non-iterative multiple attenuation methods and illustrate their performance and data sampling requirements in an application to complex synthetic data, representative of a North Sea field.