Ocean bottom acquisition typically records data using both hydrophones and 3-component geophones. This allows recording of the full elastic wavefield and its separation into up-going and down-going parts.
Wavefield separation is the basis for standard PZ summation. This can be used to attenuate all receiver-side down-going multiples. However, source-side multiples are up-going at the receiver and cannot be removed by this conventional approach.
Up-down deconvolution is an effective and automatic free-surface demultiple for ocean bottom data. It can remove all surface-related water column multiples, including source- and receiver-side multiples, from input PZ or PS data. This process also implicitly designatures the data.
|Input P data (top) and Vz data (bottom). Event U refers to an upgoing primary and event M1 refers to the first-order water-layer multiple.
||After separation into upgoing (top) and downgoing (bottom) wavefields||Results of conventional PZ summation (top) and up-down deconvolution (bottom). Note the much improved multiple attenuation of the M1 event.
Data courtesy of the European Commision funded HYDRATECH project EVK3-CT-2000-00043,
recorded offshore Norway at the headwall of the Storegga Slide.