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Solving Water Column Statics with Seismic Oceanography
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 77th EAGE Conference and Exhibition 2015, Jun 2015, Volume 2015, p.1 - 5
Abstract
We present a method of compensating for variable water column velocity by using seismic oceanography to build a velocity model of the water column.
Water column statics have been a longstanding issue in the processing of deep-water 3D surveys and current methods all have significant limitations. Commonly, zero-offset traveltimes are picked for the seabed reflector and processed to detect discontinuities between saillines. Alternatively, seabed traveltimes may be picked at over a range of offsets in order to determine the average water column velocity. Both of these methods are problematic in areas with a highly rugose seabed.
We developed a processing sequence to image reflections in the water column itself, which are inherently low-dip and therefore not subject to significant dip-dependency of stacking velocity. The processing challenges were to remove low frequency noise and multiple energy from the previous shot. The picked velocities can be used to calculate water column statics which we show to successfully remove discontinuities between saillines in a 3D stack volume. We also produced images of the water column across a large 3D survey which may be of interest beyond exploration geophysics.