Innovative workflows and a range of 3D gather preprocessing methods, including PZ summation, noise attenuation, and source directivity corrections, are fundamentally changing the way multicomponent data are processed in WesternGeco.
Full-azimuth OBC acquisition is now almost routine and can provide data gathers that can be processed as true 3D receivers in the so-called cross-spread domain. These gathers are being processed with 3D transforms that allow noise attenuation and azimuthal analysis and corrections that were not evident with previous narrow-azimuth inline geometries.
The gathers shown depict cross sections from raw 3D gathers of P and Z, with PZ summation applied, and final 3D noise attenuation.
In the 3D domain, we can apply random and coherent noise attenuation, source- and receiver-consistent azimuthal corrections, and several different PZ summation processes. The improvement in signal and long offsets allows not only improved imaging and velocity determination, but also further analysis of azimuthal effects. The same 3D gathers and processes are also improving the quality of PS data.
The images shown are from: "Clair 3D/4D – Demonstrating the Value in Reprocessing 3D Multicomponent Surveys”". Ashby, A., Aitchison, M., Dawson, A., (WesternGeco), Ibram, M., McGarrity, J., McKenzie, C., Fowler, S.,(BP, UK), 69th EAGE Technical Conference, July 2007, London.