The impact of multifocusing in the processing of land 3D seismic data in a fold and thrust belt setting: Ranquil Norte Block, Neuquén Basin, Argentina

Abstract

A total of 270 km2 of 3D seismic data was acquired in the southeast corner of the Ranquil Norte Block in the north of the fold and thrust belt area of the Neuquén Basin, west of Argentina. The survey was acquired in an area with hard topography, disturbing anthropomorphic conditions, and very complex subsurface geology. All of these situations negatively contributed to the signal-to-noise ratio of the resulting data. Therefore, and considering a structural target only, the main objective of the seismic processing sequence was the mitigation of the impact of such geologic and anthropomorphic noise on the data. Initially, a tailored processing sequence was performed, including noise suppression in the cross-spread domain. This first processing approach included Kirchhoff prestack time migration, structural seismic interpretation, velocity modeling, tomography, and Kirchhoff prestack depth migration. Given that multifocusing can deliver high-resolution subsurface images in areas with similar challenging conditions, this processing technique was then included in the processing workflow. Naturally, this second approach necessarily involved a reinterpretation of the structural model, a rebuilding of the velocity model, and a new tomographic computation. A significant improvement of the results was achieved in this manner.