Multicomponent OBC (4C) Time Imaging over Pamberi, Offshore Trinidad

Results from the P-P and P-Sv prestack time migration of a four-component (4C) OBC seismic swath test acquired in 2004 over the Pamberi area in Block LRL offshore Trinidad, are presented. A description of the processing applied to the multicomponent seismic data, through curved-ray anisotropic Kirchhoff prestack time migration for both the compressional P-wave and mode-converted PSv-wave, is provided. Mode-converted shear-wave data acquired from 4C surveys allow for imaging where conventional seismic data are perturbed due to the presence of shallow gas or fluid in the pore spaces of the rock. Furthermore, mode-converted shear waves propagate with a different raypath than that of the compressional wave, thereby providing an alternative illumination of the subsurface target. As both the P-wave and S-wave record independent measurements of the same subsurface, more reliable rock properties can be uniquely determined, allowing for improved reservoir characterization and lithology prediction. A conventional towed-streamer 3D was acquired over the Pamberi area in 2003, but failed to resolve adequately the target reflectors comprising the reservoir under the main growth fault. Therefore, the purpose of the 4C survey was to evaluate the potential of long-offset multicomponent technology for resolving stratigraphic interpretation in areas of complex challenging geology.