The Unique Seismic Processing and Imaging Experience with Fascinating Data from Onshore Trinidad

Onshore Trinidad is an extremely complex and intensely deformed basin with many unconformities. Surface seismic data from this area generally has a low signal to noise with significant surface statics issues associated with a very low velocity weathered surface layer. The acquired seismic data also contains significant aliased surface wave noise, especially in 3D surveys, and the resultant final images seldom contain reflection data above 25Hz. Both 2D and 3D data were processed simultaneously and information and learnings from each was used in combination to refine the images from both datasets. Great care was taken at the outset with near surface corrections and noise attenuation with consideration given to the fact that reflection signal may masquerade as noise in such an environment. Many well-known traditional algorithms did not perform well on this data, it took an iterative layer stripping approach, sometimes with one step forward and two steps backwards, to optimize the signal processing element of the imaging. Pre-stack time velocity updating used a wide range of percentage velocity pre-stack migrated sections. This required a lot of experience with attention to detail, allowing sufficient but not excessive velocity variation while constraining interval velocities and optimizing the final migrated image.