Abstract
The Independent Simultaneous Source (ISS) seismic acquisition in the southern Columbus Basin conducted by WesternGeco for BPTT is in the early stages of seismic processing. Early results are already revealing improved imaging and structural interpretations.
Improvements in imaging and depth conversion are compelling, largely the result of full azimuths, longer azimuths, higher fold, lower frequency content and P/Z recording. Because of these factors the resultant OBC data leads to improved velocity model building utilizing BP's Full Waveform Inversion, FWI, techniques.
In a field wide comparison done in the southern part of the basin the OBC image provided marked increases in the following over the heritage streamer data; Fault clarity, where reflector terminations and linkages are much clearer.Reflector continuity, especially in the deeper (greater than 12,000 ft. depths). This improvement seen throughout the dataset is most noticeable below shallow gas accumulations and in areas next to platforms previously only covered by lower fold data. Seismic sequences are also now more interpretable.Flat-spot detection where previous identification was unknown.Early results also point to improved spatial positioning of reflectors under shallow gas accumulations and, in the depth migrated volumes, the removal of the sag due to incorrect velocity fields.
This paper illustrates comparisons in the Columbus Basin between the new OBC data and heritage streamer data in support of the above claims of improved image and depth positioning.
Depth Velocity Model Building beyond Reflection Tomography, a case study, offshore Vietnam