Full Waveform Inversion (FWI) uses every aspect of the recorded seismic wavefield to provide high-resolution earth models. CGG has demonstrated the benefits for many acquisition scenarios including ocean bottom, conventional streamer, BroadSeisTM variable-depth streamer and onshore. Algorithms such as Reverse Time Migration (RTM) can make full use of the detailed velocity models to produce clearer seismic images of the subsurface.
The topic of FWI is well represented in the technical schedule for EAGE 2013, with dedicated sessions covering theory, case studies and near-surface applications. Amongst these, CGG are authoring four papers, each involving a different variety of marine seismic.
The first paper (We-11-02) discusses the CGG StagSeisTM full-azimuth marine survey in the Gulf of Mexico. To determine the velocity structure of the complex overburden, FWI made full use of the ultra-long offsets (18km) and full azimuthal coverage out to 10km.
FWI applied to conventional narrow-azimuth towed streamer data from the Barents Sea is the topic of the second paper (We-11-06, co- authored with BG). The study is over the Samson Dome region, known for its geological and structural complexity.
The third paper (Th-07-01, co-authored with ConocoPhillips (Norge), discusses the results of FWI using multicomponent ocean bottom cable data recorded with the Ekofisk permanent monitoring system deploying Sercel OPTOWAVETM ocean-bottom channels.
Finally, the use of FWI with CGG BroadSeis data is described in the fourth paper (Th-08-10). FWI adapts naturally to the variable-depth streamer geometry and benefits from the improved low frequencies. Examples from the Central North Sea reveal detailed velocity features associated with shallow channels in the near-surface geology.
Away from the technical sessions, CGG will be making FWI presentations on its booth No. 530.
[mappress] Press Release, June 12, 2013