Zhou, Chaoguang (Petroleum Geo- Services) | Martínez, Jaime Ramos (Petroleum Geo- Services) | Lin, Sonny (Petroleum Geo- Services) | Jiao, Junru (Petroleum Geo- Services) | Dahl, Sverre Brandsberg (Petroleum Geo- Services)
Wide azimuth towed streamer surveys (WATS) have recently proven quite successful at improving illumination and attenuating multiple energy in difficult subsalt imaging environments. However, they present new challenges in terms of survey design, acquisition and processing methodology and operations. In particular, the sheer volume of data acquired requires pragmatic approaches to data processing. A 2007 deepwater Gulf of Mexico WATS survey of exploration scale (10,000 km2) illustrates these challenges and demonstrates the need for increased fold and cross-line offset.
The past couple of years have seen a tremendous increase in the acquisition of wide azimuth (WAZ) surveys that provide improved subsalt imaging. We have seen a step change improvement in image quality compared to conventional narrow azimuth (NAZ) surveys, even when using minimal processing and existing, conventional-survey velocity models. The improvement in image quality is taken to the next level when the wide and rich azimuth data are combined with other seismic and non-seismic measurements to build ever more highly constrained models, and then more accurately migrated with two-way wave-equation methods.