TGS, Viridien commence Laconia Phase III OBN survey in the Gulf

Viridien and partner TGS have started Laconia Phase III to extend extra-long-offset-low-frequency full-azimuth sparse ocean-bottom node (OBN) data coverage in the Paleogene trend in the US Gulf of Mexico.

Phases I and II of its Laconia 3D OBN multi-client seismic program launched July 2024.

Supported by industry funding, Laconia Phase III covers about 150 Outer Continental Shelf blocks in the Keathley Canyon protraction areas. Phase III will be acquired by TGS and imaged by Viridien to target prospective but difficult-to-image subsalt reservoirs.

Acquisition started in May of this year, and initial products are scheduled for delivery in first-quarter 2026.

The program will utilize TGS’ ZXPLR nodes and the Sercel Tuned Pulse Source (TPS). TPS is a low-frequency broadband marine seismic source that is designed to enhance geophysical imaging clarity by improving low-frequency, deep penetrating sound energy.

The map shows the location of Phases I, II and III of Viridien’s Laconia 3D OBN survey.

Laconia Phase III seismic. — The seismic image highlights Laconia data in the Garden Banks area of the US Gulf. A legacy full-azimuth streamer 15-Hz RTM image is overlaid with 6-Hz streamer FWI velocity (top), and a Laconia Phase I long-offset low-frequency sparse OBN “early-out” 5-Hz FWI image is overlaid with corresponding velocity (bottom). Viridien says the early-out image demonstrates significantly improved imaging of the salt and the deep basin architecture, including potential subsalt reservoir targets in the Paleogene trend. The seismic sections intersect the Sparta discovery and the Kingsholm prospect (a dry well with oil shows).

The Laconia Phase III survey will also utilize Viridien’s elastic full-waveform inversion and reverse time migration imaging technologies to deliver seismic data to support both exploration and development activities.

"Outstanding early-out results from Laconia Phase I clearly demonstrate the power of Viridien’s industry-leading elastic full-waveform inversion imaging technology for setting new benchmarks for subsalt imaging and reservoir delineation," Viridien stated in its June 19 news release.

"The combination of very-long-offset OBN and the low-frequency Sercel Tuned Pulse Source (TPS) provides significantly deeper diving-wave penetration for E-FWI to resolve the complex salt geometries and sediments, producing a step change in subsalt imaging and highlighting exploration opportunities in the Paleogene trend with greater certainty."

Fast-track data from Laconia Phase I is available, and fast-track data from Laconia Phase II is scheduled for August.