Advancing subsalt imaging in the US Gulf: Operational and technical innovations in seismic data acquisition from the Laconia sparse OBN program

Abstract The Laconia program marks a major advancement in the design and execution of long-offset, low-frequency (LOLF) ocean-bottom node (OBN) seismic acquisition programs for subsalt imaging in the U.S. Gulf. With more than 18,000 km² of source coverage and more than 8000 node locations, this multiphase program builds on recent breakthroughs in full-waveform inversion (FWI) methodologies, sparse OBN geometry, and new source technology. A low-frequency-rich source — the Sercel Tuned Pulse Source (TPS) — was used to deliver LOLF OBN data with offsets greater than 50 km and ultra-low-frequency signal down to 1 Hz in the Garden Banks and northern Keathley Canyon. These LOLF OBN data enable the application of FWI to address long-standing challenges in salt velocity model building and in imaging the Wilcox Paleogene play beneath the notoriously complex salt structures in this region. The use of 150-day endurance nodes and a large node inventory enabled acquisition of ultra-long offsets consistently across the entire survey, demonstrating the scalability of multiclient OBN for basin-scale projects. Real-time telemetry of down-sampled hydrophone data enabled early FWI testing, allowing interpreters to gain insights on 5 Hz acoustic OBN FWI volumes three months before the fast-track delivery. Results from early-out FWI demonstrate substantial improvements in imaging the complex subsalt structures by resolving the velocity of overburden allochthonous salt and mobile shales. The program was executed with exceptional health, safety, and environment performance. The Laconia program sets a new benchmark for cost-effective, high-impact seismic acquisition and imaging at basin scale, delivering geophysical and geological value in structurally complex offshore environments, reducing structural and depth uncertainty beneath salt, and de-risking future drilling decisions.