Improved marine 4D repeatability using an automated vessel, source and receiver positioning system

An automated and integrated, vessel, source, and receiver control system has been developed to improve the accuracy and repeatability of 4D surveys. The control system replaces the need for operator intervention with automated updates to all active seismic elements – vessel, source, and streamer steering devices. These updates are derived from the real time integration of positioning information from in-sea equipment, environmental information, and the survey plan. Results from field trials and commercial surveys have shown that the new system leads to a step change in the accuracy of source repeatability (typically 2.5 m repeat accuracy for 95% of shotpoints) and also improved repeat receiver positions. Although streamer steering can apply up to 3° of correction against natural feathering, we show that as long as currents have a tidal-driven predictability, ± 9° of natural feather can be accommodated through careful survey planning.