Improving shallow water MWD: Offshore Canada case study

Data from towed streamer surveys in shallow water depths are usually contaminated by different orders of seafloor reflections called water-layer-related multiples (WLRMs). The model-based water-layer demultiple (MWD) method effectively removes WLRMs. The initial development of 2D MWD was followed by a 3D implementation to better handle out-of-plane WLRMs. This 3D implementation was further improved by using a selective-input strategy to handle the inconsistency of the high-frequency multiple patterns between adjacent sail lines. We also used time-variant apertures based on multiple contribution gathers (MCGs) to include sufficient large apertures, avoid aliasing problems, and compensate for apex shifting. Using narrow azimuth towed streamer (NATS) data from the Hibernia field, we demonstrate the benefit of selective-input MWD with time-variant apertures for attenuating WLRMs in shallow water data.