Modeling the seismic wavefield of moving marine vibrator source

Abstract

Marine vibrators are an emerging alternative to conventional air guns in ocean-bottom acquisition due to their ability to generate low-frequency waves and limited adverse impact on marine wildlife. However, using marine vibrators introduces challenges not found in conventional air-gun-based acquisition where receivers are placed on the ocean bottom, including handling the phenomena associated with the Doppler effect and time-dependent source-receiver offsets due to the source motion. Standard seismic data processing solutions assume stationary sources and receivers for the duration of any seismic experiment (e.g., a shot); however, accurately accounting for source motion effects in processing is critical for optimal subsurface imaging. To address these challenges, we develop a finite-difference approach for modeling the full acoustic wavefield in a generalized coordinate system that tracks a moving source. Synthetic examples demonstrate that this technique accurately and stably models high-velocity moving sources and accurately accounts for the wavefield distortion predicted by the Doppler effect. This approach is not limited to modeling wavefield propagation for a moving source and can be used to develop advanced imaging and inversion techniques (e.g., reverse time migration and full waveform inversion) for data acquired using marine vibrators. In addition, the developed approach is not only limited to modeling mobile sources but also can model conventional towed-streamer data.