Reverse time migration of mobile marine vibrator data

ABSTRACT Marine vibrators are viable alternatives to seismic air guns in ocean-bottom acquisition due to their less adverse impact on the environment, their ability to generate lower frequency content, and their suitability for simultaneous acquisition. However, mobile marine vibrators introduce a unique set of processing and imaging challenges for ocean-bottom acquisition, the main examples of which are the Doppler effect and the time-dependent source-receiver offsets, which are not features of conventional marine acquisitions. Standard seismic data processing and imaging techniques assume stationary sources and are not fully suitable for mobile marine vibrator data without modifications. Not accounting for source motion in seismic imaging introduces a phase change and a mispositioning of imaged structures. Further, ignoring source-motion effects in the imaging workflow may lead to the estimation of inaccurate migration velocity models or imply the use of incorrect migration velocity (e.g., in seismic-to-well ties). We develop a reverse time migration (RTM) approach that accounts for the source-motion effects and is capable of producing accurate subsurface images, closely matching stationary acquisition and imaging results. Synthetic examples show the ability of our method to construct accurate subsurface RTM images even for source velocities higher than those commonly used in typical marine acquisitions. Our approach is not limited to imaging mobile marine vibrator data in ocean-bottom acquisition but is also applicable to mobile streamer data using marine vibrators or seismic air-gun sources.