Seismic Image Improvements after Correction for Errors in Obn Acquisition Parameters

Abstract

Summary Uncertainties in acquisition parameters of Ocean Bottom Node data impact image quality. In this study we consider spatial and temporal variations in water velocity and source positions as well node positions and clock drift. Our method inverts the direct arrival travel times using a joint linearized inversion for these parameters. Modelling shows that our approach is valid for travel times picks including offsets up-to an offset-to-depth ratio of 2.5. We find that spatial-temporal variations in the water velocity observed in the seismic data are similar to those observed by PIES. We also observe that during part of the survey the estimated water velocities are different between two simultaneous shooting vessel and from PIES data. Spatial variations in the water velocity have to be considered for surveys acquired by simultaneous shooting using multiple source vessels. We also show that our method can determine survey wide improvements to the position of each source array. We find that source positions are stable along straight saillines but variable source position corrections are found along trajectories with rapid change in the vessel heading. Application of the improved acquisition parameters results in observable differences in the shallow and observable deeper parts of the seismic image.