Improving 3D Water Column Seismic Imaging Using the Common Reflection Surface Method

© 2020 Elsevier B.V. Water column processing has gained attention in recent years since a seismic model of a water column could assist marine data processors to correctly image the sub-seafloor geology, which is the target of primary interest. In addition to seismic processing, water column imaging has gained interest in the physical oceanography community for improved study of oceanographic processes. However, seismic water column processing is challenging since the internal reflections of the ocean are inherently weak and are often masked by noise. In this work, we adopt the common reflection surface stack technique in order to improve the imaging of ocean water layers. The common reflection surface stack is a robust data preconditioning and stacking technique in seismic processing that relies on the kinematic wavefront attributes of seismic waves. The method is applied to a multichannel 3D data set collected for oil and gas exploration in the deep-water Gulf of Mexico. The method greatly improves inline sections but does not significantly enhance crosslines and horizontal slices, which are more sensitive to both the acquisition geometry and the temporal variability of ocean water masses

Temporal and Spatial Variations In Three-Dimensional Seismic Oceanography

Seismic oceanography is a new cross-discipline between geophysics and oceanography that uses seismic reflection data to image and study the oceanic water column. Previous work on seismic oceanography was largely limited to two-dimensional (2D) seismic data and methods. Here we explore and quantify temporal and spatial variations in three-dimensional (3D) seismic oceanography to address whether 3D seismic imaging is meaningful in all directions and how one can take advantage of the variations. From a 3D multichannel seismic survey acquired for oil and gas exploration in the Gulf of Mexico over a 6-month period, a 3D oceanic seismic volume was derived. The 3D seismic images exhibit both temporal and spatial variations of the ocean, and theoretical and data analyses were used to quantify their contribution. Our results suggest that temporal variation is more prominent in the crossline direction than in the inline direction, causing discontinuities in crossline images. However, a series of 3D inline images can be seen as snapshots of the water column at different times, capturing temporal variation of thermohaline structures induced by ocean dynamics. Our findings suggest the potential uses of marine 3D seismic data in studying time-evolving mesoscale ocean dynamics