Focused Gaussian Beams for Seismic Imaging

The application of focused Gaussian beams is investigated for the seismic imaging of common-shot reflection data. The focusing of Gaussian beams away from the source and receiver surface adds flexibility to beam imaging algorithms allowing for the narrowest portions of the beams to occur at the depth of a specific target structure. This minimizes the number of beams required to form an image at the target depth. The beam fronts at the beam-waists are also planar leading to more stable beam summations for imaging. To match with the surface data, a quadratic phase correction is required for the local slant-stacks of the data. Also, to use the same local slant stacks of the data for the different imaging depths, only a single focusing depth can be specified. Imaging using focused Gaussian beams is tested using a single shot gather for a model with 5 scatterers at different depths. The approach is then tested for a single shot gather from the Sigsbee2A model. In all cases, the beams can be focused to a particular target depth, but proper imaging still results for other depths as well.