VSP Free-Surface Multiple Imaging - A Detailed Case Study

We present a case study from the deepwater Gulf of Mexico, USA, where two orthogonal 2-D profiles are imaged using free-surface P-wave multiples recorded in a VSP survey. We compare VSP surface multiple imaging with primary VSP P-P imaging and 3-D seismic imaging. This demonstrates the expanded zone of illumination and the excellent image quality that can be obtained with the technique. However it also demonstrates the impact that 3-D subsurface geometry can have: we observe high quality imaging in the dip direction but significantly poorer imaging in the strike direction which we attribute to 3-D geometry and which is supported by ray-trace modelling studies.