Recursive Imaging with Multiply-Scattered Waves Using Partial Image Regularization: A North Sea Case Study

Abstract

As more resources are directed toward reverse-time migration an accurate velocity model, including strong reflectors, is necessary to form a clear image of the subsurface. This is of particular importance in the vicinity of salt, where singly-scattered waves are often not ideal for imaging the salt flanks. This has led to interest in processing doubly-scattered waves (also called duplex or prismatic waves) for imaging salt flanks and thus improving the location of salt boundaries in a velocity model. We present a case study in which we use doubly-scattered waves in a two-pass one-way method to image salt flanks in a North Sea data set. By working in the one-way framework we are able to separately construct images with singly, doubly, and triply scattered waves. We illustrate a multi-step imaging process that includes multiply-scattered waves by using an imaged reflector to fix one (or more) of the scattering points, allowing for multiply-scattered energy from several reflectors, potentially with poor continuity, to be included without picking each reflector individually. With this method we are able to image the flank of a North Sea salt body.