In the last two years the industry has seen a paradigm shift with the advent of Full waveform inversion (FWI) imaging in 3D seismic data processing projects. Fundamentally this is a fairly simple process as the image is merely a directional derivative of a velocity model, the resolution of which is largely controlled by the maximum frequency of the FWI and of course the subsurface properties. As FWI is an iterative least squares solution of the full wavefield, it has the ability to provide cleaner products over an extended coverage as it uses primaries and multiples. FWI imaging has also enabled turnaround time for projects to be significantly reduced.
Initially, there was some skepticism about the amplitude fidelity of such volumes, but through a series of examples, the industry has accepted the technique as either an alternative solution, or in some cases as the primary interpretative product. Despite the progress made, there are still very few published examples of using FWI imaging in 4D. In this paper we show the application of this technology to show a towed streamer example offshore Nigeria.
We will share examples of parallel 4D FWI (run FWI on each 3D and subtracting) versus a joint 4D FWI scheme, which produces equivalent results, but requires only half the number of total iterations per frequency relative to the parallel approach. We then compare the results of the 4D FWI with a conventional 4D processing workflow, discuss the advantages and disadvantages of each, and also highlight future considerations.
Read the full article here.