This technical report presents the application of Full Waveform Inversion (FWI) imaging in a towed streamer case study conducted in the Usan field, offshore Nigeria. The document outlines the advancements in 4D seismic data processing, emphasizing the shift towards FWI imaging over traditional methods. It discusses the methodology employed, including the use of both diving waves and reflections to derive an accurate velocity field, and the advantages of the proposed 4D FWI algorithm that jointly inverts baseline and monitor datasets. The report details the comparative analysis between parallel and joint 4D FWI schemes, highlighting the efficiency of the latter in reducing the number of iterations required for processing. Furthermore, it addresses the challenges faced in conventional 4D processing workflows and the improvements achieved through the integration of FWI imaging techniques. The findings contribute to the understanding of reservoir surveillance and the identification of drilling opportunities in complex geological settings.