Efficient Depth Model Building Using FWI Early in the Workflow: a Case Study from the Norwegian Sea

The Skarv field in the Norwegian Sea lies in the structurally complex area of the Nordland Ridge. Velocity complexity in the near surface has proved challenging for model building in previous studies and this complexity is targeted in the current study via full-waveform inversion (FWI). FWI is a valuable depth model building tool that can provide accurate, high-resolution velocity models of shallow to intermediate depths. In this study, FWI was employed early in the model building workflow, providing rapid updates of a simple starting model. This case study demonstrates the efficiencies that can be gained by utilizing FWI at these early stages, by leveraging the strengths of FWI in updating shallow structure which can prove challenging for reflection tomography. In addition, further efficiency was gained by early FWI work in parallel to the initial model building stage of the workflow which can quickly highlight areas of the initial model that require further investigation. The results of this study provide an accurate, robust, and high-resolution model of the shallow to intermediate model depths that give a solid foundation for further model building via reflection tomography.