Practical multi-parameter FWI at the South Arne field

South Arne presents a velocity-model building challenge with large gas cloud obscuring underlying chalk reservoirs. Above the gas cloud is a complex near-surface with lateral velocity (Vp) variations. Additionally, a thin layer of strong anisotropy (peak epsilon around 23 %) occupies a 200-500 m interval in an otherwise isotropic overburden. The velocity model was updated with focus on reducing parameter cross-talk using 2-parameter Vp/epsilon joint FWI, then Vp/Q joint FWI. The FWI is run with combined OBN and towed-streamer input data, using a shot weighting strategy to balance the contributions to the gradient and global cost.