Full Waveform Inversion over the Valemon and Kvitebjørn Area in the Norwegian North Sea

We present a case study on Full Waveform Inversion (FWI) velocity model building from the Valemon and Kvitebj0rn fields in the Norwegian part of the North Sea. The area has a strong shallow seismic anomaly, causing pull-down at deeper reflectors. Previous attempts at including the anomaly in velocity models have created a smooth velocity reduction in the area around the anomaly, not conforming to geology. We show that FWI produces a very localized low velocity anomaly that corrects for the observed imaging problems, conforms to geology and match predictions from rock physics for sediment velocities in the anomaly. We also show how we optimize well ties with FWI and anisotropy, and finally we discuss how we can use reflections to both increase the detail in the velocity model and estimate background velocity trends.