Seismic Processing Challenges Related to Leakage of Hydrocarbons from the Frigg Gamma Field

Leakage of oil and gas is associated with significant calcite cementation in the overburden of the Frigg Gamma Field. This cementation makes seismic imaging of the field with conventional streamer seismic extremely challenging. Different approaches are tested: Source-over-cable acquisition, undershooting by ultrafar offset seismic, high resolution site survey imaging, improved depth imaging with Full Waveform Inversion (FWI) velocity model, diffraction imaging, and PS processing of OBC data. Combined, these have given a better understanding of the leakage structures and it constrains the size of the leaking trap.