Understanding the imaging challenges at the Frigg Gamma discovery

The Frigg Gamma and Frigg Delta are oil and gas discoveries offshore Norway with a reservoir in the Frigg Formation at approximately 2000 m depth. The overburden is characterized by a set of complex effects that result in strong deterioration of the seismic image over the Frigg Gamma structure, whereas the Frigg Delta structure is relatively well resolved. Several seismic acquisition and processing projects have attempted to improve the seismic imaging in the area, but so far not adequately resolved these problems. In this study, we describe the structural setting causes the seismic imaging challenges. We construct a set of synthetic velocity models from well data, and study the effects of seismic imaging algorithms and their sensitivity to the velocity models. We show a model with vertical chimney-like cemented zones which creates pull up in time and strong scattering that resemble the real data.