Towards more effective and efficient through-gas-clouds time-lapse imaging at the Greater Ekofisk Area

For decades, the industry has been striving to obtain high-quality seismic images in Seismically Obscured Areas (SOAs) underneath gas clouds at the Greater Ekofisk Area (GEA). In the last couple of years, significant improvements have been achieved at both Eldfisk and Ekofisk fields through the adoption of modern acquisition and processing technologies. While standard 4D processing/analysis flows may work well for conventional problems, they are not sufficient to handle complex velocity settings such as those caused by shallow gas.In this paper we present recent improvements in 4D seismic imaging below shallow gas at the Eldfisk field through processing of repeat OBN datasets through Full Waveform Inversion (FWI), Reverse Time Migration (RTM) and Pseudo Offset Gather based Imaging (POGI).