Optimising 4D Seismic with Evolving Technology over 20 Years of Reservoir Monitoring of the Gullfaks Field, North Sea

Seismic monitoring of the Gullfaks field has been in progress for over 20 years. Over that time changes in acquisition equipment and planning have led to improved 4D repeatability. In addition, upgrades in processing and imaging technology such as designature and demultiple have reduced 4D noise and consequently given us higher confidence in the interpretability of 4D signal. A monitor survey was acquired in 2016 with a multi-component streamer solution and thus led to a 4D time-lapse processing project including older vintage surveys. This paper summarises the various changes in acquisition over the years and shows that continuous improvement in acquisition design alongside backward compatibility, rather than strictly repeating acquisition parameters, pays off with better quality 4D results. Finally, some intermediate results from the latest processing show that even the best repeated surveys can benefit from reprocessing when compared with previous processing results.