The Foinaven-Schiehallion-Loyal area, located west of Shetlands on the UK Continental Shelf, has provided significant oil production for BP (operator) and its partners Shell (Schiehallion/Loyal), Marathon (Foinaven/East Foinaven), OMV (Schiehallion) and Faroe Petroleum (East Foinaven). 4D seismic has been successfully used in this region for infill drilling and reservoir management decision-making since the late 1990s. With a new 4D monitor survey acquired approximately every two years, the total number of vintages now stands at 10. The very earliest monitor surveys were acquired without 4D specification, but all later acquisitions were designed for 4D. The latest monitor survey from 2013 incorporates broadband acquisition technology and can serve as a baseline for future acquisitions. This paper shows how recent improvements in seismic time-lapse processing enhance the quality of the 4D seismic compared to the previous processing between 2008 and 2011 (Campbell et al., 2011): The 4D background noise is reduced, giving us a better stand-out of the 4D signal. Importantly, legacy data acquired before the advent of dedicated 4D acquisitions can also be significantly improved with new processing methods. A combination of incremental changes to the 4D processing sequence, new 4D algorithms such as 4D demultiple, and careful QC and developments from the continuous technology collaboration gives us increased confidence in the 4D interpretation and satisfies the needs of the reservoir management team.

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