North Sea Renaissance: Exploring the Mid-North Sea High
Offshore exploration in the North Sea dates back to 1964 when the UK Continental Shelf Act came into force. Several gas discoveries were made, but exploration interest quickly declined towards 1968 due to low gas prices and therefore little commercial value. In 1969, Phillips Petroleum discovered Ekofisk with 6.4 Bbo in place. This triggered a surge of discoveries which up until now has made the North Sea one of the most prolific oil provinces in the world.
Clari-Fi Broadband Reprocessing
During the exploration history of the North Sea, a huge variety of seismic surveys has been acquired. However, by early 2000 few datasets existed which had been shot using long-offset streamers for deeper imaging, and no regionally consistent dataset had been acquired. In 2003 TGS therefore decided to start acquiring a multi-year super-regional south-west to north-east/north-west to south-east grid using long-offset streamers. The project was named North Sea Renaissance (NSR). By end of 2013, this huge NSR multi-year project had resulted in a super-regional grid with ~100,000 km of long-offset 2D seismic covering the entire North Sea.
One of the main objectives while acquiring the NSR grid was to ensure a regionally consistent long-offset 2D dataset. This was partially ensured by maintaining consistency in the acquisition parameters for the different vintages. However, some variations between them occurred due to each vintage being separately processed as they were acquired, as well as variations in processing sequences as TGS processing technology advanced.
In 2014, TGS therefore decided to fully reprocess the entire long-offset NSR grid into one seamless matched and merged Clari-Fi broadband dataset, using the latest TGS processing technologies.
Preparing for the Next UK Licensing Rounds
Exploration through the last decade in the expected 29th round area has focussed on pre-Zechstein targets. Leads and prospects have suffered significant uncertainties due to the poor imaging of the vintage data available. The Clari-Fi broadband dataset allows better definition both regionally and at prospect level, significantly reducing key uncertainties within a wider regional structural and stratigraphic framework. Utilization of gravity and magnetic data during processing highlighted the areas in the 29th Round that required more focussed processing effort in order to provide better imaging of deeper basins and sub-basins. Further integration of seismic, gravity and magnetics will allow both previously identified and new leads in the older sections to be more confidently evaluated.
Section through expected bidding areas west of the Porto Basin offshore Portugal reveals Mesozoic fault blocks creating huge closures with sharp imaging of faults.
