A new geological analysis of the Rockall area offshore the UK suggests that previous exploration failures in the area have been due to a misunderstanding of the subsurface.
Exploration in the Rockall Basin, in the North Atlantic, north and west of Ireland and Scotland, has largely unsuccessful to date, with only one gas discovery out of 12 wells drilled.
After studying new seismic data, commissioned by the Oil and Gas Authority (OGA), and employing lessons learned elsewhere on the UKCS, geologists from the University of Aberdeen believe they have gained a clearer understanding of the Rockall Basin and identified potential areas for future exploration activity. It is hoped the work will lead to a boost in exploration activity on the UKCS.
Dr Nick Schofield from the University’s Department of Geology and Petroleum Geology led the analysis. He said: “The Rockall Basin is one of the most challenging environments on Earth when it comes to hydrocarbon exploration, but our analysis has revealed that one of the barriers to success may have been a misunderstanding of the subsurface geology.
“By analysing seismic data provided by the OGA and Petroleum Geo-Services (PGS), and using what we have learned through our work in the Faroe-Shetland Basin, we found that the character of areas where operators hoped to find oil may have been misleading.”
Dr Schofield explained that one issue is the previous targeting of so-called ‘bumps’ in the sub-surface, commonly referred to in the industry as a ‘four-way closure,’ where it is hoped oil has been trapped.
“In the case of Rockall, these bumps, in many cases, appear to have actually been caused by volcanic intrusions in the sub-surface,” he said. “We believe that the oil and gas is more likely to have migrated to the outer fringes of Rockall instead, away from these previous exploration targets.”
The study has identified the eastern edge of the Basin against the Outer Hebrides Shelf as an area of interest for future exploration activity.
The research work was funded by a £250,000 award from the OGA as part of its Frontier Basins Research effort to boost future exploration in the UKCS.
Looking ahead, Dr Schofield said that work will continue to gain an understanding of the area’s potential, using innovative techniques that complement the valuable seismic data provided by the OGA and companies such as PGS, GeoPartners and Spectrum Geo.
“This analysis is very much a starter for ten in terms of our work to gain a clearer understanding of what’s going on in Rockall, and we are using a variety of methods to build on what we have discovered so far,” he said.
“We have also collected data from an aerial drone we have used to map outcrops, for example Kilt Rock on the Isle of Skye, where the rock structure is similar to what you would find in the subsurface and helps us visualize what we can’t see.
“What we are ultimately working towards is the most detailed geological understanding for Rockall which will be made freely available to industry as part of efforts to maximize economic recovery in the UKCS.”
Over the last two years, the UK Government has provided £40 million of funding for seismic acquisition programs, which the OGA has been using to build a regional database of seismic data in under-explored areas of the UKCS. This has included two new seismic campaigns covering the Mid North Sea High and the Rockall Basin in 2015/16 and the East Shetland Platform and South West Britain in 2016/17.
Nick Richardson, OGA Head of Exploration and New Ventures, said: “The seismic acquisition program and subsequent work by Aberdeen and Heriot Watt Universities are an important part of our strategy to revitalize exploration.
“The findings of Dr Schofield’s paper demonstrate the value in applying the latest geological knowledge and understanding to seismic data to increase industry’s awareness of the opportunities that still exist in frontier areas.”
The latest offshore licensing round, the 29th Offshore Licensing Round, which targeted under-explored areas of the UKCS, was the first licensing round in two decades to focus on frontier areas, including the Rockall.
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