Strong Roots and New Growth

Exploration in the Southern Gas Basin has its roots in the very earliest successes of the European gas industry, and the discovery of the onshore Groningen gas field by the Slochteren-1 well in 1959 when gas was discovered in Permian-aged Rotliegende sandstones. This reservoir was to become a significant target in the basin as the first offshore exploration wells in the North Sea targeted the Rotliegende sandstones beneath the Zechstein salt sequence, and the first commercial gas discovery was made in 48/6-1. This was to become the West Sole gas field.

More than 50 years later, the basin continues to attract explorationists pursuing established plays but also progressing new ideas in underexplored targets. It is not uncommon for mature basins to undergo periods of rejuvenation, but this time it’s different, with the focus on traditional gas exploration occurring alongside new energy developments in hydrogen, carbon storage, and other energy transition projects. It is within this new context that significant opportunities could exist for PGS to leverage its fully integrated geophysical capability and create new value streams in new energy.

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In April 2022, PGS announced the SNS Vision project, one of several exciting seismic rejuvenation projects to re-process vintage data in mature areas. The project will deliver over 12 000 sq. km of PSDM-merged, reprocessed data in a single volume and sets the stage for a new class of seismic data product that will not only enable the evaluation of new exploration prospectivity but also the assessment of energy transition opportunities.

Alongside SNS Vision, PGS is winning accolades as a preferred supplier in the energy transition space with the recent seismic acquisitions, including the BP-operated Endurance carbon storage site, a cornerstone of the Northern Endurance Partnership.

A transitional theme connects the conventional with new energy opportunities in and around the basin reflecting the changes now transforming the energy sector. The journey to net zero is a stepwise process, not an abrupt change. Hence, the ability to find more gas resources in provinces that are envisaged as key, future net-zero energy hubs and clusters, is essential to their success and long-term viability. Establishing markets and infrastructure for blue hydrogen production (with CCS) via established, industrial-scale processes (e.g., steam methane reforming) will set the scene for the future expansion of green hydrogen, a technology that remains under development and is yet to scale. This is why data rejuvenation products like PGS’ SNS Vision are now so relevant: they serve the dual imperatives of energy security through continued energy supply (i.e., gas) and the need to deliver the energy transition to net-zero, by enabling the industry to combine secure access to the gas it needs and provide sites to store carbon and help neutralize industrial emissions.

Opportunities in Permian Plays

What are the technical opportunities? In the conventional exploration domain, the last few years have seen a re-appraisal of under-explored plays motivating new activity. Perhaps the best example of this is the Permian Zechstein Reef play, which is on the margins of the traditional fairways that have been successfully explored. 2022 will see this play tested by Shell and Deltic Energy, and success here can be expected to drive further activity in the region. This activity is off the back of other finds in the last decade, further to the south, closer to the SNS Vision area and the infrastructure-rich heartland of the Southern Gas Basin. New discoveries in old plays continue to feature the Permian Leman Sandstone, the reservoir that started it all. Significant examples include the Tolmount Field and its satellites, which bring the story right up to date, with the field commencing its first gas production in April 2022.

Targeting the Bunter Sandstones

There is also significant recent activity in CCS, with a focus on the development of the BP-operated Endurance storage site and award, in May 2022, of two further CCS licenses near Endurance, to BP and Equinor, two of the members of the Northern Endurance Partnership. CCS development in the region currently targets the Triassic Bunter sandstones. This reservoir is not usually a priority exploration target, sitting above the Zechstein evaporite seal, and being challenged by access to deeper hydrocarbon sources. However, its position above mobile Zechstein salt has resulted in an attractive configuration of relatively simple structural closures beneath a regional seal, readily imaged on seismic data.

Many of these features are known to exist within the SNS Vision project area and PGS has just completed a new survey over the most prominent of these, the Endurance structure. This feature has already been assessed as viable for carbon storage, with the Quad 42 structure being tested by the 42/25d-3 well in 2013. Following PGS’ acquisition of the 3D seismic data over Endurance, the partnership is now set to continue the development of the region’s first offshore CO2 storage site, storing up to 100 million tons of CO2 over the 25-year lifespan of the project, receiving captured emissions from a diverse range of industrial emitters in the region. Topping off recent seismic acquisition activity by PGS over Endurance, the project has received another boost with the news that Equinor and BP have been offered two further storage licenses by the NTSA.

Get Ready for the Next Chapter

The positive news flow does not end there. On 14 June 2022, we witnessed another important milestone in UKCS history with the announcement by the NSTA of the UK’s first carbon storage license round. No less than eight areas are made available for competitive bids in the Southern North Sea, definitively setting the scene for the next phase of the basin’s rich history as an important energy province well into the 21st Century.

With the North Sea emerging as a key new energy hub, the SNS Vision project will support assessments of the shallow subsurface alongside carbon and energy storage, helping to de-risk wind, CO2 storage, and traditional exploration activities.