Norway’s state-owned energy giant Equinor and its partners have achieved a twofold increase of their initial estimate for a gas discovery in the North Sea, revealing recoverable gas and condensate volumes of up to 180 million barrels of oil equivalent (boe) following the drilling of an appraisal well. As a result, the partners are now eyeing a potential subsea tie-back to existing infrastructure to bring more gas to the European market.
The Norwegian Offshore Directorate has disclosed that Equinor, together with its partners, Orlen Upstream Norway, DNO Norge, and Wellesley Petroleum, drilled the 35/7-2 appraisal well about 35 kilometers northeast of the Kvitebjørn field on the 35/7-1 well, also known as the Afrodite discovery, which was made in 2008.
The well 35/7-2, which confirmed the gas and condensate discovery, was the second well drilled in production license 293, awarded in 2003 (North Sea Awards 2002). Equinor’s partner, Wellesley, is the operator of the well 35/7-2, which was drilled by the Deepsea Yantai rig.
The objective of 35/7-2 was to delineate the Afrodite discovery, leading the partners to encounter a 69-meter gas/condensate column in the Tarbert Formation and the upper part of the Ness Formation with reservoir rocks of poor quality. The gas/water contact was not made.
A 4-meter gas/condensate column was found in the lower part of the Ness Formation, with reservoir rocks of poor quality and no gas/water contact. The well encountered reservoir rocks with poor reservoir properties in the Etive Formation. This reservoir was aquiferous.
Extensive volumes of data were collected in the well, as the use of new technology in the data acquisition provided essential information for developing the reservoir, which yielded beneficial learning for use in other tight reservoirs.
The well was drilled to a vertical depth of 4,667 meters below sea level in the Drake Formation, part of the Dunlin Group from the Middle Jurassic. The water depth at the site is 376 meters, and the well is currently being permanently plugged and abandoned.
Preliminary calculations show that the discovery is now between 12 and 29 million standard cubic meters of recoverable oil equivalent, which corresponds to between 77 and 180 million barrels of oil equivalent. The licensees will assess whether it is possible to develop Afrodite via existing infrastructure in the area, where Kvitebjørn is one possible option.
According to Equinor, the new appraisal well shows that the recoverable gas volumes may be more than twice as large as previously estimated, with total volumes in the reservoir about three times as large, but the reservoir properties mean that only parts of the resources can be recovered.
"To find such large gas volumes in a mature area on the Norwegian Continental Shelf is very good. We have long had faith in the Afrodite discovery, and this appraisal well has uncovered volumes far above expectations.”
The reservoir has relatively low permeability, which means that the gas flows slowly through the reservoir rock and makes the resources difficult to recover, so the results from the appraisal well will now be analyzed further.
Equinor considers the discovery to be commercially viable and will continue to work on the possibility of a subsea development tied back to the Kvitebjørn platform so that the gas could be sent via existing infrastructure to the Kollsnes processing plant in Øygarden and on to the European market.
"We are investing aggressively in exploration on the Norwegian continental shelf. Equinor strongly believes that there is still more to be discovered and is working purposefully to increase the likelihood of new and larger discoveries. The results at Afrodite show the potential that still exists in mature areas. At the same time, new discoveries in new exploration areas will be crucial for maintaining production from the Norwegian continental shelf and deliveries of energy to Europe."