A competent persons report has set a proved and probable (2P) gas reserves of 303bn cubic feet, which would amount to 54mln barrels oil equivalent. It represents a huge upgrade from the previous estimate, of 34bn cubic feet of gas.
The Vulcan Satellites account for some 248bn cubic feet of the 2P reserves, while the Blythe and Elgood are estimated to have 33bn and 22bn cubic feet of gas.
Peak production was estimated in excess of 35,000 barrels oil equivalent per day.
IOG added that an additional competent persons report is anticipated, which is expected to see significant resources estimated for the Harvey asset.
"We are extremely pleased with the results of the CPR on our SNS development portfolio,” said Mark Routh, IOG chief executive.
He added: “This is a major landmark for our portfolio and clear vindication of our strategy of acquiring neglected and stranded assets at low cost, to be commercialised via our gas hub strategy using the Thames Pipeline export route.
“In addition to confirming substantial volumes, the classification as reserves is a key step towards securing development funding.
“Our submission of the Field Development Plan for the Vulcan Satellites hub, expected later this month, will be the next important step in that regard. We also expect to confirm further key project contractors in the coming weeks.”