Norway's Statoil has sold stakes in North Sea oil fields to Austria's OMV.
The $2.65 billion deal will give the former cash to develop new projects and placing the latter on course to meet ambitious output targets.
Analysts said the deal came at a comfortable premium.
It gives OMV a foothold in one of Norway's biggest future oil developments and underlines a rebound in North Sea investments driven by a string of new oil field discoveries as well as high oil prices and better recovery technology.
Statoil sold minority stakes in the mature Gullfaks field, the brand new Gudrun development, Chevron's Rosebank field in the UK and BP's Schiehallion field.
OMV will cover Statoil's capital expenditure between January 1 and the closing of the deal, meaning it could be worth as much $3.15 billion in total.
It also agreed optional cooperation in 11 of Statoil's exploration licences in the Norwegian North Sea, West of Shetland and the Faroe Islands.
That cash - in addition to funds earmarked for projects it will no longer own - gives Statoil a sizeable budget to fund new projects, push on with new exploration and appease investors worried about soaring capital expenditure.
"The idea is to use the proceeds to reinvest in high-return projects," Statoil chief executive Helge Lund said. "It will increase our financial flexibility in the sense it releases $7 billion in future capital expenditure from these assets,'' he added.
Statoil needs to pay for the development of the giant Johan Sverdrup field in the North Sea, which it estimates could hold up to 3.3 billion barrels of oil, as well as huge discoveries in Brazil, Tanzania and Norway, while simultaneously pushing ahead with an aggressive exploration portfolio.
Lund said the deal would not affect its ability to deliver on its 2.5 million-barrel target for 2020.
OMV said it would use proceeds from divesting petrol stations in the Balkans, its lubricants business and a stockholding unit to partially fund the deal, which it said should contribute more than $500m a year to operating profit from 2014, assuming stable oil prices.
For OMV, in the process of exiting lower-margin downstream operations to focus on more lucrative upstream business, the deal gives that effort, cheered by analysts, a major push.
The deal lifts OMV's proven and probable reserves by about 320 million barrels of oil equivalents, or about 19%, and will boost production by about 40,000 barrels in 2014 and almost 60,000 barrels in 2016. That is enough to put it well on course to meet its 2016 target of lifting production to around 400,000 barrels a day from 297,000 barrels in the second quarter.
OMV has already bought into Statoil's Aasta Hansteen's gas project in the Norwegian Sea and taken a stake Lundin Petroleum's Edvard Grieg field, giving it a big exposure to future Norwegian production.