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* Share buyback starts immediately
* Latest European oil firm to do so
* Johan Sverdrup oilfield starts production
* Last of the giant North Sea fields
* Shares up 7%, best performer of European STOXX index(Adds analyst comment, updates share)
By Nerijus Adomaitis and Terje Solsvik
OSLO, Sept 5 (Reuters) - Equinor on Thursdaylaunched a $5 billion share buyback and said its Johan Sverdrupoilfield, the largest North Sea discovery in more than threedecades, will come on stream in October, a month earlier thanplanned, lifting its shares.
Equinor is the latest European oil firm to launch buybacks,after BP Shell and Total. It will becompleted by end-2022, with the first tranche of $1.5 billionstarting immediately and ending no later than Feb. 25, 2020.
The Norwegian state will maintain its 67% share in the firm.
"We have over the last years built a strong financialposition with solid credit ratings and a net debt ratio around20%," Equinor Chief Executive Eldar Saetre said in a statement.
Shares in Equinor were up 7.3% at 0854 GMT, the bestperformers in the European STOXX 600, up 0.54%.
"The upcoming start-up of the world-class Johan Sverdrupfield, combined with several other new fields in production,provides additional confidence in our outlook for productiongrowth and increased cash generation capacity," said Saetre.
Analysts at Bernstein said the Equinor share buyback was"decent compared to peers" and the Sverdrup field would be amajor driver of earnings for the company.
They also pointed to Equinor's estimate that the operationalexpenditure of the field would be below $2 per barrel of oilequivalent. Bernstein said this was even lower than SaudiAramco's $2.8/boe.
"Both announcements are clearly positive," Bernstein said ina note to clients.
LAST OF THE GIANTS
Discovered in 2010, Sverdrup may be the last of the giantNorth Sea oilfields. Nothing of that size has been found since,and it is Norway's biggest industrial development by far. Thereare no other field developments of that size planned in thecoming years.
Its start-up will significantly boost the North Sea region'scrude oil shipments and the cash flow of the field's owners.
Trading sources last Friday told Reuters that Equinor hadlisted 11 possible Sverdrup oil cargoes for October shipment,but the company said at the time that a November start was stillits primary target.
The field's first phase is projected to reach a peak outputof 440,000 barrels per day of oil in summer 2020.
The second phase of Sverdrup is expected to come on streamin late 2022, after which output could reach 660,000 barrels perday, Equinor added.
In addition to Equinor, Aker BP, LundinPetroleum, Total and Norwegian state firmPetoro are licence holders in Sverdrup.
Alongside the share buyback, Equinor will continue to growits dividends, keep investing in new assets and maintain its netdebt ratio in a range of 15-30%, Chief Financial Officer LarsChristian Bacher told Reuters.
For now, Equinor was keeping its full year 2019 productionguidance unchanged. It is expected to be at similar levels as in2018, while capital spending is still seen at $10-11 billion, hesaid.
Asked whether Sverdrup could be the last of the bigdiscoveries off Norway, Bacher said: "I hope not."(Writing by Gwladys Fouche; Editing by Stephen Coates/SherryJacob-Phillips/Jane Merriman)
