* First phase to cost $16.4 billion to $19.7 billion
* Plateau production now seen at 550,000-650,000 boe/d
* Recovery rate 70 pct, output could last 50 years
* Resource estimate maintained at 1.8-2.9 bln boe
* Lundin, Det norske shares gain (Adds analyst, shares, background)
By Gwladys Fouche and Balazs Koranyi
OSLO, Feb 13 Norway's Johan Sverdrup oilfield, the biggest North Sea find in decades, will produce more at its peak than earlier thought and initial development costs will be below forecasts, operator Statoil said on Thursday.
The field, a key plank in Norway's plans to revive oil production after a decade-long decline, will start up at the end of 2019 and the initial phase will also be bigger, producing more oil than analysts had anticipated.
"The update is very positive, implies reduced uncertainty," Teodor Sveen Nilsen at Swedbank wrote in a note to clients. "Indications for plateau production, recovery rate and capex are all better than we have assumed."
The field, a chance find in an area already considered almost fully explored, will produce between 550,000 and 650,000 barrels of oil equivalent per day (boe/d), compared with earlier guidance for above 500,000, Statoil said.
"Johan Sverdrup is among the largest oilfields on the Norwegian shelf, and will at peak contribute with 25 percent of the production from the Norwegian shelf," Statoil said.
It contains between 1.8 billion and 2.9 billion boe, in line with earlier estimates. Statoil said it aimed to recover 70 percent, about twice the global oil recovery rate.
The first phase of development will cost between 100 billion and 120 billion crowns ($16.4 billion to $19.7 billion), below Det norske's guidance and under analysts' estimate for $22 billion, with production initially seen at 315,000 to 380,000 boe/d.
"This first phase is larger than anticipated (200-300 kboepd expected) and should mean some production is accelerated in the development, bringing an uplift to our valuation," JPMorgan said.
The development is key for the project's owners - Statoil, Det norske, Sweden's Lundin Petroleum and Denmark's Maersk Oil, a unit of shipping empire Maersk , and Norwegian state holding firm Petoro.
At 0912 GMT, shares in Lundin were up 5.3 percent, Det norske had gained 3.4 percent and Statoil was down 1.4 percent.
Statoil committed to powering the first phase of Sverdrup from the shore, a key move in the government's efforts in reducing carbon emissions. It did not commit to power from the land for the entire area, known as the Utsira High, home to other developments.
The government has pushed oil firms to power platforms from the shore, where hydro generation is in abundance, to stop them from burning fuel offshore.
"This is too weak. Statoil is not fulfilling parliament's express wish," Terje Lien Aasland, the opposition Labour Party's climate spokesman, told news agency NTB.
Parliament will need to approve the development plan before the firms can begin, but analysts said the power issue was not as acute as earlier thought.
Statoil said it would still consider land-based power for all of Utrisa High before submitting a development plan in early 2015.
"We had feared that an electrification from shore could imply capex way above our total capex estimate of USD 11/boe. This is not a major risk factor any more," Swedbank's Nilsen said. (Additional reporting by Terje Solsvik; Editing by Mark Potter and Dale Hudson)