* PGNiG expects 2013 output to rise to 4.8 bln cubic metres
* Q4 net profit $687 mln, below expectations
* Boosted by Gazprom deal, but not as much as expected
By Agnieszka Barteczko
WARSAW, Mar 19 (Reuters) - Polish gas monopoly PGNiG said the start of production at the Skarv field offNorway should help boost its gas output by 12 percent this year,reducing Poland's reliance on Russian energy imports.
Production at Skarv, a big project by North Sea standardswith an expected life of 25 years, started in January. PGNiGowns 12 percent of the project, its biggest in Norway and partof a drive by Poland to diversify its energy resources.
PGNiG disappointed on Tuesday with a fourth-quarter netprofit of 2.2 billion zlotys ($687 million), showing asmaller-than-expected boost from an agreement with Russia'sGazprom that allows it to import Russian gas at alower price.
Analysts had forecast a net profit of 2.4 billion zlotys,versus 431 million in the fourth quarter of 2011.
"The difference concerns the size of the retroactive bonusfrom Gazprom. I assumed that it would be significantly higher,"Lukasz Prokopiuk, an analyst at DM IDM said.
He forecast full-year net profit would rise to 3 billionzlotys in 2013, from 2.24 billion in 2012.
PGNiG and Gazprom agreed in November that PGNiG would payless for gas imports from Russia, which supplies most of thenatural gas that Poland burns each year.
PGNiG said that thanks to the Gazprom deal, which had aretroactive effect, its fourth-quarter earnings before interest,tax, depreciation and amortisation (EBITDA) increased by about 3billion zlotys.
The group's shares have rallied 47 percent since the dealwas announced to record highs, but were down 0.3 percent by 1105GMT on Tuesday. They still outperformed Warsaw's blue chip WIG20index, which was down 1 percent.
PGNiG is also probing shale gas prospects on the Baltic Seacoast, as Poland is counting on untapped shale gas reserves tohelp it become less dependent on Russia.
Poor drilling results so far and a lack of detailed legalregulation, however, have caused some doubts about Poland's trueshale gas potential.
PGNiG forecast gas output will rise to 4.8 billion cubicmetres this year, and 0.3 bcm of that will come from Norway.
In 2012 it sold 14.9 bcm of gas, 4.3 bcm of which came fromits own production while the rest was imported from Russia.