* Samburg field initial output seen at 43,000 boepd
* Samburg output to rise to 145,000 boepd in 2015
* Eni CEO not worried about possible Libya contract reviews (Adds details, combines previous stories, changes dateline)
By Melissa Akin
SAMBURG FIELD, Russia, April 20 (Reuters) - Italy's oil and gas major Eni and its partners have started gas production at the Samburg field in Russia's western Siberia as the group aims to boost its clout in the largest natural gas producing region in the world.
The initial gas and liquids output of the Samburg field, operated by Severenergia, is seen at 43,000 barrels of oil equivalent per day (boepd), with Eni's share at 14,000 boepd.
It is expected to rise to 145,000 boepd in 2015, Eni said on Friday.
Severenergia is a joint venture between Gazprom's oil arm Gazprom Neft and Russia's top non-state gas producer Novatek as well as Italy's Eni and Enel.
The gas produced will be sold to Gazprom, while Eni will retain the buy back and marketing rights on the Russian market. The condensates will be destined for foreign markets, Eni said in a statement.
Samburg is Eni's first start up in the Yamal Nenets region where the company has a total of four giant gas and condensate fields to develop, it said.
Eni has been present in upstream operations in Russia since 2007 when it bought stakes in three Russian companies operating in the exploration and development of natural gas reserves: OAO Arctic Gas Co, ZAO Urengoil Inc and OAO Neftegaztechnologia, which are managed by Severenergia, Eni said.
Russia is the second-largest gas producer in the world after the United States, and produced 589 billion cubic metres in 2010, according to the BP Statistical Review of World Energy.
Eni is not worried about potential revisions of its contracts in Libya where it expects to produce about 260,000 barrels per day at the end of 2012, some 10 percent below pre-war levels, Eni Chief Executive Paolo Scaroni told Reuters.
Libya, where Eni is the biggest foreign oil operator, has started investigating foreign oil companies over their past relationships with the former government of Muammar Gaddafi. .
"No... not at all," Scaroni told Reuters when asked if he was worried that Eni's contracts in Libya could be revised.
(Reporting by Melissa Akin, writing by Svetlana Kovalyova, editing by William Hardy)