Norwegian energy group Statoil said this week it had signed a preliminary deal with Russia's top oil firm LUKoil to extend their cooperation in the Caspian Sea. The deal came during a visit to Norway by President Vladimir Putin, who headed a Russian delegation including leaders of some of Russia's big energy firms and Oil Minister Igor Yusufov. Non-OPEC member Norway is the world's third biggest oil exporter behind Saudi Arabia and Russia. "We have now written a memorandum of understanding to look at further cooperation in the Caspian," Kai Nielsen, a Statoil spokesman, told reporters. "The deal mentions a field in the Russian part of the Caspian called Yalamo-Samur," Nielsen said. "We expect this to be a big field." But Statoil executives declined to say how large the field's resources are likely to be. "That's what we are going to try to find out, but it's too early to say anything more right now," Statoil Chief Executive Olav Fjell told Reuters on the sidelines of a meeting between Norwegian and Russian oil industry executives. Statoil already holds an 8.6 percent stake in the Azeri-Chirag-Gunashli field, which produces about 125,000 barrels a day, and is involved in exploration at the Shah Deniz, Alov, Araz and Sharg fields in the Caspian Sea, the Russia Journal wrote.