Karmorneftegaz, a joint venture between Rosneft and ExxonMobil, has started drilling the Universitetskaya-1 well in Russia.
North Atlantic Drilling's West Alpha rig is being used to drill the well to a maximum depth of 7km.
Rosneft and ExxonMobil have developed an iceberg collision prevention plan to ensure that the rig can operate safely in severe ice conditions.
Drilling operations are expected to take about two months to complete.
Rosneft head Igor Sechin said: "The start of exploratory drilling in the Kara Sea is the most important event of the year for the global oil and gas industry.
"As a result of this work we are planning to discover a new Kara sea oil province. Developing of the Arctic shelf has a huge multiplicative effect on the whole Russian economy."
The Universitetskaya structure covers a 1,200,000km area with a 550m high hydrocarbon trap.
Its resources amount to over 1.3 billion tons of oil equivalent. Around 30 structures were identified in three East Prinovozemelskiy areas of the Kara Sea.
The entire resource base of the three areas is estimated at 87 billion barrels or 13 billion tonnes of oil equivalent.
Rosneft said the sea depth at the drilling site is 81m, and the designed depth of the vertical well is 2,350m from the rotary table.
Image: North Atlantic Drilling's West Alpha rig is being used to drill the Universitetskaya-1 well. Photo: courtesy of Rosneft.