Exxon Mobil Corp. vastly expanded its reach in Russia’s Arctic on Wednesday, announcing it had signed an agreement to grow its exploration territory there by more than five-fold.

The world’s largest non-state oil company said Wednesday it had expanded an agreement with Russia’s Rosneft to explore an additional 395,383 square miles off that nation’s frigid northern coast.

The companies also are studying the possibility of a liquefied natural gas project in Russia’s far east, they said in a news release.

The deal expands on a prior agreement that gave Exxon Mobil a partial stake in any finds in a 78,233 square mile territory in the Kara Sea of Russia’s Arctic region. Although Rosneft has agreements with other companies to explore its Arctic, the other deals pale in comparison to the area Exxon Mobil will now have access to. Statoil, of Norway, has the next largest exploration partnership with Rosneft, at about 63,000 square miles. Italian oil giant Eni has struck deals with Rosneft for a smaller reach.

Irving-based Exxon Mobil has held an edge over other companies in continuing negotiations with Rosneft because of its ability to offer ownership stakes in a large range of oil and gas plays, said Brian Youngberg, an analyst for brokerage firm Edward Jones in St. Louis.

Rosneft will also be seeking to learn from Exxon Mobil’s expertise in shale plays, hoping to transfer some of that to Russia.
The result is an expansive new area of prospective resources for Exxon Mobil, though one that will likely take a lot of money and time to develop, said Kent Moors, scholar in residence at the Institute for Energy and the Environment at Duquesne University in Pittsburgh and president of global oil and gas consulting firm ASIDA.

Oil and gas production in the icy Arctic waters is no easy task, a point proven by recent challenges facing Shell in Alaska. Shell has so far spent nearly $5 billion and encountered numerous setbacks in pursuit of completing its first offshore well there.

“Clearly, Exxon’s one of the few companies in the world that can pull this off because this is a huge investment,” Moors said, referring to the possibility of safely producing in Arctic waters. “It’s a huge commitment.”

But the potential of the resources thought to be in the offshore reserves are enormous, Moors said. A 2008 assessment from the U.S. Geological Survey estimated that 90 billion barrels of oil, along with 1.7 trillion cubic feet of natural gas and 44 billion barrels of natural gas liquids, are yet to be discovered in the Arctic.

“Nobody that big can avoid the potential opportunity of getting in on this at the ground floor,” Moors said.

The possibility of large-scale jumps in production is what has driven Exxon Mobil’s involvement in Russia and elsewhere, as it is attempting to add new chunks of oil and gas output to its declining numbers, said Allen Good, an analyst for investment research firm Morningstar in Chicago.

The expanded agreement will give Exxon Mobil the capability to more than double its exploration area in the Kara Sea, while adding areas in the Laptev and Chukchi seas, according to the company. The new territory includes water depths ranging from around 30 feet to more than 6,000 feet, according to Exxon Mobil.

Exxon Mobil also agreed to give Roseneft the option for up to a 25 percent stake in a natural gas production effort in Alaska’s North Slope, the company said in a news release. The company’s Port Thompson project there is estimated to have access to about 25 percent of the known natural gas reserves in the North Slope area, the company said.

“The agreements signed today bring the already unprecedented scale of the Rosneft and ExxonMobil partnership up to a completely new level,” said Igor Sechin, president of Rosneft, in a statement. “The acreage in the Russian Arctic subject to geological exploration and subsequent development increased nearly six-fold. That means the enormous resource potential of Russian Arctic offshore fields will be explored and developed in the most efficient manner with the application of cutting-edge technologies and expertise of our strategic partner, ExxonMobil, and using state-of-the-art environmental protection systems.”

Rosneft is majority-owned by the Russian government. The companies did not immediately disclose what stake each would take in any discoveries in the expanded agreement.

This is one of several collaborations between the two companies in Russia and elsewhere. Exxon Mobil and Rosneft are also jointly developing an on-shore field in Western Siberia. The American giant has a 49 percent stake in that venture to explore and assess the potential of more than 6,000 square miles in that region.

Exxon Mobil footed the $3.2 billion bill for the initial exploration effort in the Kara Sea, which is ongoing.