The world is obviously waiting raptly for an indication of the next occurrence in the chaos gripping Ukraine. Even with Russia potentially backing down in what has become something of a geopolitical circus, more than a few investors may not have considered that one company in particular, ExxonMobil (XOM 0.39%), could be affected severely by an increasingly contentious relationship between Russia and its now topsy-turvy onetime satellite.

Ukraine and surrounding countries.

You know, of course, that nearly three years ago Exxon and Russia's giant state-controlled oil company Rosneft OAO carved out a deal to work together exploring the potentially prolific Russian Arctic. Also included were plans for the two companies to engage in joint operations in the Western Siberia shale and the Black Sea.

Big money for a huge deal
The original deal was to include an initial expenditure of $3.2 billion just to explore the Kara Sea in the frigid Arctic. Also part of the agreement was the granting of rights to Rosneft for stakes in a portion of ExxonMobil's U.S. shale plays. And in a separate agreement, the Russian company received a 25% interest in Exxon's Point Thomson Project, a natural gas venture in Alaska.

It won't surprise you to know that Russian authorities have a history of not playing fairly with others. Exxon has for years overseen the Sakhalin-1 project on the country's island of the same name. The desolate 500-mile swath of land is located in the Sea of Okhotsk, east of the country.

Royal Dutch Shell (RDS.B) was once the operator of Sakhalin-2, a similar effort on the island. But after spending $20 billion of its own money, the company was forced to sell half its interest in the project to Gazprom, the massive state gas company, for a bargain-basement price.

Hardly a lingering love affair
Beyond that, Exxon's relationship with Russia's leaders has hardly been consistently amicable. In the spring of 2007, The Wall Street Journal reported in a lead article that the company's relationship with the Russian government was becoming progressively more contentious. During his company's annual meeting the same year, ExxonMobil CEO Rex Tillerson stated openly that the big Texas-based company would require more clarity about how the Russian government would treat foreign companies before Exxon would undertake more projects there.

But Exxon isn't the only major integrated oil company that could be affected by increased contretemps between Russia on the one hand and Europe and the U.S. on the other. Last year, after participating for a decade in TNK-BP, a challenging 50-50 joint venture with a group of Russian oligarchs, BP and the Russians both sold their interests in the venture to Rosneft for a $55 billion total. BP came away with $16.65 billion in cash and a nearly 20% interest in Rosneft. I wouldn't be at all surprised, however, were BP eventually to be squeezed out of its stake for a thin sliver of its actual value.

Threatening Big Oil's Ukraine plans
There also is a group of western companies preparing to begin exploratory drilling in Ukraine, an effort being undertaken with an eye toward reducing the country's dependence on Russian gas. Those plans obviously would be threatened by a Russian takeover of its neighbor.

For instance, Shell's docket for the year includes the drilling of 15 appraisal wells in eastern Ukraine's Yuzivska field. That effort is slated to cost a not-inconsequential $10 billion. And Chevron (CVX 0.57%), the second-largest U.S. oil company, is prepared to spend about $400 million to begin operations in Ukraine's Oleska shale formation.

Even Exxon was ready to ink an agreement for drilling in the Skifska area of Ukraine's portion of the Black Sea. That now-tabled effort was to have involved a pair of offshore wells to be drilled at a total cost of about $735 million.

Foolish takeaway
There's lots more that could be said about the possible impact of an expanded Russian incursion into Ukraine. Clearly, such a movement would also have a substantial bearing on global crude (and perhaps natural gas) prices. But for now I urge Fools in general -- and especially those with a taste for energy -- to keep a close eye on the progression of events in both Ukraine and Russia.