It appears that ExxonMobil (NYSE:XOM) is buying its way into one of the newest oil and gas venues. Indeed, it's a thrill a minute for energy in Africa these days. And now, by spending a reported $4 billion on one of the most recent areas of success, the biggest of Big Oil has in a way legitimatized the new play.

You may recall that a couple of weeks ago I told you that a group led by Texas-based Anadarko Petroleum (NYSE:APC), along with Spain's Repsol (NYSE:REP), the U.K.'s Tullow Oil, and Australia's Woodside Ltd., had found oil and gas off the coast of West Africa's Sierra Leone in a structure that may stretch from that country to Ghana, as much as 700 miles to the east. Anadarko had found a large discovery, perhaps 1.8 billion barrels of crude, in the Jubilee field offshore Ghana a couple of years ago -- the field in which Exxon has now invested.

There is no confirmation that the structure is anywhere near as large as I've alluded to. But with Exxon opening its wallet, the possibilities appear somewhat more likely. Indeed, the oil industry has become more positive about the area of late, so you'll undoubtedly read about a bevy of wells being drilled there in the months and years ahead.

Indeed, we could have another Nigeria or Angola on our hands. BP (NYSE:BP) has just announced an amazing 19th discovery in Block 31 offshore Angola. Its partners in the find were Exxon, StatoilHydro (NYSE:STO), Marathon (NYSE:MRO), Total (NYSE:TOT), and Sonangol, the Angolan state oil company. As such, while Brazil continues to be the focal point for the world's new oil and gas discoveries, Africa, with its multiple productive locations, is not to be ignored.

And while all this is going on, ExxonMobil is also displaying what the company terms "its leadership across the natural gas value chain" at the WorldGas 2009 Conference in Buenos Aires. As many Fools know, my strong feeling is that, within a few years, natural gas and liquefied natural gas will be the most important sources of energy on our planet. With Exxon currently selling 11 billion cubic feet daily, the company will likely remain a dominant player among the publicly held oil and gas companies.

On that basis alone, I would urge Fools to get to know ExxonMobil better, and to consider stashing a few of its shares in their portfolios.

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Fool contributor David Lee Smith doesn't own shares in any of the stocks mentioned above. He does solicit your questions and comments. The Motley Fool's disclosure policy is more powerful than the strongest diamond bit.