Ironic, isn't it? Here we are in the midst of a mini-boom in oil prices, yet many major oil companies find themselves with dwindling reserves and struggling to maintain production levels.

One of the few oil majors that doesn't have that problem is Italy's Eni S.p.A. (NYSE:E). With successful development efforts in places like Libya, Nigeria and Angola, Eni has managed to keep adding meaningful amounts of reserves while still increasing production.

For the first quarter of 2005, Eni said it managed to increase production by about 4.6% to 1.7 million barrels of oil equivalent each day. Fueled by higher production and better prices, net revenue from operations grew 20% for the quarter.

Improved margins were also an important story for the quarter. Operating income climbed 39.2%, while net income ticked up over 44%. The exploration and production business was the primary factor behind improved income, as segment operating income rose 55% on slightly higher volume and significantly higher oil prices.

While the gas- and power-utility business posted pedestrian operating income growth of 1%, it still contributed over one third of Eni's operating income for the quarter. Other businesses such as petrochemicals and refining showed considerable percentage growth in operating income, but combined to contribute less than 10% to the total.

Due in part to being an Italian company, Eni is a little different than most other major oil companies. The Italian government still owns a sizable chunk of Eni. What's more, Eni isn't bound by some of the restrictions that affect American oil companies. Consequently, the company is able to conduct operations in countries like Iran. It often finds a more welcoming reception in other areas where relations with the U.S. are strained.

Among the top ten oil producers (measured by market capitalization), only Petrobras (NYSE:PBR) has a higher debt ratio than Eni. But only PetroChina (NYSE:PTR) offers a better dividend yield.

Staying within the top ten, valuation is a little tricky. Only ExxonMobil (NYSE:XOM) has a higher P/E, and none of the ten has a lower return on equity (though Eni's is still above 20%). But as I mentioned earlier, Eni is one of the few majors adding to its reserve base and upping production in a meaningful way.

As a result, I think Eni is an interesting opportunity -- particularly for investors who want to add some income or international exposure (or both) to their portfolio. It's neither the best-run nor the cheapest major oil company, but increasing reserves and a generous payout can go a long way toward balancing the scales.

Whether you call it black gold, Texas tea or just oil, we have more info for you:

Fool contributor Stephen Simpson owns shares of PetroChina. The Fool has a disclosure policy.