After more than a year of disseminating tragic news and noting the finger-pointing among companies involved in the fire and explosion aboard the Transocean (NYSE: RIG) Deepwater Horizon rig in the Gulf of Mexico, it's a pleasure to note positive occurrences in the region. And the sensation only improves when it's tied to a company I've hawked to my Foolish friends more frequently than I can remember.

Now that companies are back to drilling in the deepwater Gulf, ExxonMobil (NYSE: XOM), the biggest member of Big Oil, has quickly checked in with a trifecta of impressive discoveries. Two were of oil, and the third was of gas. They occurred about 250 miles southwest of New Orleans in the Keathley Canyon, in about 7,000 feet of water.

The company is completing a development plan for the area, although it's clear that additional drilling will be required to fully appraise the reservoir. Nevertheless, it appears that the wells could contain a healthy 700 million barrels of oil equivalent. Exxon owns a half-interest in the wells, and Italy's Eni SpA (NYSE: E) and Brazil's Petrobras (NYSE: PBR) are its partners. Other companies operating in the area of the discoveries include Anadarko Petroleum (NYSE: APC) and Chevron (NYSE: CVX).

The Exxon discovery follows by less than two weeks another find by Noble Energy (NYSE: NBL) at its Santiago exploration prospect in about 6,500 feet of Mississippi Canyon water. Noble received the first deepwater drilling permit following the lifting of the Obama administration's deepwater drilling moratorium established in the wake of the Deepwater Horizon tragedy.

ExxonMobil has been busy this week beyond the Gulf of Mexico as well. The company, which became the biggest U.S. natural-gas producer last year when it spent $35 billion to acquire XTO, a major shale gas operator, is forking over $1.69 billion for a pair of Marcellus shale operators. The two companies, Phillips Resources, of Warrendale, Pa., and TWP, of Butler, Pa., are both closely held. The pair, which will add a figure close to their combined year-end reserves of 228 billion cubic feet of gas to Exxon's cache, will be included under the XTO umbrella.

Exxon's continued doling out of funds for additional gas properties is viewed as a positive development for the gas industry in the U.S., which is believed to include about 827 trillion cubic feet of shale gas. Beyond that figure, ExxonMobil CEO Rex Tillerson noted not long ago that the company expects to use its unconventional drilling expertise in Europe, including underexplored Poland.

My strong advice to Fools is to keep close tabs on the varied activity of ExxonMobil, whose shares have risen more than 30% in the past year. Given its size, the vast geographic scope of its activities, and its technological strengths, it appears that the company is deserving of a position on all Foolish watchlists