Talk about fortuitous timing. Just as politicians of every shade and stripe are decrying America's dependence on foreign oil, along comes the discovery of a major new field in the Gulf of Mexico that could increase U.S. oil and gas reserves by 50%.

As fellow Fool Matt Koppenheffer explained earlier, a trio of companies -- U.S. major Chevron (NYSE:CVX), Norway's Statoil (NYSE:STO), and the smaller independent Devon Energy (NYSE:DVN) -- announced that they had successfully drilled a deepwater test well that was producing around 6,000 barrels a day in the Gulf of Mexico. Chevron estimates that the 300-square mile region where the test well is located could hold anywhere between 3 billion and 15 billion barrels of oil and natural gas equivalents -- rivaling the discovery of Alaska's Prudhoe Bay a couple of decades back.

Now, before we get all excited and rush to snap up shares of these companies, we need to realize that it will be quite awhile before this field comes online -- 2010 at the earliest -- and there will be substantial upfront costs. After all, Chevron's test well, named Jack 2, was drilled at 28,175 feet below sea level, and the amount of money and equipment needed to lift oil from this depth is likely to run in the billions, if not tens of billions, of dollars.

Simply put, Chevron, Statoil, and Devon will be facing numerous years of much higher capital expenditures before they see any substantial return on their investment ... and success is by no means guaranteed.

That's why, in my Foolish opinion, investors should play this exciting discovery by taking positions in the companies that will provide the services essential to the development of this find -- companies that will profit from that work over the coming years, regardless of the ultimate success or failure of this field.

The two companies that spring to mind are Transocean (NYSE:RIG), the world's leading deepwater driller, and Hercules Offshore (NASDAQ:HERO), the largest liftboat operator in the Gulf of Mexico.

I like Transocean because the discovery was made about 5.3 miles below sea level. That record-setting depth (for the GOM) will demand expertise and rigs possessed by only a few companies -- and Transocean is one of them (Diamond Offshore (NYSE:DO) is another). Since there's already an undersupply of deepwater rigs in the GOM, you can bet your investment dollar that dayrates will continue to climb, as will deepwater drillers' profits.

Hercules, with its fleet of 42 liftboats and 40% share of the GOM market, is another player likely to profit from the exploration of this new field. Liftboats are essentially self-elevating mobile work platforms, enabling these craft to perform all manner of offshore services, such as platform maintenance, rig inspections, repairs, etc. Needless to say, as more rigs deploy to drill the new field, these services will be in increasing demand.

Don't get me wrong; I think that Chevron, Devon, and Statoil are well-run companies that will profit down the road from this exciting discovery, but I like to hedge my bets and focus on the companies that will make profits immediately. I'd urge investors to drill into the prospects of both Transocean and Hercules and see if they draw the same conclusions.

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Fool contributor Will Frankenhoff does not own shares in any of the companies mentioned above. The Fool has a disclosure policy .