As I look back at the key events in energy during 2009, I'm struck by one particular trend, which likely will have a major impact on the oil and gas industry for years to come.

The trend involved the success of the industry's companies drilling for oil and gas in the deepwater areas of Brazil, the Gulf of Mexico, and West Africa. The three locations comprise what is known as the Golden Triangle, and their impact on energy worldwide is just getting started.

Probably the deepwater area that's received the most attention during the past year is the Santos Basin of Brazil, where Petrobras (NYSE:PBR) and several of its friends, including ExxonMobil (NYSE:XOM) and Hess (NYSE:HES), hang out. It's been little more than two years since Petrobras made its noteworthy discovery of the Tupi field in the basin.

Expectations continue to hold that Tupi probably contains up to 8 billion barrels of oil equivalent. Petrobras has just announced that it'll hasten the progress of a pilot development project in the Tupi field.

But don't sell the Gulf of Mexico short. During the first 11 months of the year it was the site of a dozen discoveries made in no less than 1,000 feet of water. Finds were made by such companies as BP (NYSE:BP) and Chevron (NYSE:CVX) in an area known as the Keathley Canyon located in the Lower Tertiary, which lies miles beneath the sea floor and is beset by high temperatures and pressure, which will continue to bring on new production challenges.

In February, Chevron, drilling in about 7,000 feet of water, made its Buckskin discovery but also encountered a string of dry holes. Then, in September, BP discovered the Tiber field after drilling the deepest well ever. There are those who believe that, as the new wells begin to produce, the Gulf's total deepwater output could reach 2 million barrels per day in two years, up from 1.3 million barrels in 2008.

And then there's West Africa, which consists of several parts, including Nigeria, Angola, and a potentially huge formation that may stretch the 700 miles from Sierra Leone to Ghana. Numerous companies, including Anadarko (NYSE:APC) and Marathon (NYSE:MRO), chalked up deepwater discoveries in one or another of these areas during the year.

How should you play this major trend? While all the companies named have their strengths, I'm inclined to dip into the shares of BP, which continues to find oil just about everywhere.

BP's strengthening during the past couple of years has landed it in the Motley Fool CAPS five-star category. Why not head for the company's CAPS page and cast your vote?

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Fool contributor David Lee Smith doesn't own shares in any of the companies mentioned above. He welcomes your comments or questions. The Fool has a disclosure policy that simply won't sink.