Natural gas has many advantages over other fossil fuels. It's cleaner, and when burned produces less carbon dioxide emissions than oil or coal. It is also extremely abundant in North America, and thanks to technological advances involving horizontal drilling and hydraulic fracturing, these huge reserves in the Marcellus, Haynesville and other shale plays are starting to be produced. The charge is being led mostly by the independent exploration and production companies. (For a primer on the oil industry, refer to our Oil and Gas Industry Primer.)

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The list of the five largest producers of natural gas in the United States in the second quarter of 2009 might come as a surprise to some investors.

1. XTO Energy (NYSE:XTO) is the largest producer of natural gas, at 2.352 Bcf per day. The company has a well-diversified domestic base of properties including virtually every promising shale play in the U.S., where the company has 30% of its daily production.

2. BP, Inc. (NYSE:BP), which is number two, is the only major integrated oil company on the list. It produced 2.339 billion cubic feet (Bcf) of natural gas per day.

3. Anadarko Petroleum (NYSE:APC) is third with production of 2.336 Bcf per day. Interestingly, the company's main base of production is not the shale plays that its peers have decided to focus on, but in the Rocky Mountains area, where it has acreage in several different fields including the Powder River Basin and the Pinedale.

4. Chesapeake Energy (NYSE:CHK) is fourth with 2.245 Bcf per day of natural gas production. Chesapeake Energy has been one of the leaders in developing the shale plays in North America, with leading positions in the Haynesville, Marcellus, Barnett and Fayetteville Shales.

5. Devon Energy (NYSE:DVN) is fifth on the list with 2.129 Bcf per day of production. Devon Energy dominates the core area of the Barnett Shale in the Fort Worth Basin in Texas where it has a little more than half its total natural gas production. The company has nearly 4100 producing wells here.

Surprising Finish
Despite its size, Exxon Mobil (NYSE:XOM) is ninth on the list, with production of 1.243 Bcf per day in the second quarter of 2009. Exxon Mobil might have been better off reducing its stock buybacks and putting some more money into its domestic capital exploration program.

One thing to mitigate this trailing position by Exxon Mobil, and other integrated oil companies is that they have substantial international operations, which might explain why they have not focused as much in the United States. Exxon Mobil also has a promising shale play in the Horn River Basin in Canada, which when developed, might jumpstart its growth on the continent.

The Bottom Line
While the major integrated oil companies looked overseas for oil and natural gas, the independent exploration and production companies combed the U.S., employing technology to unlock natural gas reserves once thought uneconomic.

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