Exxon Mobil Corp reported a fourth-quarter profit on Monday that topped Wall Street expectations as natural gas projects boosted results at the largest U.S. oil company's exploration arm.

Still, Exxon's net income fell 23 percent as weak demand for fuel in the global economic slowdown caused a loss in its refining business.

Exxon's shares rose 3 percent, outperforming a 2.2 percent gain in the Chicago Board Options Exchange index of oil companies <.OIX>.

Oil and gas production increased nearly 2 percent in the quarter to 4.18 million barrels of oil equivalent (BOE) per day -- better than some analysts had expected -- helped by production from Exxon's massive liquefied natural gas (LNG) projects in Qatar.

Natural gas production in Asia Pacific and the Middle East was up 31 percent, Pavel Molchanov, analyst at Raymond James, said. That's where a lot of the growth came from. They had those big liquefaction terminals start up in Qatar in the second half of the year.

Exxon is also investing in natural gas closer to home. The company has said it plans to buy XTO Energy Inc for about $30 billion in stock in a big bet on North America's fast-growing natural gas industry.

While the company declined to provide any details of the planned XTO acquisition on its earnings conference call, it did say the deal is still expected to close in the second quarter.

Underscoring Exxon's interest in developing fields with so-called unconventional gas trapped in substances like rock, the company said it has amassed 5.5 million unconventional gas acres worldwide and is accelerating development of the Marcellus Shale in the eastern United States with a joint-venture partner.

REFINING LOSS

Exxon and other companies that process oil into gasoline, diesel and heating oil have seen refining margins crushed as crude prices climbed more than 30 percent in a quarter where industrial demand was depressed by economic weakness.

Net income in the quarter was $6.05 billion or $1.27 per share, compared with $7.82 billion, or $1.54 per share in the same period a year earlier.

Wall Street analysts had expected a profit of $1.19 per share, according to Thomson Reuters I/B/E/S.

The two things I like to see drive an earnings beat are better production and better margins, Phil Weiss, oil analyst at Argus Research, said. They certainly got the production.

Exxon's worldwide refining unit had a loss of $189 million, compared with a year-ago profit of $2.41 billion.

Last week, No. 2 U.S. oil company Chevron Corp posted a 37 percent drop in quarterly profit, while top U.S. refiner Valero Energy Corp sank to a quarterly loss and slashed its dividend.

Exxon's chemical earnings were $716 million, up sharply from $155 million in the 2008 fourth quarter. The company's exploration arm earned $5.78 billion, up from $5.63 billion a year ago.

Revenue in the quarter rose 6 percent to $89.84 billion,

Exploration and capital spending totaled $27.1 billion in 2009, up nearly 4 percent from a year ago. The company has said it expects to spend $25 billion to $30 billion each year over the next 5 years.

Exxon shares closed $1.75 higher at $66.18 on the New York Stock Exchange and rose slightly to $66.25 in after hours trading.

BP Plc will report on Tuesday and Royal Dutch Shell Plc will release results on Thursday.

(Additional reporting by Matt Daily in New York; Editing by Dave Zimmerman and Richard Chang)

Energy