Exxon Mobil Corp, the world's largest publicly traded oil company, said on Friday its crude oil and natural gas reserves rose slightly in 2013, lifted by projects in U.S. shale fields and Abu Dhabi.

Proved reserve additions of 1.6 billion barrels oil equivalent from places like the Permian Basin in Texas and the Bakken Shale in North Dakota helped Exxon replace 103 percent of its 2013 output, the Irving, Texas company said in a statement.

In 2012, Exxon's reserve replacement ratio, a key measure of growth for investors, was 115 percent.

At year end, Exxon's proved reserves totaled 25.2 billion oil-equivalent barrels. The reserves were 53 percent liquids, which typically bring higher profits.

Shares of Exxon fell 9 cents to $95.28 in morning trading on the New York Stock Exchange.