(Adds result details, Argentina expansion)
By Ernest Scheyder
April 9 (Reuters) - Chevron Corp, the second-largest oil company in the United States, said on Wednesday it expected first-quarter income to slip because of high currency conversion costs and environmental charges in its mining unit.
Output from the company's oil and natural wells fell because of bitterly cold weather throughout the United States, Canada and Kazakhstan.
The company, which operates in about 180 countries, expects foreign currency exchange charges of $100 million for the first quarter.
Chevron plans to list impairment charges of $400 million to $500 million, most of which would be related to its mining operations.
The company operates an underground molybdenum mine in New Mexico, though now-closed parts of the facility have been deemed a superfund environmental cleanup area by the U.S. Environmental Protection Agency.
Excluding the charges, Chevron said results should be "comparable" with the fourth quarter, when it reported net income of $4.93 billion, or $2.57 per share.
Analysts expect first-quarter earnings of $2.77 per share, according to Thomson Reuters I/B/E/S.
Chevron's average U.S. oil and natural gas production fell to 637,000 barrels of oil equivalent per day (boed) in January and February from an average 650,000 for the entire fourth quarter.
Worldwide, the company's output rose slightly, with the company producing 1.94 million boed, up from 1.93 million boed in the first quarter.
Chevron has previously forecast plans to produce 2.6 million boed this year.
Part of the increase will come in Argentina's Vaca Muerta shale oil and gas formation, which Chevron is developing alongside state-controlled YPF. The play is thought to be one of the biggest energy reserves in the Western Hemisphere.
Roughly 17 rigs will be drilling 140 new wells in Vaca Muerta this year, Chevron estimates, helping the play's production grow from about 15,000 boed to 80,000 boed by 2017.
Chevron is scheduled to report quarterly results on May 2 and hold its annual shareholder meeting on May 28.
Its shares fell slightly to $118.91 in after-hours trading.
(Reporting by Ernest Scheyder; Editing by Andre Grenon and Grant McCool)