At Exxon's U.S. Gulf Coast refineries, "We have more than tripled the processing of (cheaper) North American crude over the last couple of years," the company's vice president of investor relations, David Rosenthal, told analysts on a conference call. He declined to give precise figures or percentages.
Irving, Texas-based Exxon Mobil said it spent $5 billion during the quarter buying back its own shares and plans to spend another $5 billion on buybacks in the first three months of 2013.
Exxon shares rose 7 cents to close at $90.04 Friday. They gained 4 percent in January.
Chevron Corp., the No. 2 U.S. oil company, reported that fourth-quarter net income rose 41 percent to $7.23 billion. That result was helped by a gain of $1.4 billion related to an exchange of assets in Australia.