Occidental Petroleum Corp. Chief Financial Officer Stephen Chazen will take on the additional role of president for the Los Angeles-based oil company.

Chazen will add oil and gas exploration to his duties, as well as corporate development, oil and natural-gas marketing, and chemicals. Chief Executive Ray Irani was previously in charge of oil and gas exploration and will remain as the company’s chief executive and chairman at least until 2015, when his contract expires.

Chazen, 61, joined Occidental in 1994 as an executive for corporate development and was named chief financial officer in 1999.

Shares in Occidental were down 1.9 percent to $71.81 in early trading Friday on the New York Stock Exchange.