Shale oil production in the United States will decline in the long-term and reach its peak by 2020, the head of Russian state-run oil company Rosneft said on Wednesday. “Shale oil production has its limitations in scope and time,” Igor Sechin said at the IP Week conference. “U.S. shale oil production will reach its peak in 2020.” (Reporting by Ron Bousso and Dmitry Zhdannikov; editing by Jason Neely )