Chevron and Helleniq Energy signed leases Monday to explore for natural gas in four deep-water blocks off Greece, covering 47,000 square kilometers. Chevron shares last closed up 0.73% at $183.74 on Friday, with U.S. markets shut Monday for Presidents Day. Oil prices rose, with Brent settling at $68.65 a barrel. Investors await U.S.-Iran talks Tuesday and an OPEC+ policy meeting March 1.