One of Africa’s biggest oil producers, Angola, will sign next week an exclusive agreement with Shell under which the supermajor will explore and potentially develop several offshore blocks, Angola’s oil and gas agency ANPG has said. “This event marks a historic moment for the Angolan oil sector, consolidating Shell's presence in Angola, an ANPG statement said, as carried by Reuters. Under the agreement Shell will explore Blocks 19, 34, and 35 and several ultra-deepwater blocks as Angola looks to revive its exploration and…