BP said Wednesday that it has drilled the world's deepest oil well in the Gulf of Mexico and found a giant pool of crude, a discovery that promises to make an indelible mark on the south Louisiana economy. The Tiber Prospect is expected to rank among the largest petroleum discoveries in the United States, potentially producing half as much crude in a day as Alaska's famous North Slope oil field. Louisiana energy circles were abuzz with news of the discovery Wednesday. "Any incremental business in the Gulf of Mexico is going to be a net positive for us one way...