MADRID - Spanish oil firm Repsol YPF SA has begun offshore drilling in Cuban waters as part of its global exploration operations, a person familiar with the situation said Thursday. Deep-water exploration drilling began about 50 kilometers north of Havana and will take at least 60 days to complete, this person added. Repsol is resuming exploration in the area after it failed to find exploitable oil in 2004. The U.S. Geological Survey has said there could be a substantial amount of untapped oil off the Cuban coast. The Repsol well is much closer to Florida than any other well in...