There's an interesting article in the NY Times about the evolution of oil exploration in the Gulf of Mexico. The article focuses on the role that salt deposits play in trapping the oil. Salt deposits are cool things - given the right circumstances salt will flow and form domes, pillars (called diapirs), basins, or other structures. These can trap oil contained in adjacent permeable strata. Spindletop, the first highly productive oil field in Texas, is a salt dome with oil trapped beneath it. The photo is the famous Lucas well, which was the first to tap into the Spindletop reserves.
The NY Times article makes it clear that oil exploration in the Gulf is going to be with us for a long time. I hope we can figure out how to do it safely.