The Outer Continental Shelf (OCS) of the US Gulf of Mexico (GOM) is the most explored, drilled and extensively developed offshore petroleum province in the world. Since 1953 and up to 2000 inclusive, more than 35 thousand wells have been drilled offshore in GOM (including wells plugged and abandoned). Cumulative production of oil and gas to this date stands at 13 billion barrels of oil and 146 tcf of gas (9.7 per cent and 17.5 per cent, respectively, of cumulative US production to date since 1953). The prominence of this region as far as the US petroleum supply picture is concerned has grown markedly over the years, on the back of the output decline in traditional onshore basins (Figure F1.1). Currently, there are 39 million acres under lea...