Exploration and production (E&P) in deep water (500-2000 m [1640-6560 ft]) and ultra-deep-water (>2000 m [>6560 ft]) settings have expanded greatly during the past 20 years, to the point at which they are now major components of the petroleum industry’s upstream budgets. Most exploration and production activity has concentrated in only three areas of the world: the northern Gulf of Mexico, offshore Brazil, and offshore West Africa, although activity is increasing in several new areas. Globally, deep water remains an immature frontier, with many deep-water sedimentary basins being only lightly explored. Although deep-water discoveries account for less than 5% of the current worldwide oil-equivalent resources, the amount is increasing rapidly. Importantly, these resources are primarily oil; gas exploration is immature, reflecting infrastructure and economic limitations. There have been at least 42 giant fields (>500 million BOE) discovered in deep water.

By year end 2003, approximately 78 billion BOE of total resources had been discovered in deep water from 18 basins on six continents. This total consists of 48 BBO and condensate and 174 TCFG. Deep water contains 85% of the reserves and ultra-deep water has 15%. The immaturity of the play is illustrated by the fact that >50% of the reserves have been discovered since 1995, with 31% being developed and 5% produced. The exploration success ratio, particularly in basins such as the northern Gulf of Mexico and offshore West Africa, has been increasing. Most of these successes are in settings with younger (Cenozoic, mostly Neogene) sandstone reservoirs with direct