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Finding gas and oil deposits at such depths is no easy technological feat. Seismologists in surface vessels bounce sonar-like signals off the bottom, and computers use the echoes to make three-dimensional tracings of rock formations likely to contain oil. To get at the deposits, explorers must lower a drill to the sea floor and then bore a hole 3 km (2 miles) or deeper through sands and shales. The gear has to be specially strengthened to withstand the high pressure and covered with fine metal screens to keep out sand. Drill-ship operators employ satellites and celestial navigation to take up a position precisely over the hole, and heavy thruster motors keep the vessel hovering there, even in heavy seas, for days at a time. Decks the size of football fields are needed to stack the thousands of meters of unusually tough steel pipe used to sink the shaft.
Bringing the oil to the surface and then through a pipeline to shore is an even more vexing challenge, requiring new construction design and logistical savvy. To get Shell's Bullwinkle platform into position took 12 tugboats and construction of the world's largest barge -- an aircraft-carrier-size hulk -- to haul it. But when the oil is at depths beyond 450 m (1,500 ft.), such fixed production facilities become too costly and complicated, forcing engineers to build floating platforms. Conoco's deepwater facility, called a tension-leg well platform, is tethered to pilings on the sea bottom by flexible strands of heavy, tubular steel.
Because divers cannot routinely work at these depths, oilmen have turned to mini-submarines and creations called ROVs (remotely operated vehicles) to install and maintain their rigs and platforms. An operator topside maneuvers aluminum ROVs by flashing signals through an umbilical tether containing ; fiberglass optical wire. TV cameras mounted on the ROVs send back pictures to the surface. To twist and turn the clawlike arms, technicians rotate pistol- grip levers, as in a video game. Says John Huff, president of Oceaneering International, which operates the vehicles: "ROVs have removed all the limits on how deep we can explore."
To keep costs and maintenance down, oil companies are ingeniously simplifying project designs. Conoco is doing only minimal processing of gas and oil at its new platform. Instead, the crude is routed through pipes on the bottom to a processing unit 16 km (10 miles) away in shallower waters. Exxon is investing $500 million in an elaborate subsea production system that will permit initial processing of gas from 22 wells directly on the sea floor. The gas will then flow to a larger facility atop an undersea mountain.