Exploring The Ocean's Frontiers

By RICHARD WOODBURY NEW ORLEANS

The dark and forbidding depths of the Gulf of Mexico, once frequented by only the hardiest of sea creatures, are now alive with human activity. Miniature submarines and robot-like vehicles prowl the ocean bottom while divers wend their way around incredible underwater structures -- taller than Manhattan skyscrapers but almost totally beneath the surface of the waves. This is the new geological frontier, and a daring breed of modern-day explorers is using technology worthy of Jules Verne and Jacques Cousteau to find fresh supplies of oil and natural gas.

Until recently, drilling in the Gulf was concentrated close to shore in water as shallow as 9 m (30 ft.). But now that most of those easy-to-tap reserves are depleted, oilmen are looking to the slopes of the continental shelf, hundreds of meters deep and 160 km (100 miles) or more from land. The cutoff of oil supplies from Kuwait and Iraq and the resulting run-up in prices have lent new urgency to the exploration ventures, some of which have been in the works for a few years. "Oil at $30 to $40 a barrel is suddenly making every project that boosts our domestic supplies look a lot more feasible," says Wayne Dunlap, an offshore technology expert at Texas A&M.

Led by Conoco, Occidental, Texaco and Shell, every major international oil company has joined the hunt, which has turned the blue-green waters off the coast of Louisiana and Texas into one of the busiest exploration areas in North America. Even Petrobras, the national oil company of Brazil and a deep- drilling pioneer, has established a Houston-based subsidiary to get in on the action. The lure of the Gulf is irresistible: estimated oil reserves of up to 36 billion bbl., nearly four times as much as in Alaska's Prudhoe Bay. Companies have snapped up nearly 1,700 federal drilling leases at depths of 370 m (1,200 ft.) and beyond. Some 25 rigs are currently in operation, and several big production projects are in the works.

The far reaches of the Gulf are especially attractive to the major companies because there has been little of the environmental opposition that has blocked most drilling efforts off California and the East Coast. The oil industry is a major employer along the Gulf, and coastal residents have lived with drilling just offshore since 1947.

The deepwater quest began in 1984, when the Hunt brothers pioneered some of the new production techniques in a subterranean formation known as Green Canyon, some 240 km (150 miles) southwest of New Orleans. But they failed to make the big strike they needed to salvage their collapsing financial empire. Conoco followed the Hunts and had more luck, finding sizable deposits at the * 535-m (1,760-ft.) level. The company, with Occidental and Texaco, spent $400 million to build the world's deepest production platform, and has been producing from 20 wells for about a year.

An equally huge project is Shell's $500 million Bullwinkle platform, 130 km (80 miles) off the Louisiana coast. Standing 162 stories high -- taller by 49 m (161 ft.) than Chicago's Sears Tower -- it looms like a gigantic iceberg in 412 m (1,353 ft.) of water, only its top-deck production facilities visible above the water. Chevron is planning a big project nearby. Southeast of New Orleans, Exxon is operating a 110-story platform, and a few miles away British Petroleum is erecting its own 100-story behemoth.

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.

The current projects are only the beginning. "The real potential lies farther and deeper offshore," says Roger Abel, Conoco's general manager for production engineering. "The big easies have all been found." Shell is investing $1.3 billion to build and install a tension-leg platform some 411 km (255 miles) southeast of Houston that will retrieve oil from a world-record depth of 872 m (2,860 ft.). Called Auger, the giant is scheduled to begin producing from 32 wells in 1993. Shell has also drilled an exploratory well at a 2,300-m (7,500-ft.) depth, and Mobil and Chevron hold leases to search in 3,000 m (10,000 ft.) of water. As long as oil prices make the gamble worthwhile, today's explorers will apparently go to any depths to unleash the next great undersea gusher.