National Geographic : 1972 Jun
More than $800 million in offshore royalties and lease bonuses has been paid annually to state and federal treasuries. To look for oil and gas at sea, our ex plorers use modifications of the tools they use for the search on shore. If early reconnaissance is encouraging, the search advances to seismic surveys. Shock waves are generated which travel downward, striking successive rock formations beneath the surface of the sea. These waves are re flected back to the surface where detecting devices record the impulses. By measuring the time intervals of the waves, a geophysi cist can tell the general characteristics of the formations that lie below the ocean floor. But he can't tell if the rocks contain oil and gas. Only a drill can do that. Our sleeve exploder. A few years ago, Esso Production Re search, a Jersey Standard affiliate, invented a device to replace the use of dynamite in offshore seismic work. It explodes a small gas charge in a heavy rubber sleeve, inflating it like an instant balloon and producing a seis mic echo. It provides more data in less time. It's a lot less expensive than dynamite. And it won't kill the fish. Bids in the $millions. Even if our geophysical and geological findings indicate a good chance of oil or natural gas under the ocean floor, drilling is still a long way off. Next, we must obtain the right to drill. There may be long public hearings or gov ernment studies prior to bidding for leases. In areas considered highly prospective, competitors for the leases can put hundreds of millions of dollars into public coffers. Oil companies must also pay royalties on every barrel of oil and every cubic foot of gas pro duced. In recent years, offshore lease bonuses and royalties paid to state and federal treasur ies have averaged over $800 million per year. Once a lease is granted, exploratory drilling can begin. But the odds are still against us. For every fifty wildcat wells drilled on land in the U.S., only one finds a field that will turn a profit. Because offshore areas are relatively unexplored, the odds of finding oil or gas at sea are better-but it's still a real long shot. If exploratory drilling finds oil or gas, fixed platforms to develop a field of wells are then put in place. They contain living quar ters for the work crew, a helicopter landing pad, storage space for supplies, and room for all the complicated drilling and production equipment. From these "islands," up to thirty wells can be drilled directionally to locations as far as a mile away. In the search for oil and gas at sea, we use three basic types of mobile drilling rigs. A) This self-elevating rig is towed to a site where its legs are lowered to the sea bed, and its platform "jacked up" above the water. Jack-up rigs are limited to waters up to 300 feet deep. Beyond this depth, floating rigs must be used. B) Semi-submersible rigs are supported by giganticbuoyant chambers, which are ballastedwith sea water and submerged. The drilling platform stays safely above the waves' reach. C) In very deep water, ships with large holes midship for drilling are used. D) After a discovery, fixed platforms are built to drill development wells and handleproduction.