Companies gambling there's oil in buried reef 



Massive steel rigs loom like vultures 

 over the Texas landscape, Alaska's 

 Prudhoe Bay and California's Santa 

 Barbara coastline drawing up long sips 

 of black crude to quench a nation's 

 powerful thirst for petroleum — oil that 

 is, black gold, Texas tea. Most of 

 America runs on oil and its 

 byproducts. Over one-third of that oil 

 is produced by foreign nations, many 

 of which are politically unstable. And 

 dwindling reserves of domestic oil and 

 gas are sending companies in search of 

 new frontiers for exploration. North 

 Carolina's outer continental shelf 

 holds the promise of being a new fron- 

 tier. 



Angela Waldorf, associate director 

 of the North Carolina Petroleum 

 Council, says the chances for finding 

 commercial quantities of oil and gas 

 are about one out of 50 in a wildcat 

 area such as North Carolina's outer 

 continental shelf, where no test wells 

 have been drilled. Several of the na- 

 tion's leading oil companies feel the 

 odds are good enough, though, and 

 they are plunking down millions for 

 leases on the nine-square-mile tracts, 

 and may spend millions more for ex- 

 ploration. Chevron USA Inc., the U.S. 

 Subsidary of Standard Oil of Califor- 

 nia, is the first in line to drill. Chevron 

 bought in on 12 tracts during Lease 



Photo by Simon Griffiths 



Stan Riggs 



Sale 56 held in August 1981. And R.L. 

 (Bob) Woodard, Chevron's division 

 exploration manager for the northern 

 division, says the company hopes to 

 begin drilling in 1983 on a tract off the 

 northern North Carolina coast. 



Secretary of Interior James Watt 

 wants to hasten the exploration and 

 development of oil and gas reserves 

 along the nation's outer continental 

 shelf. He has sped up the leasing 

 process and has sometimes sold leases 

 at bargain-basement prices (that's in 

 oil company scale-of-economy where a 

 few hundred thousand dollars for a 

 lease is cheap) to lure oil companies to 

 the shelf, where it is estimated that 25 

 to 33 percent of the undiscovered 

 reserves of oil and gas in the U.S. are 

 waiting. 



The bait luring oil companies like 

 Chevron, Atlantic Richfield and Gulf 

 to North Carolina's outer continental 

 shelf is about 190 million years old. It's 

 an elongated basin off the North and 

 South Carolina coasts that geologists 

 call the Carolina Trough. But it's not 

 the trough itself that has the oil com- 

 panies bidding millions of dollars for 

 leases. Stan Riggs, an East Carolina 

 University geologist and UNC Sea 

 Grant researcher, says it's the features 

 within the trough, a Jurassic reef and 

 salt domes or diapirs. 



Riggs says four ingredients are 

 needed to produce oil or gas. The first 

 and main ingredient is organic 

 material — dead plants and organisms. 

 Then the organics must be trans- 

 formed or cooked into oils and gases by 

 the right temperatures and pressures. 

 The wrong combination of tem- 

 perature and pressure could mean coal 

 instead of oil. Once formed, the oils 

 and gases need to be able to migrate 

 through porous sediments to reservoirs 

 or holding rocks where they are trap- 

 ped and held. 



Geologists believe the trough, 

 created during the rifting and 

 stretching that occurred as Africa and 

 North America . split during the 

 Triassic period, may have made a 

 suitable caldron for oil and gas. Ap- 

 proximately 39,000 feet of sediments 

 have accumulated in the trough, 

 leading geologists to believe adequate 

 pressures were present for the cooking. 

 The mounting sediments may have 

 also been heavy enough and permeable 



Photo courtesy of American Petroleum Institute 



Drilling in Alaska's Prudhoe Bay 



enough to squeeze the oil and gas from 

 the trough into nearby storage struc- 

 tures such as the Jurassic reef. 



Old coral reefs are particularly good 

 sites for oil and gas exploration. When 

 alive the reefs were prime collection 

 points for large amounts of organic 

 matter. And as they died and sank un- 

 der the weight of accumulating sedi- 

 ments, the reefs made excellent storage 

 bins. Their grainy makeup creates 

 plenty of pores for the oil and gas to 

 collect in, says Riggs. 



But the reef must be sealed if the 

 hydrocarbons are to remain trapped. 

 The Jurassic reef off North Carolina is 

 capped with fine-grain limestone 

 capable of sealing in oil and gas. 



Other geologic structures of interest 

 along the shelf are 21 salt domes or 

 diapirs found seaward of the Jurassic 

 reef. Salt domes in the Gulf of Mexico 

 have yielded large quantities of oil. 

 The salt domes, like the reefs, are 

 collection and storage areas. But 

 Waldorf says oil company interest, for 

 now at least, is in the reef and not the 

 domes. 



Geologists such as Riggs and Barry 

 Drucker, a staff geologist with the U.S. 

 Department of Interior's Minerals 

 Management Service, believe the reef 

 offers the best possibility for oil ex- 

 ploration along the East Coast. But no 



