106 



Forecast services do an admirable job, but Nortli Sea weather changes so 

 often and so quickly that meteorologists simply can't always keep abreast of 

 develooments. 



Gales lash the sea all year. Vicious storms with hurricane-force winds are & 

 constant threat in fall and winter, and, when they hit, rig crews have no time 

 to do anything but ride them out. Fog, haze, almost constant cloud cover, and 

 frequent showers add to the headaches. 



Tides, which rise and fall 16-18 ft. in some places, sweep in and out each 

 614 hr. Divers are restricted to about 2 hr. of slack tide per day. The tides 

 give rise to currents — sometimes 2-4 knots — which often scour sand from 

 around drilling-platform legs. 



As expected, the cold in winter has not been too severe, and icing has not been 

 a problem. Winter temperatures hover in the low to mid-thirties (Fahrenheit), 

 while summer temperatures seldom get above 80° F. 



Rewriting records. Because the North Sea is so important to shipping, border 

 nations have taken weather forecasting seriously and keep good records that go 

 back several decades. From these records, oil companies developed an idea of 

 the worst likely wind and sea conditions that would occur once a century. These 

 data were the basis for initial designs of platforms and other installations. 



The first well off England put the design criteria to a quick test. A 100-year 

 storm struck the jackup Mr. Cap in early 1965 shortly after it moved to a Dogger 

 Bank location for Amoseas. Storm waves ran about 10% higher than expected. 



According to London Meteorological OflBce records, Mr. Cap's crew reported 

 waves of 40 ft from trough to crest. And the U.K. National Institute of Ocean- 

 ography estimated probably maximum waves were 45 ft high. 



Operating trcncU. Despite storms and shipping hazards, British operators 

 initially prefer fixed platforms for field development. After outlining their fields 

 with jackup or semisubmersible rigs, they in^-tall large, multiwell structures to 

 drill several directional exploitation wells. These platforms will be brightly 

 lighted, equipped with far-reaching foghorns, and precisely charted on naviga- 

 tional maps. 



Seven wells have been drilled with fioating rigs and subsea-wellhead equij)- 

 ment, but these have been abandoned. No operator yet sees a compelling need to 

 produce wells completed at the ocean floor. However, this view may change as 

 drilling progresses northward in the next few years where water depths increase 

 to 400-^50 ft. in some licensed areas. 



With jackup barges, most operators drill with caisson or mud-linewells can 

 be temporarily abandoned at the ocean floor and reentered later for either an 

 abovewater or underwater completion. 



Rig fleet grows. If all goes well with British price talks, North Sea activity 

 should surge ahead in coming months. 



British Petroleum will have two development rigs running on fixed platforms 

 in U.K. Block 48/6. Shell-Esso plan to install a rig and fixed platform to drill 10 

 development wells in U.K. Block 49/6 and will lay a 30-mile, 30-in. pipeline to 

 shore. 



Mobil Oil gets its first rig next month when North Sea Marine Engineering 

 delivers the Norsmec I jackup for drilling in British waters. Shell will start 

 drilling off England with its Stafio semisubmersible and hopes to take delivery 

 this year on a semisubmersible and a jackup from Sea Drilling Netherlands, a 

 new contract-drilling firm led by Southeastern Drilling. 



Dansk Underground Consortium (DUC) — composed of A. P. Moller, Shell, 

 Amoseas, and Gulf — will start drilling with its first full-time rig : a jackup owned 

 by Zapata Off-Shore and built in the U.S. 



Gulf Oil, operator for DUC, has ordered another jackup from a group of 

 drillers headed by Rimrock Tidelands and will use the unit in British waters. 



Ocean Drilling & Exploration's semisubmersible Ocean Viking, under contract 

 to Phillips, joins ODECO's Ocean Explorer, working for Esso, in Norwegian 

 waters. And Amoco plans to drill off Norway with a converted whaling vessel. 



These new additions should fairly well take care of commitments for the time 

 being — unless the Dutch finally get around to leasing their section of the North 

 Sea. Oil companies believe the odds are 50-50 that Holland will act this year. 



England's high success ratio plus the promise of important things to come in 

 the Dutch "fairway" add up to a more than even chance that the North Sea could 

 soon pass the threshold into the ranks of major producing areas. All the oil com- 

 panies ask is fair treatment so they can get on with providing the answer. 



