Northern North Sea

Steel piled jackets are the most common type of platform and are employed in a wide range of sea conditions, from the comparative calm of the South China Sea to the hostile Northern North Sea. Steel jackets are used in water depths of up to 150 metres and may support production facilities a further 50 metres above mean sea level. In deep water all the process and support facilities are normally supported on a single jacket, but in shallow seas it may be cheaper and safer to support drilling, production... 

Natural gas as distributed in the UK is obtained from various sources. These comprise primarily the southern North Sea basin, northern North Sea fields (both British and Norwegian), Morecambe Bay from the Irish Sea (used primarily for winter peaks) and gas from world sources imported in small quantities as liquefied natural gas (TNG). Gas from the different fields is of very consistent quality, and further blending, conditioning, etc. allows a gas of very consistent quality and specification to be distributed. 

Murray CN, Kautsky H, Hoppenheit M, et al. 1978. Actinide activities in water entering the northern North Sea. Nature 276 225-230. 

Oehme, M., et al. (1993). The ultra trace analysis of polychlorinated dibenzop-dioxins and diben-zofurans in sediments from the Arctic (Barents Sea) and Northern North Sea. Methodology and quality assurance. Analytical methods and instrumentation, 1, 153-163. 

In the North Sea the pipeline surroundings will be at sea bottom temperature, so we are Interested in minimum temperatures at that location. Surprisingly, in the deeper water (250 ) of the northern North Sea areas which are affected by the Gulf Stream, the minimum sea bottom temperatures may be as high as 46 to 48°F. In southern North Sea areas which are less affected by the Gulf Stream and also may be shallower, with bottom temperatures more influenced by wave action, we can expect minimums of 40°F or less. Only in very shallow waters near shore can we expect minimum temperatures approaching 32 F. 

Gieskes, W.W.C. and Kraay, G.W., 1980. Primary productivity and phytoplankton pigment measurements in the northern North Sea during FLEX 76. "Meteor" Forschung-sergebnisse, Reihe A., n° 22 105-112. 

Martin JHA, Hall WB (1975) Changes in physical, chemical and phytoplankton parameters in the northern North Sea, 1961-1970. ICES, CM 1975/C 33 l-4 Otto L, Zimmermann JTF, Furnes GK, Mork M, Saetre R, Becker G (1990) Review of physical oceanography of the North Sea. Neth J Sea Res 26 161-238 Owens NJP, Cook D, Colebrook M, Hunt H, Reid PC (1989) Long-term trends in the occurrence of Phaeo-cystis sp. In the North-East Atlantic Ocean. J Mar Biol Ass UK 69 813-821... 

Archer SD, Smith GC, Nightingale PD, Widdicombe CE, Tarran GA, Rees AP, Burkill PH (2002) Dynamics of particulate dimethylsulphoniopropionate during a Lagrangian experiment in the northern North Sea. Deep-Sea Res Part II 49 2979-2999... 

Hatton AD (2002a) Influence of photochemistry on the marine biogeochemical cycle of dimethylsulphide in the northern North Sea. Deep-Sea Res Part II 49 3039-3052 Hatton AD (2002b) DMSP removal and DMSO production in sedimenting particulate matter in the northern North Sea. Deep-Sea Res Part II 49 3053-3065 Hatton AD, Darroch L, Malin G (2004) The role of dim-ethylsulphoxide in the marine biogeochemical cycle of dimethylsulphide. Oceanogr Mar Biol Ann Rev 42 29-55 Hill RW, White BA, Cottrell MT, Dacey JWH (1998) Virus-mediated total release of dimethylsulfoniopropionate from marine phytoplankton a potential climate process. Aquat Microb Ecol 14 1-6... 

TCPM is reported in samples from areas from all over the world. A reason for this ubiquitous occurrence may be the presence of the 4-chlorophenyl rings in the compound, which are also found in p,p -DDT and its metabolites p,p -DDD and p,p -DDE, which are also very persistent contaminants. This structure is also found in bis(4-chlorophenyl) sulfone, which was recently reported as a new persistent contaminant [14]. The 4-chlorophenyl structure is apparently very resistant to transformation in the environment. Only in Mediterranean fish samples were TCPM and TCPMe not detected at a level of 1 pg/kg lipid weight. TCPM concentrations on a lipid weight basis decrease from 180 pg/kg to 360 pg/kg in eel from the river Rhine delta, to 40 pg/kg in cod liver from the southern North Sea, and to 6 pg/kg in cod liver from the northern North Sea (Table 2). This suggests a relationship between high TCPM concentrations and densely populated, industrialized areas. High TCPM concentrations in samples from the Baltic Sea and Lake Ontario and low TCPM concentrations in samples from Antarctica confirm this hypothesis. 

Hatton, A. D. (2002). Influence of photochemistry on the marine biogeochemical cycle of dimethyl-sulphide in the northern North Sea. Deep Sea Res. 49, 3039—3052. 

Helffrich G., Asencio E., Knapp J., and Owens T. (2003) Transition zone structure under the northern North Sea. Geophys. J. Int. (in press). 

L0n0y A., Akelson J., and Rpnning K. (1986) Diagenesis of a deeply buried sandstone reservoir, Hild Field, northern North Sea. Clay Min. 21, 497-511. 

Macaulay C. I., Fallick A. E., McLaughlin O. M., Haszeldine R. S., and Person M. J. (1998) The significance of dl3C of carbonate cements in reservoir sandstones a regional perspective from the Jurassic of the northern North Sea. In Carbonate Cementation in Sandstones (ed. S. Morad). International Association of Sedimentologists, Oxford, vol. 26,pp. 395-408. 

Pearson M. J. and Small J. S. (1988) Illite-smectite diagenesis and paleotemperature in northern North Sea Quaternary to Mesozoic shale sequence. Clay Min. 23, 109-132. 

Walderhaug O. (2000) Modeling quartz cementation and porosity in Middle Jurassic Brent Group sandstones of the Kvitebjorn Field, northern North Sea. Am. Assoc. Petrol. Geologists Bull. 84, 1325-1339. 

Barnard, P.C. and M.A. Bastow, 1991. Hydrocarbon generation, migration, alteration, entrapment and mixing in the Central and Northern North Sea. In England, W.A. and Fleet, A.J. (eds.). Petroleum migration. Geological Society Special Publication, no. 59, pp. 167-190... 

Gabrielsen, R.H. and Koestler, A.G. 1987. Description and structural implications of fractures in late Jurassic sandstones of the Troll Field, northern North Sea. Norsk Geol. Tidsskr. 67 371-381,... 

Nybakken, S. 1991. Sealing fault traps - an exploration concept in a mature petroleum province Tampen Spur, northern North Sea. First Break, 9 209-222. 

Fig. 6. Relationship of the regional maximum horizontal stress direction to the proportion of intra-reservoir sealing faults in any direction in the Northern North Sea.

It may be prudent to consider the possible influence of small shear displacements on faults brought about by mild reactivation or slip related to differential compaction. The Jurassic syn-rift conditions can be inferred to be favourable to clay smear formation, so it is appropriate to evaluate the probable response to burial and to at least minor shear displacement of clay smears in the northern North Sea. Here we resort only to field observations for this purpose. In cores taken in the NOCS, we have observed networks of closely spaced fractures in shale within faults which we would interpret as sometimes representing shear displacements measured in centimetres or even less. At the outcrop scale, Airo Farulla and Valore (1993) and others have described tectonized clay as composed of small, hard, tightly interlocked fragments or scales . This is clearly a discontinuum but with very closely spaced fractures. 

Increase in HCOj concentrations due to the degradation of oil by incurred meteoric waters. This is evidenced by carbonate cementation along the oil-water surface, such as in Tertiary, turbiditic reservoir sandstones from northern North Sea (Watson et al., 1995). 

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