scholarly journals Pockmark formation and activity, U.K. block 15/25, North Sea

1994 ◽  
Vol 41 ◽  
pp. 34-49
Author(s):  
Alan Judd ◽  
David Long ◽  
Michael Sankey
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
Petroleum Exploration ◽  
Gas Migration ◽  
The North ◽  
Pit Formation ◽  
The North Sea ◽  
Recent Sediments ◽  
Migration Pathways ◽  
Exploration Well

Digital seismic reflection (boomer) profiles of an active pockmark, in UK block 15/25, North Sea, reveal that the feature was formed prior to the deposition of the most recent sediments, probably by vigorous (or even catastrophic) gas escape. This release may have been triggered by the melting of ground ice when North Atlantic waters first entered the North Sea after the last glaciation, about 13,000 years ago. Possible sources of the gas are investigated by examining the composite log from a nearby petroleum exploration well; it is concluded that, although the gas may .originate from the Kimmeridge Clay, it probably comes from lignites of Tertiary age. Its migration towards the seabed is interrupted by local accumulations at several horizons, the shallowest of which (<80 m below seabed) is trapped beneath clayey sediments of the Coal Pit Formation. The topography of the base of this layer apparently controls the location of gas migration pathways to the seabed. As these lead to pockmarks which formed long ago, and as these pockmarks are still active today, it is probable that the migration pathways have remained throughout the intervening period. Gas accumulating beneath the Coal Pit Formation may migrate laterally to reach the pathways.

Temperature, Salinity and Plankton in the Eastern North Atlantic and Coastal Waters of Britain, 1957.: I. The Characterisation and Distribution of Surface Waters

1963 ◽  
Vol 20 (3) ◽  
pp. 789-826 ◽  
Author(s):  
B. McK. Bary
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
Coastal Waters ◽  
Water Bodies ◽  
English Channel ◽  
Oceanic Water ◽  
Climatic Fluctuations ◽  
The North ◽  
The North Sea ◽  
Eastern North Atlantic

Monthly temperature-salinity diagrams for 1957 have demonstrated that three surface oceanic "water bodies" were consistently present in the eastern North Atlantic; two are regarded as modified North Atlantic Central water which give rise to the third by mixing. As well in the oceanic areas, large and small, high or low salinity patches of water were common. Effects of seasonal climatic fluctuations differed in the several oceanic water bodies. In coastal waters, differences in properties and in seasonal and annual cycles of the properties distinguish the waters from the North Sea, English Channel and the western entrance to the Channel.The geographic distributions of the oceanic waters are consistent with "northern" and "southern" water bodies mixing to form a "transitional" water. Within this distribution there are short-term changes in boundaries and long-term (seasonal) changes in size of the water bodies.Water in the western approaches to the English Channel appeared to be influenced chiefly by the mixed, oceanic transitional water; oceanic influences in the North Sea appear to have been from northern and transitional waters.

scholarly journals Climate-Driven Change in the North Atlantic and Arctic Oceans Can Greatly Reduce the Circulation of the North Sea

2018 ◽  
Vol 45 (21) ◽  
pp. 11,827-11,836 ◽  
Author(s):  
Jason Holt ◽  
Jeff Polton ◽  
John Huthnance ◽  
Sarah Wakelin ◽  
Enda O'Dea ◽  
...  
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
The North ◽  
The North Sea ◽  
The North Atlantic

scholarly journals The carbon budget of the North Sea

2005 ◽  
Vol 2 (1) ◽  
pp. 87-96 ◽  
Author(s):  
H. Thomas ◽  
Y. Bozec ◽  
H. J. W. de Baar ◽  
K. Elkalay ◽  
M. Frankignoulle ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Continental Shelf ◽  
North Sea ◽  
North Atlantic ◽  
Carbon Budget ◽  
North Atlantic Ocean ◽  
Carbon Sink ◽  
The North ◽  
The North Sea ◽  
The North Atlantic

Abstract. A carbon budget has been established for the North Sea, a shelf sea on the NW European continental shelf. The carbon exchange fluxes with the North Atlantic Ocean dominate the gross carbon budget. The net carbon budget – more relevant to the issue of the contribution of the coastal ocean to the marine carbon cycle – is dominated by the carbon inputs from rivers, the Baltic Sea and the atmosphere. The North Sea acts as a sink for organic carbon and thus can be characterised as a heterotrophic system. The dominant carbon sink is the final export to the North Atlantic Ocean. More than 90% of the CO2 taken up from the atmosphere is exported to the North Atlantic Ocean making the North Sea a highly efficient continental shelf pump for carbon.

scholarly journals North Atlantic storm driving of extreme wave heights in the North Sea

2017 ◽  
Vol 122 (4) ◽  
pp. 3253-3268 ◽  
Author(s):  
R. J. Bell ◽  
S. L. Gray ◽  
O. P. Jones
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
Extreme Wave ◽  
The North ◽  
Wave Heights ◽  
The North Sea

scholarly journals Synchronous ecological regime shifts in the central Baltic and the North Sea in the late 1980s

2005 ◽  
Vol 62 (7) ◽  
pp. 1205-1215 ◽  
Author(s):  
J. Alheit ◽  
C. Möllmann ◽  
J. Dutz ◽  
G. Kornilovs ◽  
P. Loewe ◽  
...  
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
Climatic Variability ◽  
Regime Shifts ◽  
Trophic Levels ◽  
Copepod Species ◽  
The North ◽  
The North Sea ◽  
The North Atlantic ◽  
Low Levels

Abstract The index of the North Atlantic Oscillation, the dominant mode of climatic variability in the North Atlantic region, changed in the late 1980s (1987–1989) from a negative to a positive phase. This led to regime shifts in the ecology of the North Sea (NS) and the central Baltic Sea (CBS), which involved all trophic levels in the pelagial of these two neighbouring continental shelf seas. Increasing air and sea surface temperatures, which affected critical physical and biological processes, were the main direct and indirect driving forces. After 1987, phytoplankton biomass in both systems increased and the growing season was extended. The composition of phyto- and zooplankton communities in both seas changed conspicuously, e.g. dinoflagellate abundance increased and diatom abundance decreased in the CBS. Key copepod species that are essential in fish diets experienced pronounced changes in biomass. Abundance of Calanus finmarchicus (NS) and Pseudocalanus sp. (CBS) fell to low levels, whereas C. helgolandicus (NS) and Temora longicornis and Acartia spp. (CBS) were persistently abundant. These changes in biomass of different copepod species had dramatic consequences on biomass, fisheries, and landings of key fish species: North Sea cod declined, cod in the CBS remained at low levels, and CBS sprat reached unprecedented high biomass levels resulting in high yields. The synchronous regime shifts in NS and CBS resulted in profound changes in both marine ecosystems. However, the reaction of fish populations to the bottom-up mechanisms caused by the same climatic shift was very different for the three fish stocks.

Design, Drilling, and Testing of a Deviated HTHP Exploration Well in the North Sea

1994 ◽  
Vol 9 (04) ◽  
pp. 244-248 ◽  
Author(s):  
K.P. Seymour ◽  
Robert MacAndrew
Keyword(s):  
North Sea ◽  
The North ◽  
The North Sea ◽  
Exploration Well
Sign in / Sign up

Export Citation Format

Share Document