An evaluation of seismic and borehole data available from onshore and offshore site investigations of relict glaciated areas

1991 ◽  
Vol 7 (1) ◽  
pp. 573-578 ◽  
Author(s):  
F. S. Stewart
Keyword(s):  
North Sea ◽  
Structural Information ◽  
Late Quaternary ◽  
Seismic Survey ◽  
Borehole Data ◽  
The North ◽  
Site Investigations ◽  
The North Sea ◽  
Engineering Projects ◽  
Sedimentation Processes

AbstractUsing late Quaternary ice marginal sites from the North Sea and Iceland a comparison of the sedimentary information available from subaerial and submarine site investigations was made. This was with regard to palaeo-environmental reconstructions of ice marginal Sedimentation processes. A detailed high resolution seismic survey in-the North Sea was compared to a similar subaerial site in Iceland. Submarine cores were compared with logged sections available from cliffs. These comparisons highlighted the differences in resolution of the structural information available and also the problems of applying existing modeis of glacimarine Sedimentation to offshore sites. This has raised questions concerning the accuracy of reconstructing palaeo-environments and processes in offshore sites presently under investigation. The implications of this for engineering projects in offshore areas requiring very precise site information about relict glaciated areas are significant.

scholarly journals Geological evolution of the Chalk Group in the northern Dutch North Sea: inversion, sedimentation and redeposition

2018 ◽  
Vol 156 (07) ◽  
pp. 1265-1284
Author(s):  
EVA VAN DER VOET ◽  
LEONORA HEIJNEN ◽  
JOHN J. G. REIJMER
Keyword(s):  
North Sea ◽  
Late Cretaceous ◽  
Seismic Survey ◽  
Structural Elements ◽  
The North ◽  
Show Evidence ◽  
New Finding ◽  
The North Sea ◽  
Thickness Variations ◽  
Well Data

AbstractIn contrast to the Norwegian and Danish sectors, where significant hydrocarbon reserves were found in chalk reservoirs, limited studies exist analysing the chalk evolution in the Dutch part of the North Sea. To provide a better understanding of this evolution, a tectono-sedimentary study of the Late Cretaceous to Early Palaeogene Chalk Group in the northern Dutch North Sea was performed, facilitated by a relatively new 3D seismic survey. Integrating seismic and biostratigraphic well data, seven chronostratigraphic units were mapped, allowing a reconstruction of intra-chalk geological events.The southwestward thickening of the Turonian sequence is interpreted to result from tilting, and the absence of Coniacian and Santonian sediments in the western part of the study area is probably the result of non-deposition. Seismic truncations show evidence of a widespread inversion phase, the timing of which differs between the structural elements. It started at the end of the Campanian followed by a second pulse during the Maastrichtian, a new finding not reported before. After subsidence during the Maastrichtian and Danian, renewed inversion and erosion occurred at the end of the Danian. Halokinesis processes resulted in thickness variations of chalk units of different ages.In summary, variations in sedimentation patterns in the northern Dutch North Sea relate to the Sub-Hercynian inversion phase during the Campanian and Maastrichtian, the Laramide inversion phase at the end of the Danian, and halokinesis processes. Additionally, the Late Cretaceous sea floor was characterized by erosion through contour bottom currents at different scales and resedimentation by slope failures.

scholarly journals Hydrogeological characterisation of a glacially affected barrier island – the North Frisian Island of Föhr

2012 ◽  
Vol 9 (4) ◽  
pp. 5085-5119 ◽  
Author(s):  
T. Burschil ◽  
W. Scheer ◽  
R. Kirsch ◽  
H. Wiederhold
Keyword(s):  
North Sea ◽  
Underground Structure ◽  
Empirical Relation ◽  
Geophysical Methods ◽  
Strong Impact ◽  
Hydrogeological Model ◽  
Borehole Data ◽  
The North ◽  
The North Sea ◽  
D Model

Abstract. We present the application of geophysical investigations to characterise and improve the geological/hydrogeological model through the estimation of petrophysical parameters for groundwater modelling. Seismic reflection and airborne electromagnetic surveys in combination with borehole information enhance the 3-D geological model and allow a petrophysical interpretation of the subsurface. The North Sea Island of Föhr has a very complex underground structure what was already known from boreholes. The local waterworks use a freshwater body embedded in saline groundwater. Several glaciations disordered the Youngest Tertiary and Quaternary sediments by glaciotectonic thrust-faulting as well as incision and refill of glacial valleys. Both underground structures have a strong impact on the distribution of freshwater bearing aquifers. An initial hydrogeological model of Föhr was built from borehole data alone and was restricted to the southern part of the island where in the sandy areas of the Geest a large freshwater body was formed. We improved the geological/hydrogeological model by adding data from different geophysical methods, e.g. airborne electromagnetics (EM) for mapping the resistivity of the entire island, seismic reflections for detailed cross sections in the groundwater catchment area, and geophysical borehole logging for calibration of these measurements. An integrated evaluation of the results from the different geophysical methods yields reliable data. To determinate petrophysical parameter about 18 borehole logs, more than 75 m deep, and nearby airborne EM inversion models were analyzed concerning resistivity. We establish an empirical relation between measured resistivity and hydraulic conductivity for the specific area – the North Sea island of Föhr. Five boreholes concerning seismic interval velocities discriminate sand and till. The interpretation of these data was the basis for building the geological/hydrogeological 3-D model. We fitted the relevant model layers to all geophysical and geological data and created a consistent 3-D model. This model is the fundament for groundwater simulations considering forecasted changes in precipitation and sea level rise due to climate change.

A late Quaternary bio- and climatostratigraphy for marine sediments in the north-central part of the North Sea

Boreas ◽  
2008 ◽  
Vol 7 (2) ◽  
pp. 91-96 ◽  
Author(s):  
REX HARLAND ◽  
DIANE M. GREGORY ◽  
MURRAY J. HUGHES ◽  
IAN P. WILKINSON
Keyword(s):  
North Sea ◽  
Marine Sediments ◽  
Late Quaternary ◽  
North Central ◽  
The North ◽  
The North Sea

Case history of a six‐streamer seismic survey in the North Sea

1991 ◽  
Author(s):  
Gary Hampson ◽  
Terje Hansen ◽  
H. Jakubowicz ◽  
John V. Kingston
Keyword(s):  
North Sea ◽  
Case History ◽  
Seismic Survey ◽  
The North ◽  
History Of ◽  
The North Sea

High-resolution reservoir characterization by an acoustic impedance inversion of a Tertiary deltaic clinoform system in the North Sea

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. O57-O67 ◽  
Author(s):  
Daria Tetyukhina ◽  
Lucas J. van Vliet ◽  
Stefan M. Luthi ◽  
Kees Wapenaar
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Reservoir Characterization ◽  
Structural Information ◽  
Sampling Rate ◽  
Seismic Inversion ◽  
Acoustic Properties ◽  
The North ◽  
The North Sea ◽  
Well Data

Fluvio-deltaic sedimentary systems are of great interest for explorationists because they can form prolific hydrocarbon plays. However, they are also among the most complex and heterogeneous ones encountered in the subsurface, and potential reservoir units are often close to or below seismic resolution. For seismic inversion, it is therefore important to integrate the seismic data with higher resolution constraints obtained from well logs, whereby not only the acoustic properties are used but also the detailed layering characteristics. We have applied two inversion approaches for poststack, time-migrated seismic data to a clinoform sequence in the North Sea. Both methods are recursive trace-based techniques that use well data as a priori constraints but differ in the way they incorporate structural information. One method uses a discrete layer model from the well that is propagated laterally along the clinoform layers, which are modeled as sigmoids. The second method uses a constant sampling rate from the well data and uses horizontal and vertical regularization parameters for lateral propagation. The first method has a low level of parameterization embedded in a geologic framework and is computationally fast. The second method has a much higher degree of parameterization but is flexible enough to detect deviations in the geologic settings of the reservoir; however, there is no explicit geologic significance and the method is computationally much less efficient. Forward seismic modeling of the two inversion results indicates a good match of both methods with the actual seismic data.

scholarly journals Multi-Proxy Characterisation of the Storegga Tsunami and Its Impact on the Early Holocene Landscapes of the Southern North Sea

Geosciences ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 270 ◽  
Author(s):  
Vincent Gaffney ◽  
Simon Fitch ◽  
Martin Bates ◽  
Roselyn L. Ware ◽  
Tim Kinnaird ◽  
...  
Keyword(s):  
North Sea ◽  
River System ◽  
Seismic Survey ◽  
Tsunami Deposit ◽  
Southern North Sea ◽  
The North ◽  
Sediment Deposits ◽  
The North Sea ◽  
Northern North Sea ◽  
The Impact

Doggerland was a landmass occupying an area currently covered by the North Sea until marine inundation took place during the mid-Holocene, ultimately separating the British landmass from the rest of Europe. The Storegga Event, which triggered a tsunami reflected in sediment deposits in the northern North Sea, northeast coastlines of the British Isles and across the North Atlantic, was a major event during this transgressive phase. The spatial extent of the Storegga tsunami however remains unconfirmed as, to date, no direct evidence for the event has been recovered from the southern North Sea. We present evidence of a tsunami deposit in the southern North Sea at the head of a palaeo-river system that has been identified using seismic survey. The evidence, based on lithostratigraphy, geochemical signatures, macro and microfossils and sedimentary ancient DNA (sedaDNA), supported by optical stimulated luminescence (OSL) and radiocarbon dating, suggests that these deposits were a result of the tsunami. Seismic identification of this stratum and analysis of adjacent cores showed diminished traces of the tsunami which was largely removed by subsequent erosional processes. Our results confirm previous modelling of the impact of the tsunami within this area of the southern North Sea, and also indicate that these effects were temporary, localized, and mitigated by the dense woodland and topography of the area. We conclude that clear physical remnants of the wave in these areas are likely to be restricted to now buried, palaeo-inland basins and incised river valley systems.

Repeated Seismic Survey From the North Sea using New Streamer Technology

2000 ◽  
Author(s):  
Ola Eiken ◽  
Morten Svendsen ◽  
Torstein Navrestad ◽  
Erik Haavarstein ◽  
Leif Larsen
Keyword(s):  
North Sea ◽  
Seismic Survey ◽  
The North ◽  
The North Sea

The identification of features due to former permafrost in the North Sea

1991 ◽  
Vol 7 (1) ◽  
pp. 369-372 ◽  
Author(s):  
D. Long
Keyword(s):  
North Sea ◽  
The North ◽  
Site Investigations ◽  
The North Sea ◽  
Marine Data

AbstractAnalysis of offshore data at scales varing from macroscopic to kilometric suggest the former presence of permafrost in the North Sea. However due to the nature of marine data, the techniques used in recognizing features due to former permafrost differ from that used on land. The evidence can also occur in forms unique to the marine field. Awareness of the former existence of permafrost in the North Sea will aid geological assessment of offshore site investigations.

scholarly journals THREE-DIMENSIONAL MARINE MODELS FOR IMPACT STUDIES

1982 ◽  
Vol 1 (18) ◽  
pp. 47 ◽  
Author(s):  
Jacques C.J. Nihoul ◽  
Francois C. Ronday
Keyword(s):  
North Sea ◽  
Hydrodynamic Model ◽  
Three Dimensional ◽  
Storm Surges ◽  
Coastal Engineering ◽  
The North ◽  
The North Sea ◽  
The Impact ◽  
Engineering Projects

A three-dimensional non-linear hydrodynamic model is developed for the determination of the mesoscale (tides, storm surges, ...) and macroscale (residuals, gyre, ...) circulations in the North Sea. The model consists of a hierarchy of submodels of different grid sizes, with interactive coupling at boundaries. The model is used to study the impact of coastal engineering projects along the Belgian coast and in the Scheldt estuary.

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