Evaporite controls on basin-inversion structures in the southern Danish Central Graben, North Sea – a 3D seismic-data study

2020 ◽  
Author(s):  
Torsten Hundebøl Hansen ◽  
Ole Rønø Clausen
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Hydrocarbon Reservoirs ◽  
3D Seismic ◽  
Basin Inversion ◽  
The North ◽  
Basement Faults ◽  
Permian Salt ◽  
Southwestern Margin ◽  
3D Seismic Data

<p>During Cretaceous and Paleogene times, tectonic shortening caused mild basin inversion of earlier rifting depocentres in the Danish Central Graben. This exerted an important control on the thickness variations and geometries of e.g. the Late-Cretaceous and Danian Chalk Group. Structural highs formed by inversion and especially Permian-salt movements, host important hydrocarbon reservoirs in the sector. Earlier researchers have linked basin inversion in the North-Sea area to Alpine deformational phases and the onset of seafloor spreading in the North Atlantic.</p><p>The objective of this 3D seismic-data study is an analysis of the relationships between basement (sub-salt) faults, salt movements, and salt-cover deformation, as well as fluid migration near and within inversion structures.</p><p>We find that the northeastern margin of the larger inverted area generally has a thick-skinned style. Here, reverse reactivation of the rift-bounding master fault is coupled between the strata above and below the salt. Oppositely, the southwestern margin has a thin-skinned style. Here, buttressed hangingwall folds sit above reverse faults detaching into even thin evaporite sequences. The strike of this cover-fault trend mimics that of the underlying basement faults, although they dip in opposite directions. A triangle-zone model explains how sub-salt shortening (reactivation of major basement faults) can be balanced to the shortening observed in the sedimentary cover. As the current thickness of Permian salt increases and mobile-salt structures become predominant towards the south, the effects of basin inversion grow difficult to distinguish from those of halokinesis.</p><p>Interestingly, the shallow crests of inversion folds, especially along the southwestern margin, host groups of smaller normal faults. These formed to some degree during inversion, indicating that local extensional tectonism (crestal collapse) took place during the overall shortening. We conclude that the shallow parts of the folds experienced forced bending rather than buckling during folding.</p><p>A significant number of hydrocarbon reservoirs sit within basin-inversion structures. Potentially, this work can increase our understanding of deformation within these and similar structures.</p><p><em>Acknowledgements: We thank the Centre for Oil and Gas – DTU (DHRTC) for funding and supporting this project and for providing data. We also thank Schlumberger and Eliis for providing seismic-interpretation software.</em></p>

Quaternary evolution of the northern North Sea

2020 ◽  
Author(s):  
Christine Batchelor ◽  
Dag Ottesen ◽  
Benjamin Bellwald ◽  
Sverre Planke ◽  
Helge Løseth ◽  
...  
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
3D Seismic ◽  
Quaternary Sediments ◽  
The North ◽  
The North Sea ◽  
Data Coverage ◽  
Northern North Sea ◽  
2D And 3D ◽  
3D Seismic Data

<p>The North Sea has arguably the most extensive geophysical data coverage of any glacier-influenced sedimentary regime on Earth, enabling detailed investigation of the thick (up to 1 km) sequence of Quaternary sediments that is preserved within the North Sea Basin. At the start of the Quaternary, the bathymetry of the northern North Sea was dominated by a deep depression that provided accommodation for sediment input from the Norwegian mainland and the East Shetland Platform. Here we use an extensive database of 2D and 3D seismic data to investigate the geological development of the northern North Sea through the Quaternary.</p><p>Three main sedimentary processes were dominant within the northern North Sea during the early Quaternary: 1) the delivery and associated basinward transfer of glacier-derived sediments from an ice mass centred over mainland Norway; 2) the delivery of fluvio-deltaic sediments from the East Shetland Platform; and 3) contourite deposition and the reworking of sediments by contour currents. The infilling of the North Sea Basin during the early Quaternary increased the width and reduced the water depth of the continental shelf, facilitating the initiation of the Norwegian Channel Ice Stream.</p>

Extensive, Gas-charged Quaternary Sand Accumulations of the Northern North Sea and North Sea Fan

2020 ◽  
Author(s):  
Benjamin Bellwald ◽  
Sverre Planke ◽  
Sunil Vadakkepuliyambatta ◽  
Stefan Buenz ◽  
Christine Batchelor ◽  
...  
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Data Sets ◽  
3D Seismic ◽  
Fine Grained ◽  
The North ◽  
Northern North Sea ◽  
Well Data ◽  
Sea Fan ◽  
3D Seismic Data

<p>Sediments deposited by marine-based ice sheets are dominantly fine-grained glacial muds, which are commonly known for their sealing properties for migrating fluids. However, the Peon and Aviat hydrocarbon discoveries in the North Sea show that coarse-grained glacial sands can occur over large areas in formerly glaciated continental shelves. In this study, we use conventional and high-resolution 2D and 3D seismic data combined with well information to present new models for large-scale fluid accumulations within the shallow subsurface of the Norwegian Continental Shelf. The data include 48,000 km<sup>2</sup> of high-quality 3D seismic data and 150 km<sup>2</sup> of high-resolution P-Cable 3D seismic data, with a vertical resolution of 2 m and a horizontal resolution of 6 to 10 m in these data sets. We conducted horizon picking, gridding and attribute extractions as well as seismic geomorphological interpretation, and integrated the results obtained from the seismic interpretation with existing well data.</p><p>The thicknesses of the Quaternary deposits vary from hundreds of meters of subglacial till in the Northern North Sea to several kilometers of glacigenic sediments in the North Sea Fan. Gas-charged, sandy accumulations are characterized by phase-reserved reflections with anomalously high amplitudes in the seismic data as well as density and velocity decreases in the well data. Extensive (>10 km<sup>2</sup>) Quaternary sand accumulations within this package include (i) glacial sands in an ice-marginal outwash fan, sealed by stiff glacial tills deposited by repeated glaciations (the Peon discovery in the Northern North Sea), (ii) sandy channel-levee systems sealed by fine-grained mud within sequences of glacigenic debris flows, formed during shelf-edge glaciations, (iii) fine-grained glacimarine sands of contouritic origin sealed by gas hydrates, and (iv) remobilized oozes above large evacuation craters and sealed by megaslides and glacial muds. The development of the Fennoscandian Ice Sheet resulted in a rich variety of depositional environments with frequently changing types and patterns of glacial sedimentation. Extensive new 3D seismic data sets are crucial to correctly interpret glacial processes and to analyze the grain sizes of the related deposits. Furthermore, these data sets allow the identification of localized extensive fluid accumulations within the Quaternary succession and distinguish stratigraphic levels favorable for fluid accumulations from layers acting as fluid barriers.</p>

scholarly journals Delineation of shallow channel geometry and infill lithology using Spectral decomposition and seismic attributes: A case study from the North Sea Basin, Netherlands

2017 ◽  
Author(s):  
Kenneth Samuel Okiongbo ◽  
Righteous Ombu
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Spectral Decomposition ◽  
Negative Curvature ◽  
Seismic Facies ◽  
3D Seismic ◽  
Channel Geometry ◽  
The North ◽  
The North Sea ◽  
3D Seismic Data

Abstract. In the Southern North Sea, 3D seismic data had been widely acquired to explore for hydrocarbons, but interpretations of these datasets until now focus mainly on the deep exploration targets of the petroleum companies. Less attention is given to shallow sediments. But these sediments often contain channels that can serve as potential reservoir units. Thus the mapping and identification of these shallow channels and defining their infill lithology is important. In this study, seismic spectral decomposition technique has been used to delineate shallow thin channel geometry in a 3D seismic data acquired in the Dutch sector of the North Sea. The concurrent interpretation of curvature and coherence cubes with seismic facies analysis based on reflection terminations and geometry, amplitude and continuity enables the discrimination between shale versus sand filled channels. The results of the spectral decomposition show two distinct low sinuosity channel features in NNE–SSW direction but becomes diffuse towards the North. The strong negative curvature anomaly along the channels's axes observed in the most negative curvature attribute implies that the sediments within the channels have undergone more compaction. These strong negative curvature anomalies are interpreted to be due to differential compaction of shale filled channels.

Exploring mechanisms and rates of tunnel valley formation beneath deglaciating mid-latitude ice sheets using high-resolution 3D seismic data and numerical modelling

2021 ◽  
Author(s):  
James Kirkham ◽  
Kelly Hogan ◽  
Robert Larter ◽  
Ed Self ◽  
Ken Games ◽  
...  
Keyword(s):  
High Resolution ◽  
North Sea ◽  
Seismic Data ◽  
Ice Sheets ◽  
3D Seismic ◽  
Ice Dynamics ◽  
The North ◽  
The North Sea ◽  
State Water ◽  
3D Seismic Data

<p>The geological record of landforms produced beneath deglaciating ice sheets offers insights into otherwise inaccessible subglacial processes. Large subglacial channels formed by meltwater erosion of sediments (tunnel valleys) are widespread in formerly glaciated regions such as the North Sea. These features have the potential to inform basal melt rate parameterisations, realistic water routing and the interplay between basal hydrology and ice dynamics in numerical ice‑sheet models; however, the mechanisms and timescales over which tunnel valleys form remain poorly understood. Here, we present a series of modelling experiments, informed by geophysical observations from novel high-resolution 3D seismic data (6.25 m bin size, ~3.5 m vertical resolution), which test different hypotheses of tunnel valley formation and calculate the rates at which these features likely form beneath deglaciating ice sheets. Reconstructions of the former British-Irish and Fennoscandian ice sheets from a 3D thermomechanical ice‑sheet model (BRITICE CHRONO version 2) are used to calculate subglacial water routing and steady-state water discharges as these ice sheets retreated across the North Sea Basin during the last glaciation. Using these simulations, we calculate potential meltwater channel erosion rates and estimate how quickly tunnel  valleys are formed beneath deglaciating ice sheets in warmer than present-day climates. We find little evidence for widespread water ponding which may have led to channel formation through outburst floods. Instead, our results demonstrate that seasonal surface melt delivered to the bed could incise large channels of comparable dimensions to tunnel valleys over timescales of several hundred years as these ice sheets deglaciated.  </p>

Diapiric shale and coast-perpendicular, fault-related subbasins, south Texas Gulf Coast

2015 ◽  
Vol 3 (2) ◽  
pp. T43-T56 ◽  
Author(s):  
Osareni C. Ogiesoba ◽  
Rodolfo Hernandez
Keyword(s):  
Seismic Data ◽  
Gulf Coast ◽  
Structural Features ◽  
South Texas ◽  
3D Seismic ◽  
Texas Gulf Coast ◽  
Vertical Loading ◽  
The North ◽  
Visualization Tools ◽  
3D Seismic Data

Coast-perpendicular shale ridges are rare structural features worldwide, and their origin remains a subject of debate. We studied some coast-perpendicular shale ridges and faults within a minibasin located onshore in Refugio County in the Texas Gulf Coast. We used 3D seismic data, visualization tools, and seismic attributes to examine the geometry of coast-perpendicular diapiric structures associated subbasins (SBs) and faults, and coast-parallel listric faults. Our results indicated that the minibasin is subdivided into four SBs by five diapiric shale ridges that intrude through the fault heaves of down-to-the-basin (synthetic) and coast-perpendicular faults. Three of the SBs are oriented perpendicular to the coast, whereas the fourth has a curvilinear form trending northeast–southwest–southeast. Of the five diapiric shale ridges, three are coast-perpendicular. The other two are curvilinear to the coast. All five diapiric shale ridges are associated with coast-perpendicular faults that bound the flanks of the ridges. On the basis of our mapping results, we deduced that the origin of the coast-perpendicular faults in the study area are related to the coalescing of en echelon synthetic faults, as well as the coalition of synthetic and antithetic fault planes. We inferred that the origin of the shale diapirs is related to vertical loading and, possibly, local southwest–northeast lateral compression of interbedded, overpressured, shale-prone intervals. The coast-perpendicular faults within the Frio formed as a result of reactivation of the Eocene-Vicksburg coast-perpendicular faults. Synthetic faults dominate the pattern within the SB in the north where shale ridges are broad, whereas antithetic faults dominate the pattern in the south where shale ridges are narrow.

Assessing the feasibility of large-scale hydrogen storage in salt caverns on the UKCS using 3D seismic data

2021 ◽  
Author(s):  
Hector Barnett ◽  
Mark T. Ireland ◽  
Sanem Acikalin
Keyword(s):  
Risk Assessment ◽  
Hydrogen Storage ◽  
North Sea ◽  
Seismic Data ◽  
Large Scale ◽  
3D Seismic ◽  
Southern North Sea ◽  
The Uk ◽  
Salt Caverns ◽  
3D Seismic Data

<p>The energy industry in the UK faces a challenge to decarbonize to support reaching net zero CO2 emissions by 2050. In nearly all scenarios emission reductions are characterized not only by energy demand reductions, but also the decarbonization of electricity and heating. The use of hydrogen as a replacement for natural gas is one proposed solution, where renewable hydrogen is either blended into the gas grid or used directly. To ensure continuity of supply large scale hydrogen storage will be needed to meet this demand.</p><p>Hydrogen has been stored in small volumes (<25GWh) in salt caverns at various locations onshore in the United Kingdom since 1959. These caverns store hydrogen for industrial usage. In order to meet the demand for energy related hydrogen storage an increasing number of new and potentially larger storage options will be needed. Engineering of larger salt caverns for a hydrogen energy system will require thick salt formations which are optimally located with respect to both the hydrogen production facility and the end use. The Permian and Triassic salts deposits of both the Southern North Sea and the East Irish Sea offer vast areas for potential cavern development. Previous studies have described the landscape of underground gas storage onshore and offshore the UK, but to date there have been few detailed geophysical and geological studies on the hydrogen storage potential offshore.</p><p>The identification of suitable storage sites requires an understanding of the subsurface geology including potential structural discontinuities which could compromise the integrity of storage sites and be pathways for leakage. This analysis of hydrogen storage sites will utilise extensive existing modern 3D seismic data and well data taken from the Southern North Sea. We describe the geological setting of the Permo-triassic salt in the SNS in relation to the potential to develop salt cavern storage and develop play risk assessment maps. These risk assessment maps form part of a play fairway analysis workflow in order to identify the optimal storage sites for hydrogen on the UCKS.</p>

A Late Paleozoic sill complex and related paleo-topography in the eastern North Sea analyzed using 3D seismic data

2016 ◽  
Vol 674 ◽  
pp. 76-88 ◽  
Author(s):  
Ole Rønø Clausen ◽  
Katrine Juul Andresen ◽  
Jens Andreas Rasmussen
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Late Paleozoic ◽  
3D Seismic ◽  
3D Seismic Data
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