scholarly journals Numerical forward modelling of the overpressure build-up in the Cenozoic section of the Central Graben in the North Sea

2021 ◽  
Vol 11 (4) ◽  
pp. 1621-1642
Author(s):  
Ivanka Orozova-Bekkevold ◽  
Thomas Guldborg Petersen
Keyword(s):  
Pressure Gradient ◽  
North Sea ◽  
Sedimentary Basins ◽  
Maximum Magnitude ◽  
Horizontal Pressure Gradient ◽  
The North ◽  
The North Sea ◽  
Horizontal Pressure ◽  
Model Set ◽  
Set Up

AbstractOne of the most widespread hypotheses for the origin of the present-day overpressure in the shale Post-Chalk section in the North Sea is the very rapid sedimentation from Neogene to present day. We tested this hypothesis by the means of numerical forward finite elements modelling and successfully simulated the overpressure build-up during the Cenozoic filling of the North Sea with relatively simple model set-up. Our model shows that overpressure of approximately 28% above hydrostatic developed in the Neogene, while during the Quaternary, it reached up to 36% above hydrostatic. At present day, the predicted onset of overpressure starts at about 800–1000 m below seafloor, while the maximum (magnitude about 1.36 sg, i.e. 36% above the normal hydrostatic pressure) is at approximately 2100 m. This overpressure profile fits reasonably well with data from wells drilled in the Central Graben. The exact magnitude of the overpressure depends on the used assumptions, the model set-up and the values of the input parameters. Especially the dynamic interaction between high sedimentation rates, clay permeability and low horizontal pressure gradient seems to be a key factor in the efficiency of dewatering of saturated clays during burial. The results indicate that, the assumption of horizontal stress isotropy results in nearly no horizontal fluid flow, despite the same magnitude for the vertical and the horizontal permeability. In these conditions, the vertical permeability plays much bigger role than the horizontal one in the effective de-watering of the sediments during burial. Further investigation is needed to explore the role of horizontal pressure gradient in fluid migration in passive sedimentary basins.

scholarly journals The Size of Diatoms II. Further Observations on Rhizosolenia styliformis (Brightwell)

1946 ◽  
Vol 26 (3) ◽  
pp. 271-284 ◽  
Author(s):  
R. S. Wimpenny
Keyword(s):  
North Sea ◽  
Indicator Species ◽  
Separate Species ◽  
Southern North Sea ◽  
Auxospore Formation ◽  
The North ◽  
The North Sea ◽  
Set Up ◽  
The Antarctic

1. Diameter measurements of Rhizosolenia styliformis from the Antarctic, the subtropical Atlantic and Pacific Oceans and from the North Sea and neighbouring waters have made it appear necessary to set up two varieties, oceanica and semispina, in addition to the type of the species R. styliformis. The type as I describe it has been called var. longispina by Hustedt, but elsewhere it has often been figured as the var. oceanica of this paper. Var. semispina is synonymous with the form represented by Karsten as R. semispina Hensen. It differs from R. semispina as drawn by Hensen and its synonym R. hebetata forma semispina Gran, but is thought likely to be linked by intermediates. If this is so R. hebetata may have to be extended to include and suppress R. styliformis, as var. semispina is linked to the type by intermediates. Var. oceanica has no intermediate forms and, if R. hebetata is to be extended, this variety should be established as a separate species.2. Var. oceanica is absent from the southern North Sea and appears to be an indicator species related to oceanic inflow.3. Auxospore formation was observed for the type in the southern North Sea in 1935 and biometric observations suggest that a period of 3-4 years elapsed between the production of auxospore generations in that area. Outside the southern North Sea for the type, measurements give no indication of auxospore generations occurring at intervals exceeding a year. While auxospore formation has been seen in var. oceanica from the Shetlands area samples of June 1935 and July 1938, this phenomenon has not been observed for var. semispina.

scholarly journals 7th Cambridge Diagenesis Conference 2011: an introduction

Clay Minerals ◽  
2014 ◽  
Vol 49 (2) ◽  
pp. 125-126
Author(s):  
C. V. Jeans ◽  
N. J. Tosca
Keyword(s):  
Clay Minerals ◽  
North Sea ◽  
Special Issue ◽  
Fundamental Study ◽  
Oil Companies ◽  
The North ◽  
Research Institutes ◽  
The North Sea ◽  
Set Up ◽  
Natural Laboratory

The Cambridge Diagenesis Conferences (1981–1998) were set up to act as a conduit for the interchange of clay mineral expertise between universities and research institutes on one hand, and the hydrocarbon industry on the other. At the time, oil companies were dealing with the development of the North Sea Oil Province which was turning out to be a natural laboratory for the fundamental study of authigenic clay minerals and their relationship to lithofacies, burial, overpressure, reservoir quality and hydrocarbon emplacement. This symbiosis between industry and academia flourished for nearly two decades. Each conference was followed by a special issue of Clay Minerals dealing with topics relevant to, or discussed at the particular meeting. By the late 1990s the North Sea had become a mature province and the major oil companies were looking to other parts of the world to replenish their reserves.

Velocity and interface depth determination by tomography of depth migrated gathers

Geophysics ◽  
1996 ◽  
Vol 61 (5) ◽  
pp. 1511-1523 ◽  
Author(s):  
Dan Kosloff ◽  
John Sherwood ◽  
Zvi Koren ◽  
Elana Machet ◽  
Yael Falkovitz
Keyword(s):  
North Sea ◽  
Determination Method ◽  
Prestack Migration ◽  
Traveltime Tomography ◽  
The North ◽  
Depth Determination ◽  
The North Sea ◽  
Set Up

A method for velocity and interface depth determination based on tomography of migrated common reflecting point (CRP) gathers is presented. The method is derived from the tomographic principle that relates traveltime change along a given ray to perturbations in slowness and layer depths. The tomographic principle is used to convert depth errors in migrated CRP gathers to time errors along a CRP ray pair and thus enable use of conventional traveltime tomography. It is also used to affect a very fast prestack migration and set up the tomography matrix. The velocity‐depth determination method uses the available offsets of all CRPs and inverts for the parameters of all layers simultaneously. Hand picking of depth errors on CRP gathers is avoided by a method where the tomography matrix operates directly on the migrated gathers. The velocity‐depth determination method is demonstrated on a synthetic example and on a field example from the North Sea.

Pre-Permian sedimentary basins in the North Sea: images from reprocessed and pre-stack depth migrated MONA LISA data

2002 ◽  
Vol 19 (5) ◽  
pp. 519-526 ◽  
Author(s):  
Gabriela Fernández Viejo ◽  
Mireille Laigle ◽  
César R Ranero
Keyword(s):  
North Sea ◽  
Sedimentary Basins ◽  
The North ◽  
The North Sea ◽  
Mona Lisa

Stratigraphy of the oil and gas reservoirs: UK Continental Shelf

1991 ◽  
Vol 14 (1) ◽  
pp. 9-18 ◽  
Author(s):  
Stewart Brown
Keyword(s):  
Continental Shelf ◽  
North Sea ◽  
Oil And Gas ◽  
Sedimentary Basins ◽  
Public Domain ◽  
The Public ◽  
The North ◽  
Marine Gravity ◽  
The North Sea ◽  
The Uk

The petroliferous sedimentary basins of the UK Continental Shelf are remarkable for the diversity of their reservoir strata. Reservoir rocks in fields currently in production range in age from Devonian to earliest Eocene, but significant hydrocarbon discoveries have also been made in rocks as as young as the mid-Eocene. The reservoirs are predominantly siliciclastic rocks, with facies ranging from continental fluvial and aeolian, to marine gravity flow deposits from sub-wave base environments.In this paper stratigraphic context of the producing horizons in the UK Continental Shelf (UKCS), principally the North Sea, is reviewed, and the sedimentation of the reservoir strata placed in an outline geological history. The main producing horizons are described in summary. Matters of stratigraphic terminology and correlation both between fields and between basins are discussed.A lithostratigraphy for the UK southern North Sea was established by Rhys (1974), and for the central and northern North Sea by Deegan & Scull (1977). Although these schemes have proved to be fairly robust, in the last 13 years the acquisition of new data plus a proliferation of new terms not fully documented in the public domain, argue strongly for a comprehensive revision and rationalization which is beyond the scope of this paper. Attempts in the public domain to standardize nomenclature across international boundaries in the North Sea, pursued by Deegan & Scull (1977) for the UK and Norwegian sectors, have lapsed for the most part in subsequent years.Economic basement in the UK North Sea can be regarded at present

scholarly journals A Healthy Metaphor? The North Sea Consultation and the Power of Words

2021 ◽  
Vol 13 (22) ◽  
pp. 12905
Author(s):  
Haye Geukes ◽  
Udo Pesch ◽  
Aad Correljé ◽  
Behnam Taebi
Keyword(s):  
North Sea ◽  
Reflective Equilibrium ◽  
Decisive Role ◽  
Conservation Areas ◽  
Consultation Process ◽  
The North ◽  
Fishing Sector ◽  
The North Sea ◽  
Set Up ◽  
Power Of Words

The North Sea Consultation was set up to resolve conflicting claims for space in the North Sea. In 2020, this consultation process resulted in the North Sea Agreement, which was supported by the Dutch Parliament and cabinet as a long-term policy; however, the fishing sector felt excluded, left the consultation process, and does not support the agreement. Using semi-constructed interviews and the method of wide reflective equilibrium, this research found that in this conflict the metaphor of ‘health’ has played a decisive role. While all stakeholders want to keep the sea ‘healthy’, they disagree on what a healthy sea actually means, leading to contrastive positions on the desirability of trawler fishing, wind parks, and conservation areas—the North Sea Agreement’s main foci of interest. To prevent the unproductive escalation of such a conflict, it is inevitable to acknowledge the moral connotations of such metaphors, as this allows a decision-making process that can be considered more just.

I: The English Flood of 1953

1957 ◽  
Vol 16 (2) ◽  
pp. 3-5 ◽  
Author(s):  
John Spiegel
Keyword(s):  
Comparative Study ◽  
North Sea ◽  
The North ◽  
Disaster Studies ◽  
The North Sea ◽  
Set Up

The National Research Council's Committee on Disaster Studies sent us to England about two weeks after the North Sea flood of February 1, 1953, to set up a rather extensive comparative study of the flood's effects in several communities. Unfortunately, the larger study did not materialize and we were compelled to learn what we could by ourselves in about two weeks. The following report, therefore, must be regarded as very tentative. It deals with Kimbark1, one of the two flooded communities we were able to study.

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