The Knarr Field: a new development at the northern edge of the North Sea

2017 ◽  
Vol 8 (1) ◽  
pp. 445-454 ◽  
Author(s):  
Silje S. Skarpeid ◽  
James M. Churchill ◽  
Jamie P. J. Hilton ◽  
Chris N. Izatt ◽  
Matthew T. Poole
Keyword(s):  
North Sea ◽  
Burial Depth ◽  
Reservoir Properties ◽  
Shallow Marine ◽  
The North ◽  
New Development ◽  
The North Sea ◽  
Northern Edge ◽  
Good For ◽  
Original Oil In Place

AbstractThe Knarr Field is located in the northern Norwegian North Sea, beyond the Brent Group delta fairway. Knarr was discovered in 2008 with the Jordbær well, additional resources were added to the field in 2011 with the successful Jordbær Vest well. The field extends over an area of approximately 20 km2. The original oil in place is estimated to be 26 MSm3 (163 MBBL). The reservoir is the Late Pliensbachian Cook Formation and its current burial depth is approximately −3700 m true vertical depth subsea (TVDSS). In Knarr, the Cook Formation is split into five sandstones that are separated by four shale intervals which can be correlated across the field. The three lower sands (Lower Cook) are interpreted to have been deposited in a tidally-dominated environment, while the upper two sandstones (Upper Cook) were deposited in a wave-dominated shallow-marine setting. The reservoir properties of the Cook Formation in the Knarr area are remarkably good for a reservoir at this depth, with porosities up to 28% and permeabilities in excess of 1 D. The good reservoir properties are the result of grain-coating chlorite, which has inhibited diagenetic quartz development. The field is developed with three oil producers and three water injectors produced via a floating production storage and offloading vessel (FPSO). First oil was achieved in March 2015.

Shallow marine Lower and Middle Miocene deposits at the southern margin of the North Sea Basin (northern Belgium): dinoflagellate cyst biostratigraphy and depositional history

2000 ◽  
Vol 137 (4) ◽  
pp. 381-394 ◽  
Author(s):  
S. LOUWYE ◽  
J. DE CONINCK ◽  
J. VERNIERS
Keyword(s):  
North Sea ◽  
Depositional Environment ◽  
Middle Miocene ◽  
Depositional History ◽  
Shallow Marine ◽  
Dinoflagellate Cyst ◽  
Southern North Sea ◽  
The North ◽  
Southern Margin ◽  
The North Sea

Detailed dinoflagellate cyst analysis of the Lower–Middle Miocene Berchem Formation at the southernmost margin of the North Sea Basin (northern Belgium) allowed a precise biostratigraphical positioning and a reconstruction of the depositional history. The two lower members of the formation (Edegem Sands and decalcified Kiel Sands) are biostratigraphically regarded as one unit since no significant break within the dinocyst assemblages is observed. The base of this late (or latest) Aquitanian–Burdigalian unit coincides with sequence boundary Aq3/Bur1 as defined by Hardenbol and others, in work published in 1998. A hiatus at the Lower–Middle Miocene transition separates the upper member (the Antwerpen Sands) from the underlying member. The greater part of the Antwerpen Sands were deposited in a Langhian (latest Burdigalian?)–middle Serravallian interval. The base of this unit coincides with sequence boundary Bur5/Lan1. Biostratigraphical correlation points to a diachronous post-depositional decalcification within the formation since parts of the decalcified Kiel Sands can be correlated with parts of the calcareous fossil-bearing section, up to now interpreted as Antwerpen Sands. The dinoflagellate cyst assemblages are dominated by species with a inner neritic preference, although higher numbers of oceanic taxa in the upper part of the formation indicate incursions of oceanic watermasses into the confined depositional environment of the southern North Sea Basin.

scholarly journals Geophysical imaging of porosity variations in the Danish North Sea chalk

2008 ◽  
Vol 15 ◽  
pp. 17-20 ◽  
Author(s):  
Tanni Abramovitz
Keyword(s):  
North Sea ◽  
Seismic Reflection ◽  
Seismic Inversion ◽  
Rock Properties ◽  
Well Log ◽  
Reservoir Properties ◽  
Seismic Reflection Data ◽  
Log Data ◽  
The North ◽  
The North Sea

More than 80% of the present-day oil and gas production in the Danish part of the North Sea is extracted from fields with chalk reservoirs of late Cretaceous (Maastrichtian) and early Paleocene (Danian) ages (Fig. 1). Seismic reflection and in- version data play a fundamental role in mapping and characterisation of intra-chalk structures and reservoir properties of the Chalk Group in the North Sea. The aim of seismic inversion is to transform seismic reflection data into quantitative rock properties such as acoustic impedance (AI) that provides information on reservoir properties enabling identification of porosity anomalies that may constitute potential reservoir compartments. Petrophysical analyses of well log data have shown a relationship between AI and porosity. Hence, AI variations can be transformed into porosity variations and used to support detailed interpretations of porous chalk units of possible reservoir quality. This paper presents an example of how the chalk team at the Geological Survey of Denmark and Greenland (GEUS) integrates geological, geophysical and petrophysical information, such as core data, well log data, seismic 3-D reflection and AI data, when assessing the hydrocarbon prospectivity of chalk fields.

scholarly journals The Size Of Mature Plaice, Turbot, And Brill, On Different Fishing Grounds

1896 ◽  
Vol 4 (2) ◽  
pp. 97-107 ◽  
Author(s):  
J. T. Cunningham
Keyword(s):  
North Sea ◽  
Careful Examination ◽  
Mature Specimen ◽  
The North ◽  
Large Size ◽  
Actual Fact ◽  
The North Sea ◽  
Good For

In the previous number of the Journal, I described my reasons for doubting whether the conclusions drawn by Mr. Holt, concerning the size at which plaice become mature, would hold good for the whole of the North Sea; and also whether the evidence he relied upon, in distinguishing mature and immature plaice, was sufficient. I stated that, as an actual fact, one sample of mature plaice, which were much below the limits of size determined by Mr. Holt, had come into my hands. I suggested, as a probability, that the presence of dead degenerating eggs in the tissue of the ovary was a proof that the fish had spawned, was a spent, and therefore a mature specimen. My words were: “It cannot be asserted as a certainty that these granular masses never occur in an immature ovary; to settle the doubt it will be necessary to make a careful examination of plaice in November and December, when all fish which are about to spawn will have a large amount of yolk in the eggs, and all fish in which the eggs are transparent and yolkless must be immature.” It was already known that these degenerating eggs do occur in spent ovaries, from which the ripe eggs have recently been discharged, and which bear evidence of the fact in their somewhat large size, flaccid and collapsed condition, and usually in the presence of a few detached ripe eggs in their interior.

The Maria Field, Block 16/29a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 875-885 ◽  
Author(s):  
I. N. Stephens ◽  
S. Small ◽  
P. H. Wood
Keyword(s):  
North Sea ◽  
Upper Jurassic ◽  
Reservoir Properties ◽  
The North ◽  
Recoverable Reserves ◽  
Fault Block ◽  
Production Wells ◽  
The North Sea ◽  
The Uk ◽  
Clay Formation

AbstractThe Maria oilfield is located on a fault-bounded terrace in Block 16/29a of the UK sector of the North Sea, at the intersection of the South Viking Graben and the eastern Witch Ground Graben. The field was discovered in December 1993 by the 16/29a-11Y well and was confirmed by two further appraisal wells. The reservoir consists of shoreface sandstones of the Jurassic Fulmar Formation. The Jurassic sandstones, ranging from 100 to 180 ft in thickness, have variable reservoir properties, with porosities ranging from 10 to 18% and permeabilities from 1 to 300 mD. Hydrocarbons are trapped in a truncated rotated fault block, striking NW–SE. The reservoir sequence is sealed by Kimmeridge Clay Formation and Heather Formation claystones. Geochemical analysis suggests that Middle Jurassic Pentland Formation and Upper Jurassic Kimmeridge Clay Formation mudstones have been the source of the Maria hydrocarbons. Estimated recoverable reserves are 10.6 MMbbl and 67 bcf (21.8 MMboe). Two further production wells were drilled in 2018 to access unexploited areas.

Field emission scanning electron microscopy — a high-resolution technique for the study of clay minerals in sediments

Clay Minerals ◽  
1997 ◽  
Vol 32 (2) ◽  
pp. 197-203 ◽  
Author(s):  
J. M. Huggett ◽  
H. F. Shaw
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
North Sea ◽  
Burial Depth ◽  
The North ◽  
The North Sea ◽  
High Resolution Technique ◽  
Field Emission Electron Microscopy ◽  
Drilling Muds ◽  
Scanning Electron

AbstractThe use of field emission electron microscopy for the study of clay mineral petrography in mudrocks and sandstones is discussed. The methodology including sample preparation is outlined and three examples of the application of the technique are described: the formation of authigenic illite in mudrocks, the multiple generation of authigenic illites in sandstones and the effects of KCl drilling muds on shale fabrics. In the study of authigenic illite formation in Palaeocene mudrocks from the North Sea, the FESEM analyses have demonstrated the formation of illites with increasing burial depth that conventional SEM and XRD analyses had failed to show. The FESEM analyses of the authigenic illites in Carboniferous sandstones from the southern North Sea revealed at least three different habits representing different generation episodes rather than one illite formation event.This has important repercussions with regard to the interpretation of stable isotope and dating data for the illites. Significant petrographic changes in shales after treatment with KCl drilling muds have been observed from FESEM analyses, suggesting reactivity between the shales and the KCl muds.

scholarly journals Diagenesis influencing the porosity of Upper Jurassic reservoir sandstones, Danish North Sea

2008 ◽  
Vol 15 ◽  
pp. 9-12 ◽  
Author(s):  
Rikke Weibel ◽  
Nynke Keulen
Keyword(s):  
North Sea ◽  
Source Area ◽  
Upper Jurassic ◽  
Burial History ◽  
Reservoir Properties ◽  
Thin Sections ◽  
The North ◽  
Diagenetic Alteration ◽  
The North Sea ◽  
Reservoir Sandstones

Upper Jurassic quartz-rich sandstones in the North Sea Basin are important reservoir rocks for oil and gas, and one of the latest discoveries of oil in the Danish sector was made in the area of the Hejre wells that penetrated such sediments (Fig. 1). The reservoir properties of sandstones are strongly influenced by diagenetic alteration, i.e. the mineralogical changes that take place during burial of the sediments. The diagenetic features depend on the source area, depositional setting, facies architecture and burial history of the sediment. The major diagenetic features influencing porosity in Upper Jurassic reservoir sandstones are feldspar dissolution and precipitation, preci-pitation of illite, calcite and quartz, and quartz stylolite formation. With regard to the Upper Jurassic sandstones in the Danish sector of the North Sea, the important question is: how can porosity be preserved in sediments buried at depths of more than 5 km? The Hejre-2 well penetrated the Upper Jurassic sediments (Fig. 2) before reaching pre-Upper Jurassic volcaniclastic conglomerates. The diagenetic features were studied in thin sections of core samples with traditional petrographic techniques using transmitted light microscopy supplemented by scanning electron microscopy (SEM) of rock chips and thin sections.

The Clyde Field, Block 30/17b, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 279-285
Author(s):  
D. A. Stevens ◽  
R. J. Wallis
Keyword(s):  
Production Rate ◽  
North Sea ◽  
Late Jurassic ◽  
Water Injection ◽  
Reservoir Quality ◽  
Reservoir Pressure ◽  
Shallow Marine ◽  
The North ◽  
Fault Block ◽  
The North Sea

AbstractThe Clyde Field, which was discovered in 1978, is located on the SW edge of the North Sea Central Graben. The reservoir is developed with Late Jurassic shallow marine sands of the Fulmar Sand Formation. An estimated 408 MMBBL of oil is present (Annex B), of which 154 MMBBL is considered recoverable.The structure of the Clyde Field takes the form of a rotated Jurassic fault block, truncated at its crest by a major unconformity. Oil is retained within a combination trap, sourced from Late Jurassic Kimmeridge Clay thermally matured in the highly productive basinal lows, adjacent to the field.Reservoir sand quality is highly variable, ranging from excellent with permeabilities in excess of Id, to poor with permeabilities of less than 1 md. The principal control on reservoir quality appears to be original depositional texture, although strong diagenetic effects are also present.Production is from a single, centrally located, platform provided with thirty slots. Aquifer support is insufficient to maintain reservoir pressure at the current plateau production rate of 50 000 BOPD and so a programme of water injection has been implemented.

scholarly journals Lithostratigraphy of the Upper Oligocene – Miocene succession of Denmark

2010 ◽  
Vol 22 ◽  
pp. 1-92 ◽  
Author(s):  
Erik Skovbjerg Rasmussen ◽  
Karen Dybkjær ◽  
Stefan Piasecki
Keyword(s):  
North Sea ◽  
Middle Miocene ◽  
Three Dimensions ◽  
Marine Clay ◽  
Shallow Marine ◽  
North East ◽  
The North ◽  
Upper Oligocene ◽  
The North Sea ◽  
Delta Progradation

This paper presents a revised lithostratigraphic scheme for the uppermost Upper Oligocene – Miocene succession of Denmark. The marine Oligocene Brejning Clay Member is upgraded to formation status and includes the Sydklint Member and the Øksenrade Member (new). The shallow marine and deltaic deposits of mainly Early Miocene age are included in the Ribe Group (new) while the fully marine Middle and Upper Miocene clay-rich deposits are referred to the Måde Group (new). The Ribe Group is subdivided into 6 formations: the Vejle Fjord Formation is revised and includes the Skansebakke Member, the Billund Formation (new) includes the Addit and Hvidbjerg Members (new), the Klintinghoved Formation is redefined formally and includes the Koldingfjord Member (new), the Bastrup Formation (new) includes the Resen Member (new), the Vandel Member is a new member in the Arnum Formation (revised), the Odderup Formation is redefined and includes the Stauning Member (new) and the coalbearing Fasterholt Member. The Måde Group is subdivided into the Hodde, Ørnhøj (new), Gram and Marbæk (new) Formations. Subdivision of the Upper Oligocene – Miocene succession into two groups, the Ribe and Måde Groups, is compatible with the North Sea lithostratigraphic framework where they correlate with the upper part of the Hordaland Group and the Nordland Group, respectively. The revised lithostratigraphic framework correlated in three dimensions provides rigorous constraints on the palaeogeographic interpretation of the Late Oligocene – Miocene period. Three major deltaic units (Billund, Bastrup and Odderup Formations) prograded from the north and north-east into the North Sea Basin during the Early – early Middle Miocene. Delta progradation was punctuated by deposition of marine clay and silt associated with minor transgressive events (Vejle Fjord, Klintinghoved and Arnum Formations). During the Middle–Late Miocene, marine depositional conditions dominated (Hodde, Ørnhøj and Gram Formations). A fourth and final progadational event (Marbæk Formation) commenced in the latest Tortonian heralding the emergence of present-day Denmark (including the North Sea sector).

scholarly journals Variations in mineralization potential for CO2 related to sedimentary facies and burial depth – a comparative study from the North Sea

2014 ◽  
Vol 63 ◽  
pp. 5063-5070 ◽  
Author(s):  
Anja Sundal ◽  
Helge Hellevang ◽  
Rohaldin Miri ◽  
Henning Dypvik ◽  
Johan Petter Nystuen ◽  
...  
Keyword(s):  
Comparative Study ◽  
North Sea ◽  
Sedimentary Facies ◽  
Burial Depth ◽  
The North ◽  
Mineralization Potential ◽  
The North Sea

The Schooner Field, Blocks 44/26a, 43/30a, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 811-824 ◽  
Author(s):  
A. Moscariello
Keyword(s):  
North Sea ◽  
Gas Production ◽  
Production Data ◽  
Reservoir Properties ◽  
Upper Carboniferous ◽  
The North ◽  
The North Sea ◽  
Net To Gross ◽  
Reservoir Connectivity ◽  
Coal Measures

AbstractThe Schooner Field is Shell U.K.'s first Carboniferous gas development in the North Sea. The field was discovered in 1987 by well 44/26-2 and gas production began in October 1996 from four wells. In contrast to the majority of the fields in the Southern North Sea producing from the aeolian Leman Sandstones Formation (Rotliegend), Schooner targets the low net-to-gross, fluvial Upper Carboniferous Barren Red Measures and Coal Measures formations. The reservoir consists of discrete, low sinuosity fluvio-deltaic channels draining a swampy coastal floodplain evolving upwards into a highly aggrading, low gradient, distal fluvial fan, dominated by braided and anastomosing channels. In Schooner, like other Carboniferous fields, reservoir connectivity is one of the key subsurface uncertainties due both to channel lateral discontinuity and fault compartmentalization. Production data and reservoir properties distribution, together with a new stratigraphical subdivision driven mostly by chemostratigraphic techniques, have been used to reassess the volume of gas-in-place which currently is estimated at 29.98 Gm3 (1059 BCF)

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