The Moira Field, Block 16/29a, UK Central North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 603-609
Author(s):  
Peter M. Chandler ◽  
Barbara Dickinson
Keyword(s):  
North Sea ◽  
Middle Jurassic ◽  
Submarine Fan ◽  
Fault Block ◽  
Reservoir Porosity ◽  
Central North Sea

AbstractThe Moira Field, discovered in 1988, lies on the Maureen Shelf, 10 km SSW of the Maureen Field. The reservoir comprises submarine fan sandstones in a four-way dip closure, draped over a Middle Jurassic fault block. The good quality reservoir (porosity 17-25%, permeability 80-400mD) flowed 5100 BOPD of 42° API oil in the discovery well. STOIIP was initially calculated as 20 MMBBL, but seismic pick and depth conversion uncertainites were revealed by later drilling. The most recent (1998) calculation yielded STOIIP of 12.4 MMBBL. Reserves of 4.2 MMBBL (34%), have been produced through a single deviated well tied-back to the Maureen platform. The field was shut-in in 1999.

The Dunlin Field, Blocks 211/23a and 211/24a, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 95-102 ◽  
Author(s):  
A. Baumann ◽  
B. O'Cathain
Keyword(s):  
North Sea ◽  
Middle Jurassic ◽  
Upper Jurassic ◽  
Reservoir Properties ◽  
Oil Accumulation ◽  
Western Margin ◽  
Shetland Islands ◽  
Fault Block ◽  
Delta System ◽  
Cumulative Production

AbstractThe Dunlin Oilfield is located in the East Shetland Basin, 160 km northeast of the Shetland Islands. It lies in UK Blocks 211/23a and 211/24a in about 500 ft of water. The field was discovered in June 1973 by well 211/23-1. The oil accumulation is trapped, in a north-south oriented, tilted fault block at the western margin of the Viking Graben, at a depth of about 8500 ft TVSS. The reservoir is contained in the formations of the Middle Jurassic Brent Group. In the Dunlin area they form a 450 ft thick sequence of sands and intercalated minor shales, which has been deposited by a shore face and delta system prograding northwards across the Viking Graben. The seal is formed by the shales of the Middle/Upper Jurassic Heather Formation. Reservoir properties of the Brent sands are fair to good with porosities of up to 30% and average permeabilities in the range from 10 to 4000 md. Development of the field is carried out from a single platform, from which production started in 1978. To date 40 development wells have been drilled and the total cumulative production amounts to 282 MMBBL of an ultimate recovery of 363 MMBBL.

The Ninian Field, Blocks 3/3 & 3/8, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 175-182 ◽  
Author(s):  
E. J. Van Vessem ◽  
T. L. Gan
Keyword(s):  
North Sea ◽  
Middle Jurassic ◽  
Water Flooding ◽  
The West ◽  
West Side ◽  
Field Development ◽  
Fault Block ◽  
Northern North Sea ◽  
Original Oil In Place

AbstractThe Ninian Field, located in the northern North Sea, lies in the East Shetland Basin on the west side of the Viking Graben. The field straddles Blocks 3/3 and 3/8 and is developed under a unitization agreement with Chevron UK Limited as operator. The structure is a westward tilted fault block. The estimated original oil-in-place contained in the marine-deltaic sandstones of the Middle Jurassic Brent Group, is 2920 MMBBL, of which an estimated 35 to 40% is recoverable. The oil is a paraffinic-naphthenic type with an API gravity of 36°. The field development consists of three fixed platforms with a total of 109 drilling slots. The natural drive in the field is negligible so that water flooding is required. The production of the Ninian Field started in December 1978 and reached a peak of 315 000 BOPD in the summer of 1982. At the end of 1988 over 811 MMBBL had been produced.

The Magnus Field, Block 211/7a, 12a, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 153-157 ◽  
Author(s):  
M. Shepherd
Keyword(s):  
North Sea ◽  
Upper Jurassic ◽  
Hydrocarbon Source Rock ◽  
Submarine Fan ◽  
Oil Accumulation ◽  
The North ◽  
Fault Block ◽  
The North Sea ◽  
The Uk ◽  
Clay Formation

abstractMagnus is the most northerly producing field in the UK sector of the North Sea. The oil accumulation occurs within sandstones of an Upper Jurassic submarine fan sequence. The combination trap style consists of reservoir truncation by unconformity at the crest of the easterly dipping fault block structure and a stratigraphic pinchout element at the northern and southern limits of the sand rich fan. The reservoir is enveloped by the likely hydrocarbon source rock, the organic rich mudstones of the Kimmeridge Clay Formation.

The Auk Field, Block 30/16, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 227-236 ◽  
Author(s):  
Nigel H. Trewin ◽  
Mark G. Bramwell
Keyword(s):  
North Sea ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
The South ◽  
Well Control ◽  
Western Margin ◽  
The North ◽  
Fault Block ◽  
Definition Of ◽  
Central North Sea

AbstractThe Auk field is located in Block 30/16 at the western margin of the Central Graben. Oil is contained in a combination stratigraphic and structural trap which is sealed by Cretaceous chalk and Tertiary claystones. An oil column of up to 400 ft is contained within Rotliegend sandstones, Zechstein dolomites, Lower Cretaceous breccia and Upper Cretaceous chalk. Production has taken place since 1975 with 80% coming from the Zechstein, in which the best reservoir lithology is a vuggy fractured dolomite where porosity is entirely secondary due to the dolomitization process and leaching of evaporites. Both Rotliegend dune slipface sandstones, and the Lower Cretaceous breccia comprising porous Zechstein clasts in a sandy matrix, also contribute to production. Poor seismic definition of the reservoir results in reliance on well control for detailed reservoir definition. The field has an estimated ultimate recovery of 93 MMBBL with 13 MMBBL remaining at the end of 1988.The Auk field is situated in Block 30/16 of the Central North Sea about 270 km ESE from Aberdeen in 240-270 ft of water (Fig. 1). The field covers an area of about 65 km2 and is a combination of tilted horst blocks and stratigraphic traps, located at the western margin of the South West Central Graben. The Auk horst is about 20 km long and 6-8 km wide, with a NNW-SSE trend. It is bounded on the west by a series of faults with throws of up to 1000 ft, and the eastern boundary fault has a throw of 5000 ft in the north reducing to zero in the south (Fig. 2). The horst is a westward tilted fault block in the north which grades into a faulted anticline in the south. The Auk accumulation is largely contained within Zechstein dolomites and is ultimately sealed by Cretaceous chalk which overlies the base Cretaceous erosion surface. An E-W cross-section of the field is illustrated by Fig. 3. Auk was the first of the alphabetical sequence of North Sea sea-bird names used for Shell/ Esso fields.

The Staffa Field, Block 3/8b, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 327-333 ◽  
Author(s):  
J. G. Gluyas ◽  
J. R. Underhill
Keyword(s):  
North Sea ◽  
Middle Jurassic ◽  
Recovery Factor ◽  
Small Field ◽  
Solvent Treatment ◽  
Fault Block ◽  
Northern North Sea

AbstractThe Staffa Field occurs at the crest of an intermediate tilted fault block that is located between the Ninian and Alwyn fields in the northern North Sea. The partnership BP, Lasmo and Ranger discovered the field with well 3/8b-10 in 1985. By 1990, BP had left the partnership while Lasmo and Ranger had received Annex B approval for development. First production from this small field reservoired in sandstones belonging to the Middle Jurassic, Brent Group was obtained in 1992. At sanction, reserves were estimated to be about 5.5 MMBBL together with 26.8 BCF corresponding to a recovery factor of 18%. Field life was expected to be about 7.5 years (to 2000) and the plateau length six months. Although initial production exceeded the planned plateau rate of 8000 BOPD, production ceased in June 1993 when the pipeline to Ninian became blocked with wax or wax hydrates. Remedial solvent treatment failed to remove the blockage and replacement of the blocked section was undertaken. This too became blocked soon after resumption of production and the field was shut-in in November 1994. It was then abandoned, since further replacement of the line was not justified economically. At abandonment the field had produced 3.9 MMBBL of oil, 0.296 MMBBL of NGL and 6.457 BCF of gas Gust 13% of its original STOIIP).

The Murchison Field, Block 211/19a, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 165-173
Author(s):  
John Warrender
Keyword(s):  
North Sea ◽  
Middle Jurassic ◽  
Upper Jurassic ◽  
Lower Jurassic ◽  
Oil Field ◽  
Medium Size ◽  
Fault Block ◽  
International Boundary ◽  
Northern North Sea ◽  
The Uk

AbstractThe Murchison oil field forms part of the Brent oil province in the East Shetland Basin, northern North Sea. The field, which straddles the UK-Norway international boundary, was discovered in 1975 and began production with Conoco (UK) Ltd as Operator, in 1980. Like many oil accumulations in the East Shetland Basin the trap consists of a northwesterly dipping rotated fault block of Jurassic-Triassic age sourced and sealed by unconformable Upper Jurassic shales. The productive reservoir consists of Middle Jurassic Brent Group sandstones which represent the south to north progradation of a wave/tide influenced delta system. The Brent Group on Murchison has an average thickness of 425 ft with average porosities of 22% and permeabilities in the 500-1000 md range in producing zones. The maximum hydrocarbon column thickness is approximately 600 ft. The oil is undersaturated and no gas cap is present. Recoverable reserves are 340 MMBBL from a total oil in place figure of 790 MMBBL. Oil production which is via a single steel jacket platform peaked at 127 000 BOPD in 1983 and currently averages 45 000 BOPD. Economic field life is expected to be at least 20 years.The Murchison Field is located in the East Shetland Basin, northern North Sea at approximate latitude 61° 23' N, longitude 1° 43.5' E, 120 miles northeast of the Shetland Islands (Fig. 1). The field straddles the UK-Norway international boundary with the greater portion in the UK Block 21 l/19a and the lesser portion in Norway Block 33/9. Water depth is -512 ft BMSL. In the context of the North Sea the field is of medium size with an areal closure of approximately 7 square miles and contains 790 million barrels of oil in place. The productive reservoir consists of coastal deltaic sandstones of the Middle Jurassic Brent Group which lie between the marine shales of the Lower Jurassic Dunlin Group and the marine, organic-rich shales of the Upper Jurassic Humber Group. The trap is structural comprising a single, northwesterly dipping rotated fault block which has been sourced and sealed by the overlying Upper Jurassic shales. The field is named after the Scottish geologist Sir Roderick Impey Murchison (1792-1871), who is best known for his contribution to Palaeozoic stratigraphy.

scholarly journals Jurassic lithostratigraphy and stratigraphic development onshore and offshore Denmark

2003 ◽  
Vol 1 ◽  
pp. 145-216 ◽  
Author(s):  
Olaf Michelsen ◽  
Lars H. Nielsen ◽  
Peter N. Johannessen ◽  
Jan Andsbjerg ◽  
Finn Surlyk
Keyword(s):  
North Sea ◽  
Middle Jurassic ◽  
Upper Jurassic ◽  
Lower Jurassic ◽  
Coarse Grained ◽  
Late Triassic ◽  
New Members ◽  
Shallow Marine ◽  
Central North Sea ◽  
Sea Area

A complete updated and revised lithostratigraphic scheme for the Jurassic succession of the onshore and offshore Danish areas is presented together with an overview of the geological evolution. The lithostratigraphies of Bornholm, the Danish Basin and the Danish Central Graben are described in ascending order, and a number of new units are defined. On Bornholm, the Lower–Middle Jurassic coal-bearing clays and sands that overlie the Lower Pliensbachian Hasle Formation are referred to the new Sorthat Formation (Lower Jurassic) and the revised Bagå Formation (Middle Jurassic). In the southern Danish Central Graben, the Middle Jurassic succession formerly referred to the Lower Graben Sand Formation is now included in the revised Bryne Formation. The Lulu Formation is erected to include the uppermost part of the Middle Jurassic succession, previously referred to the Bryne Formation in the northern Danish Central Graben. The Upper Jurassic Heno Formation is subdivided into two new members, the Gert Member (lower) and the Ravn Member (upper). The organic-rich part of the upper Farsund Formation, the former informal ‘hot unit’, is established formally as the Bo Member. Dominantly shallow marine and paralic deposition in the Late Triassic was succeeded by widespread deposition of offshore marine clays in the Early Jurassic. On Bornholm, coastal and paralic sedimentation prevailed. During maximum transgression in the Early Toarcian, sedimentation of organic-rich offshore clays took place in the Danish area. This depositional phase was terminated by a regional erosional event in early Middle Jurassic time, caused by uplift of the central North Sea area, including the Ringkøbing–Fyn High. In the Sorgenfrei–Tornquist Zone to the east, where slow subsidence continued, marine sandy sediments were deposited in response to the uplift. Uplift of the central North Sea area was followed by fault-controlled subsidence accompanied by fluvial and floodplain deposition during Middle Jurassic time. On Bornholm, deposition of lacustrine muds, fluvial sands and peats dominated. The late Middle Jurassic saw a gradual shift to shallow marine deposition in the Danish Central Graben, the Danish Basin and Skåne, southern Sweden. During the Late Jurassic, open marine shelf conditions prevailed with deposition of clay-dominated sediments while shallow marine sands were deposited on platform areas. The Central Graben received sand by means of sediment gravity flows. The clay sediments in the Central Graben became increasingly rich in organic matter at the Jurassic–Cretaceous transition, whilst shallow marine coarse-grained deposits prograded basinwards in the Sorgenfrei– Tornquist Zone.

A new parameter set for anisotropic multiparameter full-waveform inversion and application to a North Sea data set

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. U25-U38 ◽  
Author(s):  
Nuno V. da Silva ◽  
Andrew Ratcliffe ◽  
Vetle Vinje ◽  
Graham Conroy
Keyword(s):  
North Sea ◽  
Waveform Inversion ◽  
Real Data ◽  
Model Parameters ◽  
Full Waveform Inversion ◽  
Radiation Patterns ◽  
Data Set ◽  
Full Waveform ◽  
Seismic Image ◽  
Central North Sea

Parameterization lies at the center of anisotropic full-waveform inversion (FWI) with multiparameter updates. This is because FWI aims to update the long and short wavelengths of the perturbations. Thus, it is important that the parameterization accommodates this. Recently, there has been an intensive effort to determine the optimal parameterization, centering the fundamental discussion mainly on the analysis of radiation patterns for each one of these parameterizations, and aiming to determine which is best suited for multiparameter inversion. We have developed a new parameterization in the scope of FWI, based on the concept of kinematically equivalent media, as originally proposed in other areas of seismic data analysis. Our analysis is also based on radiation patterns, as well as the relation between the perturbation of this set of parameters and perturbation in traveltime. The radiation pattern reveals that this parameterization combines some of the characteristics of parameterizations with one velocity and two Thomsen’s parameters and parameterizations using two velocities and one Thomsen’s parameter. The study of perturbation of traveltime with perturbation of model parameters shows that the new parameterization is less ambiguous when relating these quantities in comparison with other more commonly used parameterizations. We have concluded that our new parameterization is well-suited for inverting diving waves, which are of paramount importance to carry out practical FWI successfully. We have demonstrated that the new parameterization produces good inversion results with synthetic and real data examples. In the latter case of the real data example from the Central North Sea, the inverted models show good agreement with the geologic structures, leading to an improvement of the seismic image and flatness of the common image gathers.

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