The Ivanhoe and Rob Roy Fields, Blocks 15/21a-b, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 331-338 ◽  
Author(s):  
R. H. Parker
Keyword(s):  
North Sea ◽  
Upper Jurassic ◽  
Rock Properties ◽  
Production Facility ◽  
Injection Wells ◽  
Recoverable Reserves ◽  
Fault Block ◽  
Moray Firth ◽  
Sandstone Formation ◽  
Northeast Coast

AbstractThe Ivanhoe and Rob Roy Fields are located in the Outer Moray Firth Basin, seventy nautical miles off the northeast coast of Scotland. The Ivanhoe Field was discovered in 1975, and the Rob Roy Field in 1984. The reserves in both fields occur in tilted fault block traps of Upper Jurassic, Piper Sandstone Formation. Estimated total recoverable reserves amount to 100 MMBBL and 62 BCF. The fields are separated by a water corridor approximately 1 km wide. Both fields contain two reservoir sandstone units, an upper and lower, locally termed the Supra Piper Sandstone and Main Piper Sandstone respectively. The reservoirs in both fields exhibit excellent rock' properties with porosities up to 28% and permeabilities of several Darcies.Each field is developed via a subsea manifold surrounded by a cluster of production and injection wells, of which two were pre-drilled on Ivanhoe and six pre-drilled on Rob Roy. This allowed rapid achievement of the 60 000 BOPD plateau oil production rate soon after commissioning of facilities in July 1989. The two subsea manifolds are tied into a single subsea production manifold which connects with a Floating Production Facility. Crude oil is exported to the Claymore A Platform and gas to the Tartan A Platform.

The Victor Field, Blocks 49/17, 49/22, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 503-508 ◽  
Author(s):  
Robert A. Lambert
Keyword(s):  
North Sea ◽  
Early Permian ◽  
Gas Field ◽  
Eastern Flank ◽  
Southern North Sea ◽  
Recoverable Reserves ◽  
Fault Block ◽  
Sandstone Formation

AbstractThe Victor gas field lies in the Southern North Sea Gas Province on the eastern flank of the Sole Pit Basin. The field straddles Blocks 49/17 and 49/22, and is situated approximately 140 km off the Lincolnshire coast. Victor was discovered in April 1972 and is operated by Conoco (UK) Ltd on behalf of BP, Mobil and Statoil. The structure is an elongated tilted fault block, trending NW-SE. The reservoir sands are contained in the Leman Sandstone Formation (Rotliegendes Group) of Early Permian age, and consist mainly of stacked aeolian and fluvial sands with a gross thickness of 400-450 ft across the field. Porosities vary from 16-20%, with permeabilities ranging from 10 md to 1000 md in the producing zones. Initial gas in place is estimated at about 1.1 TCF with recoverable reserves of the order of 900 BCF. The field was brought on-stream in October 1984, and the five producing wells deliver, on average, 200 MMSCFD through the Viking Field 'B Complex' to the Conoco/BP terminal at Theddlethorpe in Lincolnshire

The Balmoral Field, Block 16/21, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 237-244 ◽  
Author(s):  
P. C. Tonkin ◽  
A. R. Fraser
Keyword(s):  
North Sea ◽  
Reservoir Pressure ◽  
Production Facility ◽  
Lower Section ◽  
Submarine Fan ◽  
The North ◽  
Recoverable Reserves ◽  
The North Sea ◽  
Structural High ◽  
Northeast Coast

AbstractThe Balmoral oilfield operated by Sun Oil Britain Ltd, lies within UK blocks 16/21 b and 16/21c, 140 miles off the northeast coast of Scotland. The field was discovered by the drilling of well 16/21-1 in 1975. Andrew Formation sandstones of Late Palaeocene age form the reservoir, which is sealed by Lista Formation claystones. The sandstones are of submarine fan origin sourced from the north and west of the area. The trap is structural, formed by the differential compaction of Tertiary sediments over a Palaeozoic structural high.The upper section of the reservoir consists of two units of consolidated sandstone (units U and M) of channel-fill origin separated by a channel abandonment claystone (unit SI). Porosities for these sandstone units range from 17-28% and permeabilities are up to 3300 md. The lower section of the reservoir consists of friable sandstones (Unit F), characterized by grain-coating clays which have prevented consolidation. This unit is mainly of submarine fan lobe origin. Porosities range from 20-28% and permeabilities are up to 700 md.Balmoral came on stream in November 1986. Recoverable reserves are estimated to be 68 MMBBL of undersaturated 39.9° API oil, and annual production remains at the 35 000 BOPD plateau rate.The oil is produced from 12 wells with reservoir pressure maintained by the injection of water through a further six wells. These are all tied into a floating production vessel (FPV), the first such purpose-built production facility to be used in the North Sea. Production in Balmoral is expected to continue until the year 2001.

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.

The Buchan Field, Blocks 20/5a and 21/1a, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 253-259 ◽  
Author(s):  
C. W. Edwards
Keyword(s):  
North Sea ◽  
Upper Jurassic ◽  
Hydrocarbon Migration ◽  
Red Sandstone ◽  
Recoverable Reserves ◽  
Fault Block ◽  
Southern Side ◽  
The Witch ◽  
The Uk ◽  
Sandstone Facies

AbstractThe Buchan Oilfield is located in Blocks 21/la and 20/5a of the UK North Sea, on the southern side of the Witch Ground Graben. The Buchan structure is a complex tilted and dissected fault block formed during Jurassic extension and rifting. The Upper Devonian-Carboniferous reservoir is composed of fluvial Old Red Sandstone facies sandstones sealed by Lower Cretaceous mudstones and contains a 585m (1919 ft) thick oil column. Poor matrix porosities and permeabilities are enhanced by a pervasive fracture system, although faulting in the reservoir restricts communication between several of the nine producing wells. Hydrocarbon migration has occurred from a mature Upper Jurassic source rock north of the field into the structure across the flank faults. Production of the highly under-saturated oil is by depletion drive with some aquifer sweep to a floating production facility and onward transmission to the Forties Field by pipeline. Production commenced in 1981 and original recoverable reserves are estimated at 90 MMBBL of which 71.5 MMBBL have already been produced.

The Clipper Field, Blocks 48/19a, 48/19c, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 691-698
Author(s):  
M. J. Sarginson
Keyword(s):  
North Sea ◽  
Upper Permian ◽  
Lower Permian ◽  
Reservoir Properties ◽  
Gas Field ◽  
Field Development ◽  
Matrix Permeability ◽  
Recoverable Reserves ◽  
Reservoir Permeability ◽  
Sandstone Formation

AbstractThe Clipper Gas Field is a moderate-sized faulted anticlinal trap located in Blocks 48/19a, 48/19c and 48/20a within the Sole Pit area of the southern North Sea Gas Basin. The reservoir is formed by the Lower Permian Leman Sandstone Formation, lying between truncated Westphalian Coal Measures and the Upper Permian evaporitic Zechstein Group which form source and seal respectively. Reservoir permeability is very low, mainly as a result of compaction and diagenesis which accompanied deep burial of the Sole Pit Trough, a sub basin within the main gas basin. The Leman Sandstone Formation is on average about 715 ft thick, laterally heterogeneous and zoned vertically with the best reservoir properties located in the middle of the formation. Porosity is fair with a field average of 11.1%. Matrix permeability, however, is less than one millidarcy on average. Well productivity depends on intersecting open natural fractures or permeable streaks within aeolian dune slipface sandstones. Field development started in 1988. 24 development wells have been drilled to date. Expected recoverable reserves are 753 BCF.

The Amethyst Field, Blocks 47/8a, 47/9a, 47/13a, 47/14a, 47,15a, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 387-393 ◽  
Author(s):  
C. R. Garland
Keyword(s):  
North Sea ◽  
Reservoir Quality ◽  
Geological Model ◽  
Gas Field ◽  
Seismic Parameters ◽  
Recoverable Reserves ◽  
High Production ◽  
Sandstone Formation ◽  
Phased Development ◽  
Overlying Strata

AbstractThe Amethyst gas field was discovered in 1970 by well 47/13-1. Subsequently it was appraised and delineated by 17 wells. It consists of at least five accumulations with modest vertical relief, the reservoir being thin aeolian and fluviatile sandstones of the Lower Leman Sandstone Formation. Reservoir quality varies from poor to good, high production rates being attained from the aeolian sandstones. Seismic interpretation has involved, in addition to conventional methods, the mapping of several seismic parameters, and a geological model for the velocity distribution in overlying strata.Gas in place is currently estimated at 1100 BCF, with recoverable reserves of 844 BCF. The phased development plan envisages 20 development wells drilled from four platforms, and first gas from the 'A' platforms was delivered in October 1990. A unitization agreement is in force between the nine partners, with a technical redetermination of equity scheduled to commence in 1991.

The Gawain Field, Blocks 49/24, 49/29a, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 713-722
Author(s):  
R. A. Osbon ◽  
O. C. Werngren ◽  
A. Kyei ◽  
D. Manley ◽  
J. Six
Keyword(s):  
North Sea ◽  
Early Permian ◽  
Water Contact ◽  
Field Development ◽  
Dune Sands ◽  
Southern North Sea ◽  
Recoverable Reserves ◽  
Structural Relief ◽  
Sandstone Formation

AbstractThe Gawain Field is located on the Inde shelf in the Southern North Sea, 85 km NE of the Norfolk coast. Gawain was discovered in 1970 by well 49/29-1 and a total of nine wells have been drilled on the structure. Gas is produced from the Leman Sandstone Formation of Early Permian age. The reservoir section is comprised predominantly of stacked aeolian dune sands possessing excellent poroperm characteristics. The structure is a complex NW-SE trending horst block with a common gas-water contact at 8904 ft TVDss. Low structural relief has presented a major challenge to field development, which has utilized extended reach wells to maximize drainage potential. Initial gas-in-place is estimated at 289 BCF with recoverable reserves in the order of 196 BCF. The field came on production in September 1995 via a sub-sea tie back to the Thames infrastructure and has an expected field life of 10 years

The South Brae Field, Block 16/7a, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Martin J. Roberts
Keyword(s):  
North Sea ◽  
Oil Production ◽  
Upper Jurassic ◽  
The Other ◽  
Field Margins ◽  
The South ◽  
Western Margin ◽  
Recoverable Reserves ◽  
Clay Formation ◽  
Devonian Age

AbstractSouth Brae Oilfield lies at the western margin of the South Viking Graben, 161 miles northeast of Aberdeen. Oil production began in July 1983 from a single platform located in 368 ft of water. The field originally contained 312 MMBBL of recoverable reserves, and in May 1990, cumulative exports of oil and NGL reached 219 MMBBL. The reservoir lies at depths in excess of 11800 ft TVSS, has a maximum gross hydrocarbon column of 1670 ft, and covers an area of approximately 6000 acres.The reservoir is the Upper Jurassic Brae Formation which is downfaulted against tight sealing rocks of probable Devonian age at the western margin of the field. The other field margins are constrained by a combination of structural dip and stratigraphic pinchout.The reservoir is capped by the Kimmeridge Clay Formation, which is also the source of the oil.

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 Cygnus Field, Blocks 44/11a and 44/12a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 151-162 ◽  
Author(s):  
Ian Dredge ◽  
Gary Marsden
Keyword(s):  
North Sea ◽  
Horizontal Wells ◽  
Third Party ◽  
Production Well ◽  
Field Development ◽  
Fault Block ◽  
Main Fault ◽  
Sandstone Formation ◽  
The Uk ◽  
Gas Bearing

AbstractThe Cygnus Field is located in Blocks 44/11a and 44/12a of the UK Southern North Sea. The field was first discovered in 1988 as a tight lower Leman Sandstone Formation gas discovery by well 44/12- 1. After the licences had sat idle for several years, GDF Britain (now Neptune E&P UK Ltd) appraised the field from 2006 to 2010. During the appraisal phase, the lower Leman Sandstone was found to be of better quality than first discovered and the gas-bearing lower Ketch Member reservoir was also encountered. The field development was sanctioned in 2012.The field has been developed from two wellhead platforms targeting Leman Sandstone and Ketch Member reservoirs. Five main fault blocks have been developed, with two wells in each fault block planned in the field development plan. The wells are long horizontal wells completed with stand-alone sand screens. At the time of writing, the production plateau is 320 MMscfgd (266 MMscfgd when third-party constraints apply), producing from nine wells with the final production well to be drilled.

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