The Davy, Bessemer, Beaufort and Brown Fields, Blocks 49/23, 49/30a, 49/30c, 53/5a, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 705-712 ◽  
Author(s):  
C. W. McCrone
Keyword(s):  
North Sea ◽  
Horizontal Well ◽  
Reservoir Quality ◽  
3D Seismic ◽  
Commercial Viability ◽  
Playa Lake ◽  
Technical Advances ◽  
Sandstone Formation ◽  
The Uk ◽  
Gas Fields

abstractDavy, Bessemer, Beaufort and Brown are a series of small to moderate (30-200 BCF) dry gas fields, which span the southeastern corner of the UK Southern North Sea Rotliegend Play fairway. Davy was discovered in 1970; however, it was not until 1989 that Bessemer and subsequently Beaufort in 1991 were drilled. These fields were developed and brought on-stream by Amoco licence groups in 1995/96. More recently the Brown Field was discovered in October 1998 with first gas seven weeks later. The commercial viability of these relatively small accumulations is the result of technical advances across several fronts: 3D seismic imaging, horizontal well technology and minimum offshore facilities.In the Bessemer and Beaufort area, the Rotliegend Leman Sandstone Formation reservoir (250 ft) primarily consists of stacked aeolian dune sandstones of good reservoir quality (porosity 17%, permeability 10-1000mD). However, in the Davy and Brown area there is greater variation in the Rotliegend isopach (300-700 ft) and the nature of facies present e.g., aeolian dune, sabkha and playa lake.The fields are tied back from the Bessemer and Davy mono-tower platforms via 15 km and 43 km pipelines, respectively, to the compression facilities on the Indefatigable 23AT platform.

The Sean fields, Block 49/25a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 255-261 ◽  
Author(s):  
R. J. Botman ◽  
J. van Lier
Keyword(s):  
North Sea ◽  
Reservoir Quality ◽  
Late Permian ◽  
High Recovery ◽  
Gas Field ◽  
Sandstone Formation ◽  
Gas Fields

AbstractBlock 49/25a contains the Sean gas fields, Sean North, Sean South and Sean East – collectively known as the Greater Sean area and discovered in 1969. The fields are located in the Southern Gas Basin, about 15 km SE of the Indefatigable gas field. Approximately 1.1 tcf of gas is trapped in a series of fault-bounded dip closures consisting of Permian sandstones belonging to the Leman Sandstone Formation (Rotliegend Group). The reservoir is overlain by evaporites of the Late Permian Zechstein Group. The fields are characterized by excellent Leman reservoir quality, and resources have increased significantly over the years. The reservoir largely behaves as a well-connected tank, which has resulted in high recovery factors (>90%).In 2015, Oranje-Nassau Energie UK Ltd (ONE) took over operatorship of the field through purchasing the rights of both Shell and Esso, giving ONE a 50% operated interest together with SSE E&P UK Ltd (SSE). In 2017, an infill well (SSPD05) was drilled by ONE to test a pop-up structure situated between Sean North and Sean South. The well found, as expected, partially depleted reservoir but has proven to accelerate production and add incremental reserves to the field.

The Malory Field, Block 48/12d, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 771-776
Author(s):  
R. E. O'Brien ◽  
M. Lappin ◽  
F. Komlosi ◽  
A. Loftus
Keyword(s):  
North Sea ◽  
Upper Permian ◽  
Reservoir Quality ◽  
Lower Permian ◽  
Burial Depth ◽  
Recoverable Reserves ◽  
Adjacent Structures ◽  
Sandstone Formation ◽  
The Uk ◽  
Hydrocarbon Charge

AbstractThe Malory Field straddles blocks 48/12d and 48/12c of the UK Sector of the Southern North Sea on the western margin of the Sole Pit Trough. The field is located within an upthrown part of the Dowsing Fault Zone and was discovered by the Mobil operated well 48/12d-9 in early 1997.The Malory Field is a small fault-bounded horst structure with expected recoverable reserves of 75 BSCF. The reservoir consists of a 249 ft-section of Lower Permian, Rotliegendes Leman Sandstone Formation sandstones, is sourced from the Carboniferous Westphalian Coal Measures below, and is sealed by overlying Upper Permian Zechstein evaporites.Reservoir quality is generally good with an average porosity of 14.7% and core permeabilities (Kh) between 0.2 and 1651 mD. This preservation of reservoir quality is attributed to a combination of the structure being located on a broad palaeostructural high, with a lower maximum burial depth than adjacent structures and associated lower compactional porosity loss, the presence of an early hydrocarbon charge and the preferential precipitation of chlorite over illite cements.

The Indefatigable Field, Blocks 49/18, 49/19, 49/23, 49/24, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 741-747 ◽  
Author(s):  
C. W. McCrone ◽  
M. Gainski ◽  
P. J. Lumsden
Keyword(s):  
North Sea ◽  
Seismic Survey ◽  
3D Seismic ◽  
Gas Field ◽  
Recoverable Reserves ◽  
Phases Of Development ◽  
Four Blocks ◽  
Sandstone Formation ◽  
Well Data ◽  
The Uk

abstractIndefatigable is a mature dry gas field on the northeastern margin of the UK Southern North Sea Rotliegend Play fairway. The field was discovered, 49/18-1, by the Amoco operated group in 1966 and subsequent appraisal drilling established that the field extended over four blocks (i.e. 49/18, 49/19, 49/23 & 49/24). There have been several phases of development, initial production concentrated on the main horst block with first gas in 1971, followed by the west flank area in 1977/78. Then in 1987/88 the SW and SE Indefatigable satellite accumulations were brought on-stream.The Rotliegend Leman Sandstone Formation reservoir primarily consists of stacked aeolian dune sandstones (150-400 ft) of good reservoir quality (porosity 15%, permeability 100-1000 mD). However, the integration of the 1992/93 3D seismic survey, well data, reservoir pressure and production data has lead to a much more complex view of the field with 11 gas-water contacts and 15 reservoir compartments.This has resulted in an upward revision of the gas initially-in-place from 5.2 to 5.6 TCF and recoverable reserves from 4.4 to 4.7 TCF. Current work is focused on maximizing recovery from the various reservoir compartments and accessing this additional potential.

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 Hewett Field satellites: Big Dotty, Little Dotty, Deborah, Della, Dawn and Delilah, Blocks 48/29a, 48/30a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 203-216 ◽  
Author(s):  
J. A. Hook
Keyword(s):  
Fault Zone ◽  
North Sea ◽  
The Other ◽  
Reservoir Quality ◽  
Marked Contrast ◽  
Strategic Role ◽  
Sandstone Formation ◽  
Water Cut

AbstractSix satellite fields have been developed through the Hewett Field facilities: Big Dotty, Little Dotty, Deborah, Della, Dawn and Delilah. Little Dotty has produced from both the Leman Sandstone Formation (LSF) and Bunter Sandstone Formation (BSF) whilst the other satellites are exclusively LSF developments. The LSF reservoir quality exhibits a marked contrast across the Dowsing Fault Zone, which separates the inboard satellites to the SW from the outboard satellites to the NE. The inboard satellites, Big Dotty, Little Dotty and Dawn, display the best reservoir quality, reflecting their lesser depth of maximum burial. These fields share a strong aquifer, exhibited a rapid water-cut development and are now shut-in. The greater depth of maximum burial experienced by the outboard satellites, Deborah, Della and Delilah, is reflected in poorer reservoir quality along with weaker aquifers that are also more compartmentalized. These remain in production and will achieve higher recovery factors. Big Dotty was developed from a wellhead platform whereas the other fields were developed as subsea tie-backs. Collectively, these satellite fields have produced some 0.9 tcf of gas, playing an important strategic role in offsetting the production decline in the Hewett Field and extending the life of the asset.

The Machar Field, Block 23/26a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 523-536 ◽  
Author(s):  
Zoë Sayer ◽  
Jonathan Edet ◽  
Rob Gooder ◽  
Alexandra Love
Keyword(s):  
North Sea ◽  
Debris Flows ◽  
Water Injection ◽  
Salt Diapir ◽  
Reservoir Quality ◽  
Complex Interplay ◽  
Light Oil ◽  
High Matrix ◽  
The Uk ◽  
Central North Sea

AbstractMachar is one of several diapir fields located in the Eastern Trough of the UK Central North Sea. It contains light oil in fractured Cretaceous–Danian chalk and Paleocene sandstones draped over and around a tall, steeply-dipping salt diapir that had expressed seafloor relief during chalk deposition. The reservoir geology represents a complex interplay of sedimentology and evolving structure, with slope-related redeposition of both the chalk and sandstone reservoirs affecting distribution and reservoir quality. The best reservoir quality occurs in resedimented chalk (debris flows) and high-density turbidite sandstones. Mapping and characterizing the different facies present has been key to reservoir understanding.The field has been developed by water injection, with conventional sweep in the sandstones and imbibition drive in the chalk. Although the chalk has high matrix microporosity, permeability is typically less than 2 mD, and fractures are essential for achieving high flow rates; test permeabilities can be up to 1500 mD. The next phase of development is blowdown, where water injection is stopped and the field allowed to depressurize. This commenced in February 2018.

The Hewett Field, Blocks 48/28a, 48/29a, 48/30a, 52/4a and 52/5a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 189-202 ◽  
Author(s):  
J. A. Hook
Keyword(s):  
Fault Zone ◽  
North Sea ◽  
Structural Evolution ◽  
Field Development ◽  
Southern North Sea ◽  
Sandstone Formation ◽  
The Uk ◽  
Basin Margin ◽  
Sour Gas

AbstractThe Hewett Field has been in production for some 50 years. Unusually for a Southern North Sea field in the UK Sector, there has been production from several different reservoirs and almost entirely from intervals younger than the principal Leman Sandstone Formation (LSF) reservoir in the basin. Some of these reservoirs are particular to the Hewett area. This reflects the location of the field at the basin margin bound by the Dowsing Fault Zone, which has influenced structural evolution, deposition and the migration of hydrocarbons. The principal reservoirs are the Permo-Triassic Hewett Sandstone (Lower Bunter), Triassic Bunter Sandstone Formation (BSF) (Upper Bunter) and Permian Zechsteinkalk Formation. There has also been minor production from the Permian Plattendolomit Formation and the LSF. Sour gas is present in the BSF only. Several phases of field development are recognized, ultimately comprising three wellhead platforms with production from 35 wells. Gas is exported onshore to Bacton, where the sour gas was also processed. Peak production was in 1976 and c. 3.5 tcf of gas has been recovered. Hewett has also provided the hub for six satellite fields which have produced a further 0.9 tcf of gas. It is expected that the asset will cease production in 2020.

The Osprey Field, Blocks 211/18a & 211/23a, UK North Sea*

1991 ◽  
Vol 14 (1) ◽  
pp. 183-189 ◽  
Author(s):  
John W. Erickson ◽  
C. D. Van Panhuys
Keyword(s):  
Crude Oil ◽  
North Sea ◽  
Water Depth ◽  
Middle Jurassic ◽  
Reservoir Quality ◽  
Shetland Islands ◽  
Delta System ◽  
Reservoir Sandstones ◽  
Northern North Sea ◽  
The Uk

AbstractThe Osprey Oilfield is located 180 km northeast of the Shetland Islands in Blocks 211/23a and 211/18a in the UK sector of the northern North Sea. The discovery well 211/23-3 was drilled in January 1974 in a water depth of 530 ft. The trap is defined at around 8500 ft TVSS by two dip and fault closed structures, the main 'Horst Block' and the satellite 'Western Pool'. The hydrocarbons are contained in reservoir sandstones belonging to the Middle Jurassic Brent Group which was deposited by a wave-dominated delta system in the East Shetlands Basin. The expected STOIIP and ultimate recovery are estimated at 158 MMBBL and 60 MMBBL of oil respectively, which represents a recovery factor of 38%. The 'Horst Block' contains 85% of the reserves with an OOWC about 150 ft shallower than in the 'Western Pool'. Reservoir quality is excellent, with average porosities varying from 23-26% and average permeabilities varying from 35-5300 md. The development plan envisages eleven satellite wells, six producers and five water injectors, closely clustered around two subsea manifolds. First production is expected in late 1990/early 1991. The wet crude oil will be piped to the Dunlin 'A' platform for processing and from there to the Cormorant Alpha platform into the Brent System pipeline for export to the Sullom Voe terminal.

Ravenspurn South Field, Blocks 42/29, 42/30, 43/26, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 469-475 ◽  
Author(s):  
R. D. Heinrich
Keyword(s):  
North Sea ◽  
Reservoir Quality ◽  
Desert Environment ◽  
Gas Field ◽  
Field Development ◽  
Southern North Sea ◽  
Fluvial Processes ◽  
Sandstone Formation ◽  
Aeolian Sands

AbstractThe Ravenspurn South Gas Field is located in the Sole Pit Basin of the Southern North Sea in UKCS Block 42/30, extending into Blocks 42/29 and 43/26. The gas is trapped in sandstones of the Permian Lower Leman Sandstone Formation, which was deposited by aeolian and fluvial processes in a desert environment. Reservoir quality is poor, and variations are mostly facies-controlled. The best reservoir quality occurs in aeolian sands wth porosities of up to 23% and permeabilities up to 90 md. The trap is a NW-SE-striking faulted anticline: top seal is provided by the Silverpit Shales directly overlying the reservoir, and by Zechstein halites. Field development began early in 1988 and first gas was delivered in October 1989. Production is in tandem with the Cleeton Field, about 5 miles southwest of Ravenspurn South, as the Villages project. Initial reserves are 700 BCF and field life is expected to be 20 years.

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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