Caister Murdoch System gas fields

The Caister Murdoch System (CMS) was a major natural gas collection, processing and transportation system in the UK sector of the southern North Sea. It comprised 11 platforms, 8 subsea wellhead completions and interconnecting pipelines centered about 155 km east of Flamborough Head Yorkshire. It operated from 1993 to 2018.

Background The Caister Murdoch System (CMS) was originally conceived by Conoco (U.K.) Ltd. and Total Oil Marine plc to develop the Murdock and Caister gas fields. Caister had been discovered by Total in Block 44/23 in January 1968 in Triassic Bunter Sands. However, its remote location near the UK / Netherlands median line meant there was no infrastructure to support the export of gas. The Caister Carboniferous gas field was discovered by Total in Block 44/23 in February 1985 and the Murdoch Carboniferous field by Conoco in Block 44/22 in August 1985. The discovery by Shell Oil of the Schooner Carboniferous gas field in Block 44/26 in December 1986 made the development of CMS viable.

The hub of the CMS was the Murdoch installation which initially comprised just the Murdoch MD platform. The Caister platform, installed in 1993, was an unmanned satellite. Production from MD began in October 1993 and was through the 188 km 26” pipeline to the Theddlethorpe gas terminal (TGT) in Lincolnshire. Conoco's Boulton field (1997) and Shell's Schooner and Ketch platforms were tied into the Murdoch system in 1996 and 1999 respectively. As wellhead pressures declined a compression platform Murdoch MC and an accommodation platform Murdoch MA were bridge linked to Murdoch MD. Other fields were tied in from 2000 to 2012.

List The locations, properties and late-life (2017) operatorship of gas fields tied into CMS were as follows. +CMS FieldsField and installationBlockCoordinatesWater depth, metresDiscoveredInitial licenseeOperator (2017)Boulton BM44/21a54.243611 2.32083342 1984ConocoConocoPhillipsBoulton HM44/2154.189297 2.21078136ConocoPhillipsConocoPhillipsCaister CM44/23a54.2.3809 2.45126941January 1968; February 1995TotalConocoPhillipsCavendish RM43/19a54.478744 1.740211181989BritoilIneosHawksley EM44/17a54.559028 2.491753172002ConocoConocoPhillipsHunter HK44/23a54.308500 2.420167341992, 2005CaledoniaPremierKaty KT44/19b54.403758 2.660611262012ConocoPhillipsConocoPhillipsKelvin TM44/18b54.336577 2.258694322005ConocoPhillipsConocoPhillipsKetch KA44/28b54.049417 2.488350511984ShellFaroe Petroleum (UK)McAdam MM44/1754.346472 2.357472322001Conoco, TullowConocoPhillipsMunro MH44/17b54.434625 2.300146272004TullowConocoPhillipsMurdoch K KM44/22a54.238186 2.38977538TullowConocoPhillipsMurdoch MD44/2254.268717 2.32376732August 1985ConocoConocoPhillipsMurdoch MC44/2254.268611 2.32388932––ConocoPhillipsMurdoch MA44/22a54.164250 2.19183930––ConocoPhillipsRita 44/22c54.277023 2.210656351996E.ON Ruhrgas UKPremierSchooner SA44/26a54.099033 2.07638373December 1986ShellFaroe Petroleum (UK)Topaz49/1a53.955167 2.827306342009RWE DeaIneosWatt QM44/22412001ConocoConocoPhillips

Names The names of gas fields in the area are derived from several themes.

18th and 19th century scientists, engineers and inventors: Matthew Boulton; Henry Cavendish; Thomas Hawksley; Hunter; Lord Kelvin; John McAdam; Munro; William Murdoch; James Watt. Sailing vessels: Ketch; Schooner. A Norfolk castle: Caister. Personal names: Katy, Rita. Gemstone: Topaz (cf. Amethyst gas field).

Developments The gas fields were developed through an array of platforms and subsea facilities. These were as shown in the following table, together with data on the peak rate and cumulative production of gas in million cubic metres (mcm).Conoco Gas Operations schematic Map (c. 2000) +CMS developments and productionInstallationStructureStart-upProduction toPipeline length and diameterPeak production, mcm/yYear of peakCumulative production to 2014, mcmBoulton BMSteel jacket1997Murdoch MD11 km, 10”92519987,185Boulton HMSubsea2002Watt QM1402004357Caister CMSteel jacket1993Murdoch MD11 km, 16”388 (Bunter)19953,202745 (Carboniferous)19955,156Cavendish RMSteel jacket2006Murdoch MD via Cavendish manifold47.2 km, 10”64920082,480Hawksley EMSubsea2002Murdoch MD via manifold22 km, 12”61020031,464Hunter HKSubsea2006Murdoch K KM6.2 km, 8”24200841Katy KTSteel 3-legs2012Kelvin TM–Murdock MD pipeline14 km, 10”2002013200Kelvin TMSteel 3-legs2007Murdoch MD via manifold12.5 km, 12”4572008738Ketch KASteel jacket1999Murdoch MD28 km, 18”1,23320006,407McAdam MMSubsea2003Hawksley–Murdoch pipeline92620063,691Munro MHSteel 3-legs2005Hawksley EM5 km, 10”35420061,379Murdoch K KMSubsea2002Murdoch MD via manifold5.5 km, 10”1,37820035,682Murdoch MDSteel jacket1993Theddlethorpe188 km, 26”1,063199413,606Murdoch MCSteel jacket1993Murdoch MD––––Murdoch MASteel jacket1993–––––Rita Subsea2009Hunter HK14 km, 8”50620101,086Schooner SASteel jacket1996Murdoch MD30 km, 16”1,24519978,659TopazSubsea2009Schooner SA 15.5 km, 6”942010198Watt QMSubsea2003Murdoch MD via manifold17 km, 10”16200416 In addition to the gas pipelines there was also a methanol distribution system. Methanol/corrosion inhibitor was pumped from TGT through a 4-inch pipeline to Murdoch MD. From here it was distributed to the platforms and wellheads through 3-inch and 2-inch pipelines.

New pipeline reception facilities and process plant was installed at TGT as part of the CMS development.

Production

Gas compression Wellhead gas from the individual fields was routed to either the Suction, the Interstage or the Discharge Manifold on Murdoch MC depending on its pressure.Murdoch Compression Flow scheme (undated) Gas from the Suction Manifold was routed to the Suction Slug Catcher where liquids were removed. Gas flowed successively to the LP Suction Scrubber, the First Stage Gas Compressor and the Intercooler. Here it was comingled with gas from the Interstage Manifold which had flowed through the Interstage Slug Catcher. The combined flow was routed to the Interstage Scrubber, the Second Stage Gas Compressor and the Export Gas Cooler. Gas was returned to the MD platform and to the Theddlethorpe trunk line. Recovered liquids were injected into the trunk line.

To increase the compression capacity a compressor module was added to the Murdoch MC platform in 2003.

Telecommunications Murdoch MD was connected to the Tampnet (formerly NorSea Com-1) submarine telecommunications cable system. It has landing points at Lowestoft, Suffolk, UK and Kårstø, Rogaland, Norway. It is connected to:

1. Draupner platform, operated by Gassco

2. Ula oil field, operated by BP

3. Ekofisk, operated by ConocoPhillips

4. Valhall oil field, operated by BP

5. Murdoch gas field, operated by ConocoPhillips (now disconnected)

Decommissioning Some CMS fields were shut-in in the 2010s when they became uneconomic to operate. Production from the CMS ceased with the shutdown of the Theddlethorpe gas terminal in August 2018. The platforms and subsea wellhead structures are being removed.

Caister Murdoch System gas fields

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