# Clyde oil field

The Clyde oil field is a crude oil producing field in the UK sector of the North Sea, 290 km east-south-east of Aberdeen. Production of oil started in 1987 and the field is still operational (2021).

## The field

The Clyde oil field is located in Block 30/17b of the UK North Sea continental shelf. It is named after the Scottish river. The Clyde field was discovered in 1978 and the oil reservoir comprises an Upper Jurassic sandstone at a depth of 10,000 feet (3,000 metres). The reservoir and its fluids has the following characteristics:
Clyde reservoir and fluids :
| Parameter | Value |
| Porosity | 0.23% |
| Permeability | 105 md |
| API gravity | 38.1°API |
| Gas Oil Ratio | 477 standard cubic feet/barrel |
| Sulfur content | 0.3% |
| Recoverable reserves | 154 million barrels, 17.7 million tonnes |

## Owners and operators

The initial owners of the field were Britoil (51%), Shell UK Ltd (24.5%) and Esso Petroleum Company Ltd (24.5%). Britoil was the operator. BP assumed ownership of Britoil assets in 1988. BP sold its interest in Clyde to Talisman in 1996. The company became Talisman Sinopec Energy, then Repsol Sinopec.

## Development

The Clyde field was developed by a single integrated drilling, production and accommodation platform. The principal design data of the Clyde platform is given in the following table.
Clyde platform design data :
| Coordinates | 56.452778N 2.288333E |
| Water depth, metres | 80 |
| Fabrication substructure | John Brown Earl & Wright |
| Jacket weight, tonnes | 12,300 |
| Topsides design | Humphreys & Glasgow |
| Topsides weight, tonnes | 17,259 |
| Function | Drilling, production, accommodation |
| Accommodation (crew) | 207 |
| Type | Steel jacket |
| Legs | 8 |
| Piles | 26 |
| Well slots | 30 (23 production, 5 water injection) |
| Throughput oil, barrels per day (bpd) | 60,000 |
| Water injection, bpd | 100,000 |
| Platform installed | Summer 1985, May 1986 |
| Production started | Late 1987 |
| Oil production to | Fulmar A by 9.85 km 16-inch pipeline |
| Gas production to | Fulmar A by 9.85 km 16-inch pipeline |

### Processing

Oil from the wellheads and subsea tie-ins is routed to the 1st stage 3-phase (oil, gas, water) separator. Oil then flows to the 2nd stage and 3rd stage separators operating at successively lower pressures. After metering the oil is pumped to the Fulmar A platform for storage and tanker loading.
Produced water from the separators is treated in a degassing vessel and hydrocyclones to an oil-in-water concentration of less than 30 ppm prior to discharge overboard.
Gas from the separators is compressed in the LP Compressor, Intermediate Pressure (IP) Compressor, HP Compressor and Export/Lift Compressor. There is also a gas dehydration plant. Gas in excess of that required for gas lift is exported to Fulmar A and then to the SEGAL system to St. Fergus terminal.
The fluid handling capability of the Clyde facilities in its latter years was as follows:
Clyde processing capability :
| Clyde process facility | Capacity |
| Crude oil export | 60,000 bpd |
| Gas dehydration | 42 MMSCFD |
| Produced water treatment | 97,000 bpd |
| Water injection | 73,000 bpd |

### Other fields

Several subsea fields are connected to Clyde through flowlines and pipelines. These fields include Leven, Medwin, Nethan, Orion, Cawdor and Flyndre. There are dedicated Separators on Clyde for the Orion and Flyndre fields. Data on these fields are as follows:
| Field | Cawdor | Flyndre | Leven | Medwin | Nethan | Orion |
| Block | 30/14 | 30/13 | 30/17b | 30/17b | 30/17 | 30/18 |
| Water depth, m | 70 | 70 | 86.9 | 75 | | |
| Reserves, million tonnes | 10.5 million barrels | 0.1 million Sm3 | 1.03 | 0.48 | | |
| Production start | | 2017 | 1992 | 1994 | 2004 | 1999 |
| Peak production, million tonnes per year | 5,000 bpd | 10,000 bpd | 0.24 | 0.18 | 13.1 ton th | |
| Pipeline | 20.46 km | 20 km 8.5-inch pipeline | | | | 16.3 km 10-inch pipeline |
The Flyndre field is located in the Norwegian sector of the North Sea. Production began in March 2017.