| Jackdaw | |
| Coordinates: | 56°543.73N 2°2250.73E |
| Country: | United Kingdom |
| Region: | Central North Sea |
| Locblocks: | 30/02a, 30/02d, 30/03a |
| Owner: | BG International Limited |
| Operator: | Shell UK |
| Discovery: | 2005 |
| Production Gas Mmcuft/D: | 200 |
| Producingformations: | Upper Jurassic |
| Est Gas Ref: | 200 million barrels oil equivalent |
| Offonshore: | Offshore |
| Api: | 35 - 49 |
| Formations: | Heather |
Jackdaw gas field is a large offshore natural gas field which lies in Blocks 30/02a, 30/02d and 30/03a in the central North Sea,[1] 150 miles east of Aberdeen.[2] It is wholly owned by BG International Limited, which has been a part of the Shell Group companies since 2016.[3]
The Jackdaw field is being developed as a 'not permanently attended' platform in a water depth of 78 m, 30 km south east of the Shearwater installation to which fluids from Jackdaw are exported.
The reservoir is in the Upper Jurassic Heather Formation and is compartmentalised into two separate reservoir units. The properties of the reservoir and the fluids are as follows.[4]
| Fluid type | Gas / gas condensate | |
| Initial reservoir pressure (psi at datum 5,174 m TVDss) | 17,158 | |
| Initial reservoir temperature (°C) | 191 | |
| Formation volume factor (cf/scf) | 0.002528 – 0.002759 | |
| Dew point (psi) | 6,351 – 6,450 | |
| Gas viscosity (cP) | 0.051 – 0.0648 | |
| Gas density (g/cm3) | 0.351 – 0.4293 | |
| Gas condensate API gravity (°) | 34.9 – 49 | |
| Wax (% wt at -36 °C) | 17 | |
| Wax appearance temperature (°C) | 46 | |
| Asphaltene content (wt %) | 0 | |
| Carbon dioxide (CO2) (mol %) | 4.2 | |
| Hydrogen sulphide (H2S)(ppmv) | 30 | |
| Mercury (Hg)(ng/m3 (gas)) | 350 | |
| Mercury (Hg) (μg/kg (condensate)) | 15 |
The Jackdaw wellhead platform (WHP) is a four-leg installation located at 56.901°N 2.3808°W. The installation supports four wellheads. No hydrocarbon processing takes place on Jackdaw, the well fluids are sent to Shearwater for processing. The topsides pipework is rated for the full shut-in pressure of the wells. Transfer of fluids from Jackdaw to Shearwater is through a 31km long pipeline 12-inch internal diameter, 18-inch outside diameter pipe-in-pipe. A pipeline overpressure protection system (OPPS) protects the pipeline from the wellhead pressure.