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, 150 miles east of Aberdeen. It is wholly owned by BG International Limited, which has been a part of the Shell Group companies since 2016.
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 Jackdaw reservoir 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. +Jackdaw reservoir propertiesPropertyValueFluid typeGas / gas condensateInitial reservoir pressure (psi at datum 5,174 m TVDss)17,158Initial reservoir temperature (°C)191Formation volume factor (cf/scf)0.002528 – 0.002759Dew point (psi)6,351 – 6,450Gas viscosity (cP) 0.051 – 0.0648Gas density (g/cm3)0.351 – 0.4293Gas condensate API gravity (°) 34.9 – 49Wax (% wt at -36 °C)17Wax appearance temperature (°C)46Asphaltene content (wt %)0Carbon dioxide (CO2) (mol %)4.2Hydrogen sulphide (H2S)(ppmv)30Mercury (Hg)(ng/m3 (gas))350Mercury (Hg) (μg/kg (condensate))15 The Jackdaw field is classified as an Ultra high pressure high temperature (uHPHT) field. Such fields are defined as having a reservoir pressure greater than 12,500 psi, and a temperature exceeding 166 °C.
Fluid production The Jackdaw wellhead platform (WHP) is a four-leg installation located at . 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 31 km 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.
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