Central North Sea
The Jacky field is located in block 12 / 21c in the UK Continental Shelf, in water depths of 30-40m, 19km east of the Moray Firth Caithness cliffs. It was discovered in April 2007 and development approval was granted by the UK authorities in November 2008.
Jacky is owned by Ithaca Energy (67.275% and operator), Dyas (22.725%) and North Sea Energy (10%).
The Jacky reservoir occurs in the Beatrice A sands, a mid-Jurassic sandstone formation just over 2,000m below the surface.
Reservoir pressure is low and the temperature of the reservoir’s fluid is about 85°C.
The oil is sweet, waxy and, at 38.9° API, relatively light. It also has a low gas-oil ratio, so there is no significant production and, therefore, no exports of gas.
Gross proven and probable reserves are put at 5.1 million barrels, giving the field a predicted economic life of up to 5.5 years.
The capital cost of the project was originally estimated at £59.7m, but shifts in exchange rates have meant the final figure is likely to rise by 20-24%.
The Jacky field is being developed in phases. The first phase consisted of installing a single production well, using the Ensco 92 jack-up drilling rig, tied in through a normally unmanned and removable wellhead platform. The platform, which was installed using the Hermod lift barge, was fixed to the seabed using removable suction piles.
Also in phase I, a 6in insulated oil pipeline, an 8in water injection pipeline and a power cable and control umbilical, all 10.5km long, were laid from the Jacky platform to the existing Alpha processing facility in the nearby Beatrice field, which is owned by Ithaca (74.75%) and Dyas (25.25%).
In addition, a small manifold was installed to enable connections for two short pipelines to the Beatrice Bravo satellite platform for potential future use. Ithaca has also restarted production from Beatrice Bravo, which was delivering approximately 800bpd when it was shut in by the previous owners of the field in July 2007.
Jacky started producing in early April 2009 and by May that year was flowing without artificial lift at gross rates of about 8,800bpd. Ithaca says that this compares favourably with predevelopment expectations that artificial lift would be required to achieve 7,800bpd gross.
As of early May 2009, the intention was to allow the reservoir pressure to fall so that artificial lift would happen.
Phase II of the development includes drilling and completion of a second production well and a water injection well. Both wells will be drilled via slots on the Jacky platform.
In March 2011, Ithaca initiated drilling of the second production well at the field. Named 12 / 21c-J03, the well is being drilled by the Energy Enhancer jack-up rig in the northern area of the field.
All processing takes place on Beatrice Alpha. Two parallel oil production trains are sized to process 50,000bpd of wellhead fluids while a test train, which allows individual testing of wells, can process up to an extra 25,000bpd.
Produced gas is flashed off in the separators and handled by flare systems. The process system is designed to remove free water below 30ppm oil in water.
Processing oil, along with 50% water, is exported through a 16in pipeline to the Nigg oil terminal in the Cromarty Firth. Nigg is held 74.75% by Ithaca and 25.25% by Dyas.
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