Harding oilfield
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The Harding oilfield is a small field operated by BP, in the mid North Sea, approximately 200 miles North-East of Aberdeen.
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[edit] Discovery and development
It was discovered in 1987 with oil located in the Eocene, though the abundance of napthalmic acid made its oil unattractive at the time. The oil from the Harding field requires a form of offshore storage. This is because the crude is heavy and naphthenic and therefore is generally of a lower value compared to some other North Sea crudes. Consequently the decision was made to export it by tanker rather than co-mingle it in a pipeline. A number of options were considered for the development and the final solution was a heavy duty steel jack-up production unit, based on a proprietary design by Technip Geoproduction resting on a concrete gravity base/storage tank, capable of holding 550,000 barrels of oil.
[edit] Reservoir
The Harding field is in fact composed of five separate reservoirs. The largest is the central field, hosting most of the wells as well as the site of the gas re-injection. There is also smaller fields to the North, North-East, South and South-East, all named as such. This has led to a unique well naming system in addition to the traditional use of DTI well numbers and slot numbers, which identifies a well by the particular field in which it has been drilled and its purpose.
The formations are unconsolidated, making the wells likely to produce sand. In order to prevent this, traditional cased hole completions are not used on any of the Harding wells. Instead, all wells used sandscreens.
[edit] Production
Harding presently produces around 25 mbd, from 15 wells, and 9mmscfd (9,000,000 scfd), most of which is re-injected. All production wells are gas lifted. The central reservoir is supported by two water injection wells and a gas injector. The south and north fields have the support of one water injector each, though the injector in the north field is currently suspended.
All produced water is reinjected. In addition there are two aquifer wells to provide extra injection water, if required.
Without a pipeline, the bulk of the produced gas has been reinjected into the cap of the central reservoir, sequestering it for production after 2009, when the platform is converted to a gas producer after decline of oil production.
[edit] Harding Area Gas Project
The Harding reservoir also contains gas, which BP hopes to develop at some stage. BP announced plans in 2006 to develop the gas resources via the Harding Area Gas Project. A combination of factors has made this original development concept uncompetitive – particularly low gas prices and increased development costs. The project is being recycled and BP is in discussion with its partner, Maersk, to investigate alternative development options for the gas resources in the area.
