Haltenbanken region of the Norwegian Sea
The Heidrun oil and gas field is located 190km offshore in the Haltenbanken region of the Norwegian Sea in water depths of around 350m. The field comprised of two blocks, 6507/7 and 6507/8, covering an area of 38km².
Statoil is the operator of the field with a 12.41% interest. The other licensees of the field include Petoro (58.16%), ConocoPhillips (24.31%), and Eni (5.11%).
The production from the field during 2013 will be 65,000 barrels of oil per day and 760 million cubic metres of natural gas, according to the Norwegian Petroleum Directorate’s estimates.
Statoil and the partners are planning to maintain Heidrun in production until 2045 through additional developments on the field.
Consent was received for the use of a new satellite well (D-5 H) for processing on the Heidrun field in 2006. The production from the satellite well is expected by 2016.
The evaluation of new well targets at the field as well as the effort to upgrade the processing capacity is underway.
Odfjell drilling was awarded a contract for the drilling of new wells and plugging of old wells and drilling facilities at the Heidrun field in 2012.
The oilfield is also scheduled to have a permanent floating storage unit (FSU). Samsung Heavy Industries was awarded a $230m contract in September 2012 to deliver a new permanent floating storage unit (FSU) for the field.
The Heidrun field was discovered in 1985 and was brought on stream in October 1995.
The recoverable reserves at the field were originally estimated at 182.1 million cubic metres of oil, 46.5 billion cubic metres of gas, and 2.2 million tonnes of natural gas liquids (NGL). The remaining recoverable reserves from the field by the end of 2012 were estimated at 40.1 million cubic metres of oil, 31.3 billion cubic metres of gas and 1.7 million tonnes of NGL.
The Heidrun field situated in the Halten Terrace of the Mid-Norwegian Continental Shelf consists of sandstone reservoirs of four Jurassic age formations namely Garn, Ile, Tilje and Åre. The depth of the reservoir is up to 2,300m beneath the seabed.
The license to explore and appraise the offshore field was awarded to Conoco in 1984. The first discovery well was drilled in the same year, but failed to encounter any hydrocarbons column. The second well drilled in June 1985 encountered a 137m oil column. Seven more wells were drilled subsequently that confirmed a combined flow rate of up to 930m3 (6,000 barrels) of oil per day.
A 5,000km high resolution 3D seismic survey was carried out on the field in 1986, which provided detailed geologic and reservoir models.
The development approval for the field was received in 1991. In 1995, the Heidrun field commenced production with a floating concrete tension leg platform with 56 well slots.
Conoco was the operator of the field during the exploration and early development phase. The operatorship was taken over by Statoil with the start of production from the field.
The northern part of the field containing a recoverable reserve of 25 million barrels of oil was brought into production with installation of subsea facilities in 2000.
A water injection project was initiated at the field in 2001, under a contract awarded to the VM alliance comprised of Halliburton, Fabricom and Sørco. The project involved installation of two modules – one for injecting the sea water as well as produced water through three water injection pumps and the other for removing sulphur from injected sea water. The project was completed in 2003.
The Heidrun field is installed with world’s first ever floating concrete tension leg platform (TLP). The TLP is installed over a subsea template consisting of 56 well slots. The substructure of the platform comprises of concrete hull and module support beams (MSB). The topsides of the platform comprise of five main modules and a drilling rig.
The platform is anchored to four concrete foundations on the sea bed by 16 tubular steel tethers.
The oilfield currently has 51 production wells, 24 sea water injection wells, and one gas injection well.
The oil and gas are recovered from the field through pressure maintenance. The recovery strategy includes the use of water and gas injection as well as pressure depletion. The field has sea water injection capacity of 110,000 barrels a day.
The modular filtration plant for removing sulphur from sea injection water stands 27m high and weighs 970t. Sulphur is removed from the injection water to avoid plugging of the pipes and sub-surface formations.
The oil output of the Heidrun field is mainly transported via shuttle tankers to Statoil’s Mongstad terminal near Bergen. The oil is also supplied to Tetney in the UK.
The gas output is transported via pipeline to Tjeldbergodden in mid-Norway where Statoil’s methanol plant is located.
The Heidrun gas is also being supplied to Kårstø and further to Dornum in Germany via 1,400km trunkline as the field has been tied to Åsgard Transport from 2001 onwards.
The existing buoy loading system will be replaced by the new storage unit which will have a design life of 30 years. The new FSU will be permanently connected to a buoy. Crude oil output of the field will be loaded to the FSU vessel through subsea pipeline and underwater hoses. The oil will be lifted from the FSU vessel to shuttle tankers through offloading hose-strings.
The FSU unit as well as two shuttle tankers are being built at Samsung’s shipyard in Geoje Island, Korea. The FSU unit is scheduled to be delivered to the field in 2015.
Wärtsilä has been subcontracted to provide the inert gas systems for the Heidrun FSU. The company will also provide deep well pumps and fire water packages for the FSU.
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