Valhall

Valhall is a giant oilfield in the southern Norwegian North Sea. Production started in 1982 and following commissioning of the new PH platform in 2013 the field now has the potential to continue producing for several decades. Whilst significant quantities of oil and gas remain technically recoverable, much of this has marginal economics today and continuous technological innovation and efficiency improvements will be required to unlock the future potential of Valhall.

From May to October 2015 extensive surface preparation and paint work was executed on Valhall field center and flank platforms. The work also included the necessary structural maintenance on the older platforms that will be removed in a few years and on the injection platform, the wellhead platform and the combined production and hotel platform. In 2015 the supplementing work following the completion of the Valhall re- development project was accomplished, this makes Valhall operate with a closed flare during normal operation.

Development

Valhall is an oil field located in 70 metres of water. The field was originally developed with three facilities, but has now 8 platforms. 

The Valhall complex consists today of six separate steel platforms for quarters, drilling, wellheads, production, water injection, combined process- and hotel platform respectively. These platforms are bridge-connected. In addition the field has two unmanned flank platforms, one in the south and one in the north, both around  6 kilometers from the field center. 

Valhall is also the owner of the 2/4 G-platform installed in 1982, located at Ekofisk and operated by Conoco Phillips. The platform was taken out of service as part of Ekofisk II in 1998. Both the removal and impact assessment plan was approved by the Ministry of Petroleum and Energy in December 2015

The Quarters Platform (QP)

Built in 1979 and put to use in July 1981. It has accommodations for 208 people but due to subsidence and air gap requirements between cellar deck and sea level only maximum 177 people are allowed to be accommodated. During periods of extreme weather the manning level on QP are further regulated according to procedures agreed with the authorities. 
QP will be closed for the winter season: 1st November 2015  until 31st March 2016 and from 1st November 2016 until 31st March 2017.  The QP installation will be permanently shut in during 3Q 2017 at the latest. 

The Drilling Platform (DP) -plug and abandonment of wells

Situated between QP and PCP. It has 30 well slots, waste injection and a drilling rig. The platform started its activity on 17 December 1981, at that time with the first covered derrick. The derrick and drilling foundation were removed during summer 2009. A  separate program for plug and abandonment commenced during 2014 using the Maersk Reacher HDJU.  
Since start up, six wells have been plugged and completed 273 days ahead of schedule as per end of 2015. A total of 31 wells shall be permanently plugged. The work was originally estimated to take 10 years, however, if the good progress continues, it is possible to complete the work several years earlier. The drilling rig leaves Valhall in August 2016 and will be replaced by the new Maersk XLE 4 rig in the second quarter of 2017.

The Production Platform (PCP)

The final shut in of the platform took place late July 2012 and the production now takes place on the new process and hotel platform The original PCP platform was built to process 168,000 barrels of oil and 350 million cubic feet of gas per day. The platform is 65 meters high and weighs 21,000 tons. The oil production is piped to 2/4-J at the Ekofisk Center and goes to Teesside in England. The gas is transported directly via Norpipe pipeline to Emden in Germany. The platform also processes oil and gas that comes from Hod.

Export solution

The oil is exported through a pipeline via Ekofisk to Teeside. The gas is routed via the Norpipe pipeline to Emden.

The Wellhead Platform (WP)

Installed in April 1996 and first oil production started in June the same year. WP has 19 well slots. 

The Drilling and Water Injection Platform (IP)

IP is a fixed steel platform, bridge linked to the existing Valhall wellhead platform. The platform was installed in 2003 and the first water injection took place January 2004. It has integrated topsides with water injection facilities, seawater treatment facilities and a platform -based drilling rig, which can skid on beams from IP to WP. The platform configuration allows for drilling and maintenance of wells on the new platform (24 wells total) and on the existing WP platform (19 wells total). To date 8 water injection wells have been drilled from IP.  
State-of-the-art automated drilling rig which through a fiber optic line is linked into an Onshore Operations Center in Stavanger, 
The IP drilling rig has been engaged in a programme of infill drilling and workovers. 
The drilling pause on the injection platform which started in 1 Q 2015 is expected to last until end 2016 and recertification of the drilling unit will be completed June/July 2016.
Water injection is important for extraction of oil from Valhall. The water supply contributes to uphold the pressure in the reservoir hence keep stable production from the chalk field. Technical analyses of the system and change out of equipment have resulted in stable water injection at Valhall.

Valhall Crestal Gas Lift Project has been completed and a total of 9 wells can produce with extra support from gas lift which improves the  production from Valhall. The project involved significant modifications to both IP and WP to start gas injection and improve recovery from the central area of the reservoir. 

The Valhall Flank Platforms

These are two identical unmanned wellhead platforms each equipped with 16 drilling slots and located about 6 km (one to the North and one to the South) from the existing Valhall Facilities where well streams are processed. The Flank drilling programme using the Maersk Reacher HDJU was  completed around mid year 2014 and the rig moved to DP to commence well plugging and abandonment activities.  During 2014 the Valhall Flank gas lift project was completed and this help to reduce the rate of production decline from the flank wells. 
The South Flank started production 8th May 2003. While the North Flank came on stream 7th January 2004.

Production and Hotel Platform (PH)

The new Process/Hotel Platform (PH) is mounted on a 108m high fixed steel jacket and connected to the other installations via an external system of bridges and walkways. It contains all essential utilities/process piping, linking PH to the existing complex . The platform has new pipeline (subsea) crossovers to and from the new PH platform. It is powered from shore via a 78mw power cable from Lista. The platform has an integrated operating environment linking onshore and offshore personnel.

Some other key facts about the new combined production and hotel platform:
  • New facility design life: 40 years
  • Accommodation: 180 single bed cabins
  • Oil production capacity: 120,000 bpd
  • Gas handling capacity: 143 mmscf/d
  • Topsides (dry) weight: 18,500 tonnes
  • Jacket substructure: 8,400 tonnes
  • Power from shore: 294 km direct-current cable from southern Norway
Block and prod. licence:   
2/8 - prod. licence 006, 
awarded 1965
2/8 - prod. licence 006B, 
awarded 2000
2/11 - prod. licence 033B, 
awarded 2001
Discovered: 1975
On stream in: 1982
Licensees:
BP Norge AS 35.953125%
Hess Norge AS 64.046875% 
License period: 2028
Reservoir rock:  Chalk
Reserves at sanction  247 million barrels 
(435 mm boe)
Remaining resources 01.01.2016:
Oil: 231.5 million bbl
Sales Gas: 5.680 billion sm3



Oil: 33.4 mstb/d
NGL: 1.5 mstb/d
Sales Gas: 0.932 mmsm3/d

Per 01.01.2016 : 
45 active producers, 
6 active injectors.
All numbers for resources and production are gross.

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Valhall by numbers