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Field of View

The Culzean wellhead jacket under fabrication.

Images from Maersk Oil.

uHPHT allowance hub means that the area shouldn’t just

Taming

Culzean is the frst development to see new developments, but also an beneft from a new ultra high-pressure, increase in exploration and appraisal. high-temperature (uHPHT) cluster tax “With the introduction of a tax break allowance on the UK Continental Shelf. for uHPHT felds of the UK, along with

The allowance was designed to encour- the simultaneous advances in technol-

Culzean age the development of uHPHT felds ogy, now is a better time than ever for

Mastering high-pressure, high-temperature reservoirs has been that are economic, but not commercially operators to develop HPHT assets and viable because of the current 62% tax a UK North Sea challenge for more than a decade. Maersk Oil to continue exploration and appraisal in imposed on normal felds.

nearby areas,” she says. “Maybe, since is taking lessons learned by others and applying them to the “The project may signal a turning point the introduction of the tax allowance,

Culzean feld.

for the crisis facing the UK North Sea the UK will see more and more uHPHT where projects continue to be delayed or developments ofshore, and that could put on hold,” says Rebecca Edgill, IHS. be what sets the area apart from other By Elaine Maslin a utilities and living quarters platform, “And the allowance including a cluster regions.” ith few major upstream construction on which is now under way.

projects reaching fnal The reservoir, in about 90m water

W investment decision in the depth, is approximately 4300m below jackup rig. This was Maersk Oil’s frst UK current climate, Maersk Oil’s Culzean is sea level, reaching some 348°F or 176°C, HPHT exploration well. The discovery one of the UK North Sea’s bright sparks. and around 13,500psi, some 240km from well found gas and condensate within the

Approved in August 2015, the US$4.7 Aberdeen. It is not far from the Elgin, target reservoirs of Triassic and Jurassic billion, 270 MMboe plus project is Franklin and Shearwater HPHT felds, age. Further appraisal was then carried out not just a signifcant project, signaling operated by Total and Shell, respectively, during 2009-12, with three, 5km-long wells.

contracts and jobs, it is also complex, in the East Central Graben area of the It was always likely to be a HPHT with high-pressure and high-temperature central North Sea. reservoir at that depth, says Martin (HPHT) reservoirs, offering challenges Maersk expects frst gas in 2019, and Urquhart, project director. “The pres- around materials selection, drilling, well plateau production to be in the range sure is equivalent to being under 9km of completion design, and feld drainage of 300-450 MMscf/d and 25,000 b/d water and the temperature to what you philosophy, to name but a few. condensate. roast your Sunday dinner at,” he says.

Maersk Oil’s development plan for “Because of the reservoirs we were target-

Beginnings

Culzean, which could provide about 5% ing, at the depths we were targeting, you of the UK’s total gas consumption by Although the area was tested in 1986, know it’s likely going to be HPHT.” 2020-21, is a new three-platform instal- Culzean itself was discovered in late 2008, The appraisal campaign had to be eff- lation, consisting a 12-slot wellhead with discovery well (22/25a-9z), in Block cient, due to the high costs involved in platform, central processing facility and 22/25, using the Ensco 101 heavy duty drilling such deep, high-temperature and

December 2015 | OE oedigital.com 18 018_OE1215_field of View.indd 18 11/21/15 12:32 AM