Page 46: of Offshore Engineer Magazine (Aug/Sep 2014)

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The HPHT challenge

Geology & Geophysics

But, Jackdaw is

High-pressure, high-temperature also an extreme developments are on the ? eld, with 17,250psi increase in the UK North Sea. reservoir pressure and temperatures

Elaine Maslin went to an Oil & at 385°F at its base,

Gas UK breakfast brie? ng in making it the highest pressure ? eld found

Aberdeen to ? nd out more. to date on the UK

Continental Shelf.

orth Sea operators are breaking It is new territory. new ground and investing in BG Group had to

N new technology development qualify new equip- to bring high-pressure, high-temperature ment to carry out a (HPHT) and ultra-HPHT ? elds onstream. 2012 drill stem test

It is an extreme, expensive, and chal- on Jackdaw. Giving lenging game, but one in which many an example of the see the potential for some sizeable new technology that developments in the North Sea. will be required to

The numbers are high. BG Group’s develop the ? eld,

Jackdaw discovery, in central North Sea Samuel said BG has

Blocks 30/2a (BG Group 44.1%), 30/2d been assessing a high

Total E&P UK’s HPHT Elgin Franklin complex. (35%) and 30/3a (30.5%), contains 125- integrity pressure

Image from Total E&P UK. 250MMboe and a wider development protection system taking in other ? elds in the area could (HIPPS), involv- operators, primarily GDF Suez E&P, but ing numerous fast-closing ball valves, unlock 0.5billion boe, BG Group’s manag- to ? nd reserves are in the central North also Maersk, to make it and other projects weighing well over 10-tonne each, on the ing director, Europe E&P, Andy Samuel, Sea, of which 25% is thought to be it work. development’s well head platform. told Oil & Gas UK’s HPHT breakfast brief- HPHT, he says.

Despite the challenges, operators, Jackdaw was discovered in 2005. BG ing in Aberdeen early June. This would “It (HPHT) is a big deal to us, these including BG Group, say there is a “sub- has since run a four-well, £450 million amount to 10% of the UK’s domestic gas are highly technically challenging ? elds stantial yet to ? nd prize” in HPHT. appraisal program, from 2007-2012. consumption needs. we need to develop,” Guys says. But it is

The discovery extends across three also a niche, he adds. “We had to develop

How it is done licenses, with lean gas-condensate in new tools for this.”

Total E&P UK has led the HPHT-way with high permeability Jurassic reservoir, Franklin was discovered in 1986 and its Elgin Franklin HPHT development in similar to Total E&P UK’s Elgin Elgin in 1991. It took 15 years and £20 the central North Sea. It was challenged Franklin development. million of research investment, before with pressures up to 15,500psi and tem- Samuel says BG has been through both could be produced. peratures up to 350°F. concept select on Jackdaw, with a Initial development challenges

It has had a learning curve, due to the three-platform base case concept, included 3-4% carbon dioxide, 30-50ppm 2012 well control incident on Elgin, but “remarkably similar” to a develop- hydrogen sul? de, and a 1100psi, 190°C it is also extending the development. In ment concept chosen by Maersk temperature reservoir. There was also 175 the fourth quarter, it is due to bring on Oil North Sea for its Culzean HPHT g/l formation chlorides. Gas also had to stream two new platforms at the Elgin development, also in the central be delivered to the grid to speci? cation,

Franklin complex—West Franklin and North Sea. which added to the challenges.

Elgin B—part of the development’s life But, costs are crucial on Jackdaw To meet some of these challenges, a extension, from 22 years, as initially and it is taking longer than BG Group large well bore completion (5in, tub- anticipated, to 32 years. had envisaged to make its economics ing) was used to avoid local focal stress

Philippe Guys, managing director, stack up. The ? rm is assessing the on production tubing. A 15,000psi

Total E&P UK, told the Oil & Gas UK potential for Jackdaw to be part of a coiled tubing system was developed for brie? ng that HPHT is a large proportion larger cluster development, taking through tubing perforations, a produc- of Total E&P UK’s operated reserves, in other nearby ? elds and prospects, tion packer was designed and quali? ed totaling 54%. Some 48% of the UK’s yet operated by BG as well as other for Elgin Franklin, and the company had

BG’s Jackdaw discovery. Image from BG Group.

August 2014 | OE oedigital.com 48 048_OE0814_G&G2_HPHT.indd 48 7/22/14 3:13 PM