Page 55: of Offshore Engineer Magazine (Feb/Mar 2014)

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sand types. It has eight main acid stor-

Vessels age tanks, able to hold up to 180,000 US gals concentrate, or up to 414,300 gals at 15% dilution, and 24 liquid additive storage tanks, able to hold fammable fuids, and with remote monitoring and high level alarms.

Proppant delivery is via gravity feeds to two blenders, each with two 12-in.-diam- eter and one 8-in.-diameter horizontal early thirty years after it sand screw. The 12-in. screws are able to brought the frst purpose-built deliver between 250-10,800 lbs/min sand,

N stimulation vessel into the and the 8-in. between 76-2000 lbs/min.

The Blue Orca has fve, 2750 hydraulic

North Sea, Baker Hughes has returned to horsepower (HHP), Gorilla pumps, and the market. two, 650 HHP, pumps. 5½-in. fuid ends

In October last year, the Blue Orca provide a maximum working pressure arrived in Denmark, after a success- (MWP) of 15,000psi (1035bar) at 17.7bbl/ ful journey across the Atlantic from min.

shipbuilder and vessel operator Edison

Chouest Offshore’s yard in Louisiana. Two, aft-mounted, 400ft Cofexip

By mid-November, the vessel had car- hoses, rated to 15,000psi MWP, with ried out its frst acid job for Maersk Olie hydraulic quick disconnects, provide og Gas, offshore Denmark. the connections to platform or rig-based Enclosed tanks positioned above the main deck. Photo courtesy of Elaine Maslin.

The vessel, ordered on the back of a wellheads. non-exclusive contract with Maersk Olie The vessel is compliant for the North Sea over a 4-5 year period, and that Today’s demands include being able og Gas, and built to meet a number of UK, Dutch, Danish and Norwegian the higher level of activity will continue. to perform large-volume, low-rate matrix

Maersk’s requirements, was the eighth in sectors, and could also work in the John Clark, business development acid treatments, high-rate Paccaloni-style

Baker Hughes’ now nine-strong stimula- Mediterranean, offshore West Africa, manager, pressure pumping, Baker matrix acid treatments, acid fracturing tion feet, with further vessels due. and occasionally North Africa and in Hughes, said: “We see the stimulation and high concentration proppant fractur-

It is one of the highest-capacity stimu- the Adriatic, says Tony Martin, director, market in the North Sea increasing year ing. As a minimum, it needs to be able lation vessels globally, designed to treat offshore stimulation, Baker Hughes. after year, with 2015-2016 in particular to pump at 60 bbl/min, with higher rates a large number of stages in wells, which Baker Hughes, whose previous being extremely busy.” preferable for acid fracturing, and must can be up to 12-18 in the North Sea, and North Sea-based stimulation vessel, the The Blue Orca’s design was based on mix all fuids on-the-fy with sea or fresh multiple treatments in one mobilization. Vestfonn, left the region in 2007, believes the past 30 years’ experience, and what water, Martin says. There has also been a

It has 2.5million lbs (1134-tonne) the investment and move back into the Baker Hughes thinks the vessel will need small but increasing demand for treat- proppant storage capacity, in top tanks, basin is worthwhile. to be able to deal with in the next 30 ments in high-pressure, high-temperature and lower sand silos, which are divided Martin says the company expects an years, including reservoir pressures and formations, he says. into four compartments, for multiple increase in stimulation activity in the temperatures. A key consideration was redundancy,

Baker Hughes, Schlumberger, and type at the time, and remain so, Martin says, It has 180,000-gallon raw acid storage

The North Sea

Halliburton, soon stepped in to fll the in paper SPE 168243. The requirements of capacity and more than 1.2 million pound- stimulation vessel feet gap. Baker Hughes brought the 1983-built the stimulation treatments far exceeded any- mass (lbm) (544,310.9 kg) for proppant.

The stimulation market in the North 82.3m-long on to the market in thing required in other parts of the world. The , remains in the North

Vestfonn Big Orange VIII

Sea began in earnest in the 1960s, with 1986. These requirements entailed mobilizing Sea. It has 4800- and 10,000-psi (at 58- and temporarily-placed, skid-mounted, limited In 1984, Schlumberger introduced to the world’s largest capacity to store and 70 barrels per minute (bpm) pumps, sup- scale, equipment on platforms. the market the 74m-long , blend raw hydrochloric acid, and the ability to ported by 12,000-hydraulic pumping capac-

Big Orange XVIII

According to 1984 SPE paper 12993-MS, on a long term contract from owner Tracer store and blend unprecedented quantities of ity. Schlumberger ofers pumping pressures stimulation operations from a vessel were Ofshore ANS, and managed by Wilhelmsen proppant. of up to 15,000-psi on request. frst carried out in 1980, in the southern Ship Management. The , which left the North Sea Big has 180,000-gallon raw

Vestfonn Orange VIII

North Sea from a small Arabian Gulf vessel. in 2007, and has been working ofshore acid storage capacity and 15,400cu ft total

The following year, Halliburton contracted

This led to the conversion of two large India since, has 10,000- and 15,000-psi proppant storage capacity. the 88m-long , owned by DOF Skandi Fjord (at the time) North Sea supply vessels into (68.9- and 103.4-MPa) pumps, supported by The is understood to have

Subsea and managed by DOF Management AS.

Skandi Fjord dedicated stimulation vessels, operating in The three vessels were the largest of their 13,400-hydraulic pumping capacity. just been decommissioned. It also had the northern and southern sectors.

The .Big Orange VIII

Their capability was quickly found want-

Skandi Fjord Island Patriot . The The .

Photo courtesy of Elaine Maslin.

ing, specifcally around pumping, batch- mixing and proppant-carrying capacity.

Maximum pumping power on both vessels was 4000-5000 horsepower (hp) and qual- ity control and job monitoring were also limited. oedigital.com February 2014 | OE 57 056_OE0214_vessels1.indd 57 1/20/14 9:40 PM