GUIDE TO WORLD CRUDES: Five deepwater Angola fields comprise Plutonio blend

Plutonio is a low-sulfur, medium-gravity crude oil from Angola's deepwater Block 18. Greater Plutonio consists of five oil fields from water depths of around 1,300 m: Plutonio, Galio, Paladio, Cromio, and Cobalto, all of which lie within 20 km of each other and whose production forms the Plutonio crude blend. Samples have shown these five fields to be very similar in quality, says BP PLC.

Production began in September 2007 (OGJ, Oct. 8, 2007, p. 8) and quickly reached more than 200,000 b/d. The assay given here is from a sample dated Mar. 18, 2008.

According to BP, the Angolan deep water has seen considerable exploration success in Blocks 15, 17, and 18, where BP is operator. BP also operates the ultradeep water Block 31, which by yearend 2009 had yielded 13 exploration successes.

Greater Plutonio is being developed and operated by BP with a 50% equity interest. The remainder is owned by Sonangol Sinopec International Ltd, the joint venture between China Petroleum & Chemical Corp. (Sinopec) and Sonangol, Angola's national oil company.

Oil produced on Plutonio is exported via a dedicated floating production, storage, and offloading (FPSO) vessel, loading through its own remote offloading buoy close to the production platform. The FPSO (photo) has storage capacity of 1.74 million bbl, processing capacity of 240,000 b/d of oil, and gas handling of as much as 400 MMscfd (OGJ Online, Oct. 2, 2007). The vessel has a treated-water injection rate of 450,000 b/d.

According to BP, crude export parcel sizes are 1 million bbl. The buoy can accept either SuezMax or VLCC (very large crude carrier) vessels for "combi-cargoes," both as first or second cargo loads. With peak production in excess of 200,000 b/d, a cargo is available about every 5 days.

BP made its first discovery on the block in 1999-2001 in 1,200-1,450 m of water. The area's final development plan called for 43 wells—20 producers, 20 water injectors, and 3 gas injectors.

The subsea system includes the longest single riser tower of its kind in the world, BP said in 2007. At 1,258 m, it connects the FPSO to a network of subsea flow line and control systems that include 150 km of flow lines, nine manifolds, and 110 km of instrument and control umbilicals.

Whole crude*

API gravity at 60/60° F.: 33.2

Density at 15° C., kg/l.: 0.8585

Total sulfur, wt %: 0.36

Mercaptan sulfur, wt %: 0.0001

H2S, ppm (wt): <5*

Vis. at 20° C., cst: 14.5

Vis. at 30° C., cst: 10.5

Vis. at 40° C., cst: 7.95

Vis. at 50° C., cst: 6.18

Vis. at 60° C., cst: 4.93

Vis. at 100° C., cst: 2.4

Pour point, °C.: 6

Wax, wt %: 10.0

Total nitrogen, ppm (wt): 2,020

Basic nitrogen, ppm (wt): 707

Acidity, mg KOH/g: 0.151

Carbon residue, wt %: 3.52

Asphaltenes, wt %: 0.328

Vanadium, ppm (wt): 5.9

Nickel, ppm (wt): 20.9

Iron, ppm (wt): 3.2

Mercury, ppb (wt): <1

C₂ & lighter, wt %: 0.02

C₃, wt %: 0.31

i-C₄, wt %: 0.23

n-C₄, wt %: 0.85

i-C₅, wt %: 0.72

n-C₅, wt %: 0.91

C₅ to 95° C.

Yield on crude, wt %: 6.37

Yield on crude, vol %: 7.94

Density at 15° C., kg/l.: 0.6870

Mercaptan sulfur, wt %: 0.0001

Total nitrogen, ppm (wt): 0.01

Acidity, mg KOH/g: 0.0722

Research octane no.: 67.8

Paraffins, wt %: 66.6

n-Paraffins, wt %: 26.6

Naphthenes, wt %: 32.1

Aromatics, vol %: 1.4

95-175° C.

Yield on crude, wt %: 11.932

Yield on crude, vol %: 13.42

Density at 15° C., kg/l.: 0.7603

Sulfur, wt %: 0.006

Mercaptan sulfur, ppm: 0.0002

Total nitrogen, ppm (wt): 0.69

Acidity, mg KOH/g: 0.0787

Research octane no.: 51.7

Paraffins, wt %: 45.1

n-Paraffins, wt %: 19.8

Naphthenes, wt %: 44.1

Aromatics, vol %: 10.8

C₅ to 149° C.

Yield on crude, wt %: 14.349

Yield on crude, vol %: 17.01

Density at 15° C., kg/l.: 0.7214

Sulfur, wt %: 0.001

Mercaptan sulfur, wt %: 0.0001

Total nitrogen, ppm (wt): 0.11

Acidity, mg KOH/g: 0.0757

Research octane no.: 61.8

Paraffins, wt %: 55.1

n-Paraffins, wt %: 23.1

Naphthenes, wt %: 55.1

Aromatics, vol %: 5.5

149-232° C.

Yield on crude, wt %: 12.377

Yield on crude, vol %: 13.29

Density at 15° C., kg/l.: 0.7964

Sulfur, wt %: 0.029

Mercaptan sulfur, wt %: 0.0002

Vis. at 40° C., cst: 1.14

Vis. at 60° C., cst: 0.89

Total nitrogen, ppm (wt): 5.01

Acidity, mg KOH/g: 0.0858

Smoke point, mm: 26

Freezing point, °C.: –59

Cetane index (ASTM D4737-90): 42.7

Refractive index at 70 °C.: 1.4191

Naphthalenes, vol %: 0.8

Aromatics, vol %: 14.69

232-342° C.

Yield on crude, wt %: 19.131

Yield on crude, vol %: 19.48

Density at 15° C., kg/l.: 0.8401

Sulfur, wt %: 0.158

Mercaptan sulfur, wt %: 0.0001

Vis. at 50° C., cst: 2.81

Vis. at 100° C., cst: 1.32

Cloud point, °C.: –12

Pour point, °C.: –13

Wax, wt %: 6.1

Total nitrogen, ppm (wt): 72.0

Basic nitrogen, ppm (wt): 28

Acidity, mg KOH/g: 0.131

Smoke point, mm: 20

Freezing point, °C.: –9

Cetane index (ASTM D4737-90): 56.9

Refractive index at 70 °C.: 1.4465

Naphthalenes, vol %: 6.5

Aromatics, vol %: 20.45

Aromatics, wt %: 23.2

342-369° C.

Yield on crude, wt %: 4.344

Yield on crude, vol %: 4.26

Density at 15° C., kg/l.: 0.8729

Sulfur, wt %: 0.358

Vis. at 50° C., cst: 7.16

Vis. at 100° C., cst: 2.52

Cloud point, °C.: 15.0

Pour point, °C.: 15.0

Wax, wt %: 20.6

Total nitrogen, ppm (wt): 423

Basic nitrogen, ppm (wt): 122

Acidity, mg KOH/g: 0.16

Aniline point, °C.: 81.4

Cetane index (ASTM D4737-90): 63.9

Refractive index at 70 °C.: 1.4637

369-509° C.

Yield on crude, wt %: 21.895

Yield on crude, vol %: 20.8

Density at 15° C., kg/l.: 0.9005

Sulfur, wt %: 0.430

Vis. at 60° C., cst: 19.7

Vis. at 100° C., cst: 6.37

Pour point, °C.: 38.0

Wax, wt %: 20.0

Total nitrogen, ppm (wt): 1,340

Basic nitrogen, wt %: 428

Acidity, mg KOH/g: 0.129

Carbon residue, wt %: 0.0093

Asphaltenes, wt %: 0.0021

Aniline point, °C.: 91.0

Refractive index at 70 °C.: 1.4801

509-550° C.

Yield on crude, wt %: 5.229

Yield on crude, vol %: 4.82

Density at 15° C., kg/l.: 0.9279

Sulfur, wt %: 0.616

Vis. at 60° C., cst: 105.0

Vis. at 100° C., cst: 20.6

Wax, wt %: 20.0

Total nitrogen, ppm (wt): 2,950

Basic nitrogen, ppm (wt): 962

Acidity, mg KOH/g: 0.154

Carbon residue, wt %: 0.803

Asphaltenes, wt %: 0.0366

Aniline point, °C.: 98.5

Refractive index at 70 °C.: 1.4988

550-585° C.

Yield on crude, wt %: 3.427

Yield on crude, vol %: 3.11

Density at 15° C., kg/l.: 0.9413

Sulfur, wt %: 0.721

Vis. at 60° C., cst: 240.0

Vis. at 100° C., cst: 36.8

Wax, wt %: 20.1

Total nitrogen, ppm (wt): 3,830

Basic nitrogen, ppm (wt): 1,300

Acidity, mg KOH/g: 0.143

Carbon residue, wt %: 2.65

Asphaltenes, wt %: 0.12

Aniline point, °C.: 100.5

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