ExxonMobil publishes updated assay for Equatoguinean Zafiro Blend

Converted from a former 307,000-dwt tanker and purchased from SBM Offshore NV, Rotterdam, in 2005, the ExxonMobil Corp.-operated Serpentina floating, production, storage, and offloading vessel, began producing oil from the Zafiro Southern Expansion Area in July 2003 from 475 m of water on Block B in the Zafiro field, about 40 miles off Equatorial Guinea in the Gulf of Guinea, adjacent to the international border with Nigeria. Photo from SBM Offshore.

First produced in 1996 from the 547,000-acre Block B off Bioko Island in the Gulf of Guinea from subsea installations tied back via flexible risers to the Zafiro Producer floating production, storage, and offloading (FPSO) system (OGJ, Sept. 2, 1996, p. 38), and later the Mobil Equatorial Guinea-operated Jade platform (OGJ Online, June 26, 2000), Zafiro crude output was merged with production from 1 Topacio well, a 3-mile, south-extension well of Zafiro field (OGJ, Apr. 1, 1996, p. 26).

With production averaging about 120,000 b/d, the "new" Zafiro Blend consists of hydrocarbons from Equatorial Guinea's Zafiro, Jade, Opalo, Sausage, and Serpentina reservoirs, transported via pipeline to Serpentina FPSO for loading, the operator said.

Before reaching a peak of more than 300,000 b/d in 2004, production from Zafiro field in 2005 averaged more than 260,000 b/d of gross oil through the Serpentina FPSO, the Jade platform, and the Zafiro Producer unit (OGJ Online, Jan. 25, 2007), according to Equatorial Guinea's Ministry of Mines, Industry, and Energy.

GE Petrol has estimated ultimate recovery from Zafiro field of 1.199 billion bbl.

Whole crude

Yield on crude, vol %: 100.00
Gravity, °API: 30.2012
Specific gravity, 60° F.: 0.87507
Carbon, wt %: 86.5566
Hydrogen, wt %: 12.9709
Pour point, °F.: -59.8
Total acid no., mg KOH/g: 0.74
Sulfur, wt %: 0.25101
Viscosity at 20° C., cst: 12.4149
Viscosity at 40° C., cst: 6.58626
Viscosity at 50° C., cst: 5.0852
Viscosity at 100° C., cst: 2.01008
Viscosity at 150° C., cst: 1.12202
Mercaptan sulfur, ppm: 0.6
Nitrogen, ppm: 2,324.15
Conradson carbon residue, wt %: 2.91222
n-Heptane insolubles, wt %: 0.11104
Nickel, ppm: 14.0633
Vanadium, ppm: 2.31732
Calcium, ppm: 0.5
Reid vapor pressure, psi: 5.5
Salt content, lb/'000 bbl: 3.6
Paraffins, vol %: 23.9211
Naphthenes, vol %: 41.1054
Aromatics, vol %: 34.9735
Distillation type, D-: 86
ASTM distillation, °F.-IBP: 57.9803
5 vol % recovered: 190.691
10 vol % recovered: 248.929
20 vol % recovered: 331.387
30 vol % recovered: 410.153
40 vol % recovered: 486.487
50 vol % recovered: 561.205
60 vol % recovered: 645.144
70 vol % recovered: 739.906
80 vol % recovered: 860.597
90 vol % recovered: 1,015.74
95 vol % recovered: 1,063.21
End point, °F.: 1,145.44
Freeze point, °F.: 101.012
Smoke point, mm: 14.0904
Naphthalenes (D-1840), vol %: 6.67267
Cetane index 1990 (D-4737): 27.8026
Cloud point, °F.: 92.3041
Aniline point, °F.: 151.737

Butanes and lighter

Yield on crude, vol %: 1.42
Gravity, °API: 123.10
Specific gravity, 60° F.: 0.56
Carbon, wt %: 82.43
Hydrogen, wt %: 17.57
Pour point, °F.: -218.15
Viscosity at 20° C., cst: 0.43
Viscosity at 40° C., cst: 0.37
Viscosity at 50° C., cst: 0.34
Viscosity at 100° C., cst: 0.26
Viscosity at 150° C., cst: 0.20
Mercaptan sulfur, ppm: 0.78
Reid vapor pressure, psi: 111.75
Paraffins, vol %: 100.00
Distillation type, D-: 86
ASTM distillation, °F.-IBP: -113.97
5 vol % recovered: -94.39
10 vol % recovered: -76.04
20 vol % recovered: -27.80
30 vol % recovered: 19.53
40 vol % recovered: 24.60
50 vol % recovered: 34.23
60 vol % recovered: 37.07
70 vol % recovered: 39.92
80 vol % recovered: 42.63
90 vol % recovered: 45.35
95 vol % recovered: 49.12
End point, °F.: 60.70
Freeze point, °F.: -206.45
Smoke point, mm: 32.38
Cetane index 1990 (D-4737): 159.16
Cloud point, °F.: -213.96
Aniline point, °F.: 186.13

Light naphtha

Yield on crude, vol %: 3.99
Gravity, °API: 81.99
Specific gravity, 60° F.: 0.66
Carbon, wt %: 83.95
Hydrogen, wt %: 16.05
Pour point, °F.: -180.76
Viscosity at 20° C., cst: 0.57
Viscosity at 40° C., cst: 0.47
Viscosity at 50° C., cst: 0.43
Viscosity at 100° C., cst: 0.31
Viscosity at 150° C., cst: 0.24
Mercaptan sulfur, ppm: 9.35
Reid vapor pressure, psi: 13.87
Paraffins, vol %: 79.35
Naphthenes, vol %: 20.65
Distillation type, D-: 86
ASTM distillation, °F.-IBP: 99.15
5 vol % recovered: 100.85
10 vol % recovered: 101.46
20 vol % recovered: 104.33
30 vol % recovered: 111.99
40 vol % recovered: 117.17
50 vol % recovered: 127.89
60 vol % recovered: 133.37
70 vol % recovered: 138.26
80 vol % recovered: 142.42
90 vol % recovered: 146.29
95 vol % recovered: 152.80
End point, °F.: 158.66
Freeze point, °F.: -169.68
Smoke point, mm: 29.13
Cetane index 1990 (D-4737): 48.88
Cloud point, °F.: -176.84
Aniline point, °F.: 152.64

Heavy naphtha

Yield on crude, vol %: 16.07
Gravity, °API: 53.78
Specific gravity, 60° F.: 0.76
Carbon, wt %: 85.71
Hydrogen, wt %: 14.29
Pour point, °F.: -132.18
Total acid no., mg KOH/g: 0.03
Sulfur, wt %: 0.02
Viscosity at 20° C., cst: 0.91
Viscosity at 40° C., cst: 0.72
Viscosity at 50° C., cst: 0.65
Viscosity at 100° C., cst: 0.42
Viscosity at 150° C., cst: 0.31
Mercaptan sulfur, ppm: 43.23
Nitrogen, ppm: 1.21
Reid vapor pressure, psi: 1.08
Paraffins, vol %: 31.31
Naphthenes, vol %: 59.96
Aromatics, vol %: 8.73
Distillation type, D-: 86
ASTM distillation, °F.-IBP: 211.68
5 vol % recovered: 215.58
10 vol % recovered: 218.44
20 vol % recovered: 226.96
30 vol % recovered: 234.59
40 vol % recovered: 244.16
50 vol % recovered: 253.37
60 vol % recovered: 263.30
70 vol % recovered: 273.13
80 vol % recovered: 283.49
90 vol % recovered: 293.81
95 vol % recovered: 302.71
End point, °F.: 313.19
Freeze point, °F.: -120.05
Smoke point, mm: 24.45
Cetane index 1990 (D-4737): 27.63
Cloud point, °F.: -127.91
Aniline point, °F.: 119.83

Kerosine

Yield on crude, vol %: 16.98
Gravity, °API: 38.91
Specific gravity, 60° F.: 0.83
Carbon, wt %: 86.30
Hydrogen, wt %: 13.63
Pour point, °F.: -78.56
Total acid no., mg KOH/g: 0.15
Sulfur, wt %: 0.06
Viscosity at 20° C., cst: 2.02
Viscosity at 40° C., cst: 1.45
Viscosity at 50° C., cst: 1.26
Viscosity at 100° C., cst: 0.72
Viscosity at 150° C., cst: 0.47
Mercaptan sulfur, ppm: 12.21
Nitrogen, ppm: 15.42
Reid vapor pressure, psi: 0.04
Paraffins, vol %: 26.34
Naphthenes, vol %: 55.69
Aromatics, vol %: 17.97
Distillation type, D-: 86
ASTM distillation, °F.-IBP: 365.71
5 vol % recovered: 367.54
10 vol % recovered: 369.24
20 vol % recovered: 375.87
30 vol % recovered: 382.45
40 vol % recovered: 391.47
50 vol % recovered: 400.35
60 vol % recovered: 410.03
70 vol % recovered: 419.56
80 vol % recovered: 429.46
90 vol % recovered: 439.20
95 vol % recovered: 447.86
End point, °F.: 457.88
Freeze point, °F.: -63.22
Smoke point, mm: 18.91
Naphthalenes (D-1840), vol %: 1.58
Cetane index 1990 (D-4737): 35.05
Cloud point, °F.: -75.22
Aniline point, °F.: 130.46

Diesel

Yield on crude, vol %: 19.91
Gravity, °API: 30.95
Specific gravity, 60° F.: 0.87
Carbon, wt %: 86.83
Hydrogen, wt %: 12.94
Pour point, °F.: -5.13
Total acid no., mg KOH/g: 0.79
Sulfur, wt %: 0.19
Viscosity at 20° C., cst: 8.57
Viscosity at 40° C., cst: 4.76
Viscosity at 50° C., cst: 3.75
Viscosity at 100° C., cst: 1.58
Viscosity at 150° C., cst: 0.91
Mercaptan sulfur, ppm: 2.06
Nitrogen, ppm: 163.15
Paraffins, vol %: 23.93
Naphthenes, vol %: 49.62
Aromatics, vol %: 26.45
Distillation type, D-: 86
ASTM distillation, °F.-IBP: 509.17
5 vol % recovered: 512.30
10 vol % recovered: 514.28
20 vol % recovered: 521.40
30 vol % recovered: 528.54
40 vol % recovered: 538.45
50 vol % recovered: 548.46
60 vol % recovered: 559.75
70 vol % recovered: 571.20
80 vol % recovered: 583.86
90 vol % recovered: 596.81
95 vol % recovered: 606.74
End point, °F.: 618.63
Freeze point, °F.: 9.36
Smoke point, mm: 13.83
Naphthalenes (D-1840), vol %: 9.40
Cetane index 1990 (D-4737): 46.27
Cloud point, °F.: -1.40
Aniline point, °F.: 149.70

Vacuum gas oil

Yield on crude, vol %: 26.64
Gravity, °API: 19.82
Specific gravity, 60° F.: 0.94
Carbon, wt %: 87.20
Hydrogen, wt %: 12.18
Pour point, °F.: 86.90
Total acid no., mg KOH/g: 1.38
Sulfur, wt %: 0.34
Viscosity at 20° C., cst: 648.15
Viscosity at 40° C., cst: 138.48
Viscosity at 50° C., cst: 75.79
Viscosity at 100° C., cst: 10.32
Viscosity at 150° C., cst: 3.48
Mercaptan sulfur, ppm: 0.26
Nitrogen, ppm: 1,997.23
Conradson carbon residue, wt %: 0.11
Paraffins, vol %: 14.63
Naphthenes, vol %: 36.88
Aromatics, vol %: 48.50
Distillation type, D-: 1,160
ASTM distillation, °F.-IBP: 678.27
5 vol % recovered: 686.44
10 vol % recovered: 693.09
20 vol % recovered: 718.10
30 vol % recovered: 744.20
40 vol % recovered: 770.99
50 vol % recovered: 798.03
60 vol % recovered: 830.71
70 vol % recovered: 866.15
80 vol % recovered: 905.25
90 vol % recovered: 949.30
95 vol % recovered: 973.69
End point, °F.: 999.08
Freeze point, °F.: 99.21
Smoke point, mm: 7.52
Naphthalenes (D-1840), vol %: 11.14
Cetane index 1990 (D-4737): 44.98
Cloud point, °F.: 91.67
Aniline point, °F.: 166.82

Vacuum residue

Yield on crude, vol %: 11.99
Gravity, °API: 6.31
Specific gravity, 60° F.: 1.03
Carbon, wt %: 86.71
Hydrogen, wt %: 11.73
Pour point, °F.: 134.39
Total acid no., mg KOH/g: 0.82
Sulfur, wt %: 0.66
Viscosity at 20° C., cst: 31,474,105,222.23
Viscosity at 40° C., cst: 145,161,812.14
Viscosity at 50° C., cst: 17,367,215.40
Viscosity at 100° C., cst: 15,221.22
Viscosity at 150° C., cst: 387.56
Mercaptan sulfur, ppm: 0.01
Nitrogen, ppm: 11,716.21
Conradson carbon residue, wt %: 20.37
n-Heptane insolubles, wt %: 0.79
Nickel, ppm: 99.62
Vanadium, ppm: 16.41
Paraffins, vol %: 0.83
Naphthenes, vol %: 6.80
Aromatics, vol %: 92.37
Distillation type, D-: 1,160
ASTM distillation, °F.-IBP: 1,025.51
5 vol % recovered: 1,032.72
10 vol % recovered: 1,038.24
20 vol % recovered: 1,059.39
30 vol % recovered: 1,082.47
40 vol % recovered: 1,108.39
50 vol % recovered: 1,137.65
60 vol % recovered: 1,175.72
70 vol % recovered: 1,220.85
80 vol % recovered: 1,277.12
90 vol % recovered: 1,354.17
95 vol % recovered: 1,408.66
End point, °F.: 1,491.98
Freeze point, °F.: 150.10
Smoke point, mm: 2.85
Naphthalenes (D-1840), vol %: 10.28
Cetane index 1990 (D-4737): 21.05
Cloud point, °F.: 142.81
Aniline point, °F.: 179.97