Operated by Total Exploration & Production Congo, the 30,000-tonne N'Kossa floating production unit (FPU) sits in 170 m of water and is linked to two drilling platforms 3,200 m apart. Alongside production equipment and utilities, the FPU also hosts living quarters for 160 people and installations for water and natural gas injection. Photo from Setec Group subsidiary Diadè;s, Paris.
N'Kossa assay from Total Oil Trading SA's website.
In September 2017, Total Oil Trading SA, the oil and gas trading arm of Total SA, Paris, published a revised crude oil assay dated Aug. 25, 2017, for N'Kossa crude oil, produced offshore the Republic of Congo (Brazzaville) from N'Kossa oil and gas field, located at 3,000 m in water depths of 150-300 m on the Haute Mer permit, about 60 km southwest of Pointe Noire.
Now operated by Total Exploration & Production Congo, N'Kossa field began producing light, sweet crude in 1996 from a floating production unit (FPU) installed in 170 m of water linked to two 11,500-tonne drilling platforms 3,200 m apart (OGJ, Apr. 15, 1996, p. 26). Field installations include two storage and offloading (FSO) tankers: the N´Kossa I FSO with a crude storage capacity of more than 2 million bbl and the 80,000-cu m N'Kossa II FSO for LPG.
Today, N'Kossa is marketed as a blended crude containing production from both N'Kossa and nearby Kitina field. With an average production of about 32,000 b/d, N'Kossa is routed via pipeline to the Total-operated Djeno onshore terminal for loading in 950,000-bbl shipments.
Operator Total holds a 53.5% interest in the N'Kossa development alongside partners Chevron Overseas (Congo) Ltd. 31.5% and Societe Nationale des Pétroles du Congo 15%.
Whole crude
Density at 15° C., kg/m3.: 813.3
Gravity, °API: 42.4
Acidity, mg KOH/g: < 0.05
Sulfur, wt %: 0.041
Mercaptan sulfur, mg/kg: 1
Viscosity at 10° C., cst: 13
Viscosity at 50° C., cst: 3
Pour point, °C.: -3
Total nitrogen, wt %: 0.024
Reid vapor pressure at 37.8° C., kPa: 29
Nickel, mg/kg: 3.6
Vanadium, mg/kg: 0.1
Ethane, wt %: 0.04
Propane, wt %: .034
iso-Butane, wt %: 0.26
n-Butane, wt %: 1.02
Light naphtha, 15-65° C.
Yield on crude, wt %: 5.7
Yield on crude, vol %: 7.1
Density at 15° C., kg/m3.: 644
Research octane no., clear: 70.1
Motor octane no., clear: 69.2
Naphthenes, vol %: 4.9
Aromatics, vol %: 0.4
Light naphtha, 15-80° C.
Yield on crude, wt %: 7.4
Yield on crude, vol %: 9.2
Density at 15° C., kg/m3.: 656
Mercaptan sulfur, mg/kg: 1
Research octane no., clear: 66.2
Motor octane no., clear: 65.3
Naphthenes, vol %: 9.2
Aromatics, vol %: 1.4
Heavy naphtha, 80-150° C.
Yield on crude, wt %: 14.8
Yield on crude, vol %: 16.2
Density at 15° C., kg/m3.: 740
Mercaptan sulfur, mg/kg: 1
Naphthenes, vol %: 33.4
Aromatics, vol %: 8.5
Heavy naphtha, 80-175° C.
Yield on crude, wt %: 20.0
Yield on crude, vol %: 21.7
Density at 15° C., kg/m3.: 748
Mercaptan sulfur, mg/kg: 1
Naphthenes, vol %: 32.9
Aromatics, vol %: 9.6
Heavy naphtha, 100-150° C.
Yield on crude, wt %: 11.6
Yield on crude, vol %: 12.6
Density at 15° C., kg/m3.: 746
Mercaptan sulfur, mg/kg: 1
Naphthenes, vol %: 34.2
Aromatics, vol %: 9.1
Kerosine, 150-230° C.
Yield on crude, wt %: 15.6
Yield on crude, vol %: 16.1
Density at 15° C., kg/m3.: 786
Sulfur, wt %: 0.01
Smoke point, mm: 30
Acidity, mg KOH/g: 0.01
Cetane index 1990 (D-4737): 46.6
Freeze point, °C.: -52
Aromatics, vol %: 14.0
Viscosity at 50° C., cst: 1.0
Flash point, °C.: 55.3
Kerosine, 175-230° C.
Yield on crude, wt %: 10.4
Yield on crude, vol %: 10.6
Density at 15° C., kg/m3.: 794
Sulfur, wt %: 0.01
Smoke point, mm: 29
Acidity, mg KOH/g: 0.01
Cetane index 1990 (D-4737): 48.7
Freeze point, °C.: -46
Aromatics, vol %: 14.8
Viscosity at 50° C., cst: 1.1
Flash point, °C.: 69.4
Kerosine, 150-250° C.
Yield on crude, wt %: 19.6
Yield on crude, vol %: 20.1
Density at 15° C., kg/m3.: 791
Sulfur, wt %: 0.01
Smoke point, mm: 29
Acidity, mg KOH/g: 0.01
Cetane index 1990 (D-4737): 48.5
Freeze point, °C.: -47
Aromatics, vol %: 14.3
Viscosity at 50° C., cst: 1.0
Flash point, °C.: 58.4
Gas oil, 175-400° C.
Yield on crude, wt %: 40.1
Yield on crude, vol %: 39.4
Density at 15° C., kg/m3.: 826
Sulfur, wt %: 0.03
Aniline point, °C.: 78
Cetane index 1990 (D-4737): 56.5
Cloud point, °C.: 2
Cold filter plugging point, °C.: -1
Pour point, °C.: -4
Viscosity at 50° C., cst: 2.4
Viscosity at 100° C., cst: 1.2
UOP K factor: 12.1
Flash point, °C.: 80.6
Gas oil, 230-400° C.
Yield on crude, wt %: 29.8
Yield on crude, vol %: 28.8
Density at 15° C., kg/m3.: 839
Sulfur, wt %: 0.04
Aniline point, °C.: 82
Cetane index 1990 (D-4737): 61.5
Cloud point, °C.: 7
Cold filter plugging point, °C.: 6
Pour point, °C.: 6
Viscosity at 50° C., cst: 3.5
Viscosity at 100° C., cst: 1.6
UOP K factor: 12.1
Flash point, °C.: 105.1
Gas oil, 230-375° C.
Yield on crude, wt %: 26.4
Yield on crude, vol %: 25.6
Density at 15° C., kg/m3.: 836
Sulfur, wt %: 0.03
Aniline point, °C.: 81
Cetane index 1990 (D-4737): 60.9
Cloud point, °C.: 2
Cold filter plugging point, °C.: 1
Pour point, °C.: 1
Viscosity at 50° C., cst: 3.1
Viscosity at 100° C., cst: 1.4
UOP K factor: 12.1
Flash point, °C.: 103.6
Vacuum distillate, 375-550° C.
Yield on crude, wt %: 19.5
Yield on crude, vol %: 17.8
Density at 15° C., kg/m3.: 885
Sulfur, wt %: 0.07
Aniline point, °C.: 104
Total nitrogen, wt %: 0.03
Basic nitrogen, mg/kg: 57
Pour point, °C.: 48
Viscosity at 100° C., cst: 7.1
Viscosity at 150° C., cst: 3.0
UOP K factor: 12.4
Vacuum distillate, 375-565° C.
Yield on crude, wt %: 20.9
Yield on crude, vol %: 19.1
Density at 15° C., kg/m3.: 887
Sulfur, wt %: 0.07
Conradson carbon residue, wt %: 0.1
Aniline point, °C.: 105
Total nitrogen, wt %: 0.03
Basic nitrogen, mg/kg: 66
Pour point, °C.: 49
Viscosity at 100° C., cst: 7.5
Viscosity at 150° C., cst: 3.2
UOP K factor: 12.4
Vacuum distillate, 375-580° C.
Yield on crude, wt %: 22.2
Yield on crude, vol %: 20.3
Density at 15° C., kg/m3.: 888
Sulfur, wt %: 0.07
Conradson carbon residue, wt %: 0.1
Aniline point, °C.: 105
Total nitrogen, wt %: 0.03
Basic nitrogen, mg/kg: 74
Pour point, °C.: 50
Viscosity at 100° C., cst: 8.0
Viscosity at 150° C., cst: 3.3
UOP K factor: 12.4
Vacuum distillate, 400-580° C.
Yield on crude, wt %: 18.8
Yield on crude, vol %: 17.1
Density at 15° C., kg/m3.: 893
Sulfur, wt %: 0.08
Conradson carbon residue, wt %: 0.1
Aniline point, °C.: 107
Nickel, mg/kg: 1
Total nitrogen, wt %: 0.03
Basic nitrogen, mg/kg: 85
Pour point, °C.: 52
Viscosity at 100° C., cst: 9.4
Viscosity at 150° C., cst: 3.8
UOP K factor: 12.4
Residue, > 375° C.
Yield on crude, wt %: 34.2
Yield on crude, vol %: 30.5
Density at 15° C., kg/m3.: 908
Sulfur, wt %: 0.09
Conradson carbon residue, wt %: 3.0
Acidity, mg KOH/g: 0.1
Nickel, mg/kg: 10
Total nitrogen, wt %: 0.02
Pour point, °C.: 39
Viscosity at 100° C., cst: 18
Viscosity at 150° C., cst: 6
Asphaltenes (C7), wt %: 0.4
Residue, > 550° C.
Yield on crude, wt %: 14.7
Yield on crude, vol %: 12.6
Density at 15° C., kg/m3.: 942
Sulfur, wt %: 0.12
Conradson carbon residue, wt %: 6.9
Acidity, mg KOH/g: 0.3
Nickel, mg/kg: 24
Pour point, °C.: 27
Viscosity at 100° C., cst: 115
Viscosity at 150° C., cst: 24
Asphaltenes (C7), wt %: 0.8
Residue, > 565° C.
Yield on crude, wt %: 13.3
Yield on crude, vol %: 11.4
Density at 15° C., kg/m3.: 945
Sulfur, wt %: 0.12
Conradson carbon residue, wt %: 7.6
Acidity, mg KOH/g: 0.3
Nickel, mg/kg: 26
Pour point, °C.: 26
Viscosity at 100° C., cst: 146
Viscosity at 150° C., cst: 28
Penetration, mm/10: 2,200
Asphaltenes (C7), wt %: 0.9
Residue, > 580° C.
Yield on crude, wt %: 11.9
Yield on crude, vol %: 10.2
Density at 15° C., kg/m3.: 949
Sulfur, wt %: 0.12
Conradson carbon residue, wt %: 8.4
Acidity, mg KOH/g: 0.3
Nickel, mg/kg: 29
Vanadium, mg/kg: 1
Pour point, °C.: 25
Viscosity at 100° C., cst: 190
Viscosity at 150° C., cst: 33
Penetration, mm/10: 1,900
Asphaltenes (C7), wt %: 1.0