BP Oil International Ltd., a subsidiary of BP PLC, published an assay dated July 18, 2019, for Culzean light sweet crude oil, produced from high-pressure, high-temperature (HPHT) Culzean natural gas and condensate field in the East Central Graben of UK North Sea Block 22/25a (License P111), about 230 km east of Aberdeen in 88 m of water.
Discovered in December 2008 in the Culzean sandstone reservoir about 4,300 m below sea level, with 13,500 psi and 175° C., Total SA-operated Culzean field—which contains gas and condensate within Triassic and Jurassic reservoirs—began production in June 2019 from six wells and three bridge-linked platforms in water depths of about 100 m linked to the Ailsa floating storage and offloading (FSO) vessel (OGJ Online, June 11, 2019; May 11, 2018; Jan. 30, 2009).
Containing virtually zero sulfur and other contaminants such as nitrogen, nickel, and vanadium, Culzean crude is rich in naphtha and middle distillates, with relatively small vacuum gas oil and residue levels, making it a useful crude for refineries seeking to blend with heavier crude grades.
Sold on a delivered basis in standard parcel sizes of 250,000 bbl (±10%), stabilized Culzean crude is exported from the Ailsa FSO—with a storage capacity of 430,000 bbl—onto dedicated shuttle tankers for delivery to northwestern European markets, to which the development’s proximity enables shipment to many refiners in less than 2 days. Produced gas is exported via the Central Area Transmission System (CATS) pipeline, coming onshore at Teesside in northeast England.
Containing resources estimated between 250-300 million boe, Culzean field has a plateau production of 100,000 boe/d of condensate and gas, which will account for about 5% of the UK’s gas consumption.
Alongside BP (32%), Culzean field partners include operator Total (49.99%) and JX Nippon Exploration & Production (UK) Ltd. (18.01%).
Whole crude
API gravity at 60/60° F.: 49.0
Density at 15° C., kg/l.: 0.7836
Total sulfur, wt %: 0.010
Mercaptan sulfur, ppm (wt): 2
Total nitrogen, ppm (wt): 2.1
Basic nitrogen, ppm (wt): 0.634
Acidity, mg KOH/g: 0.030
Vis. at 20° C., cst: 1.902
Vis. at 30° C., cst: 1.521
Vis. at 40° C., cst: 1.249
Vis. at 50° C., cst: 1.047
Pour point, °C.: –6
Wax, wt %: 12.0
Vanadium, ppm (wt): < 2
Nickel, ppm (wt): < 2
Iron, ppm (wt): < 1
Ethane, wt %: 0.02
Propane, wt %: 0.44
Isobutane, wt %: 0.50
n-Butane, wt %: 1.26
Isopentane, wt %: 1.34
n-Pentane, wt %: 1.62
Cyclopentane, wt %: 0.11
C6 paraffins, wt %: 4.02
C6 naphthenes, wt %: 2.06
Benzene, wt %: 1.70
Light naphtha, C5 to 95° C.
Yield on crude, wt %: 13.55
Yield on crude, vol %: 15.10
Density at 15° C., kg/l.: 0.7004
Total sulfur, wt %: < 0.001
Mercaptan sulfur, ppm (wt): 2
Total nitrogen, ppm (wt): 0.3
Acidity, mg KOH/g: 0.004
Paraffins, wt %: 66.17
Naphthenes, wt %: 21.27
Aromatics, wt %: 12.56
n-Paraffins, wt %: 26.49
Research octane no.: 72
Heavy naphtha, 95-149° C.
Yield on crude, wt %: 23.75
Yield on crude, vol %: 23.85
Density at 15° C., kg/l.: 0.7793
Total sulfur, wt %: < 0.001
Mercaptan sulfur, ppm (wt): 2
Total nitrogen, ppm (wt): 1.0
Acidity, mg KOH/g: 0.010
Paraffins, wt %: 35.64
Naphthenes, wt %: 27.76
Aromatics, wt %: 36.60
n-Paraffins, wt %: 19.95
Research octane no.: 65
149-175° C.
Yield on crude, wt %: 8.65
Yield on crude, vol %: 8.70
Density at 15° C., kg/l.: 0.7788
Total sulfur, wt %: < 0.001
Mercaptan sulfur, ppm (wt): 2
Total nitrogen, ppm (wt): 1.0
Acidity, mg KOH/g: 0.015
Paraffins, wt %: 56.57
Naphthenes, wt %: 14.44
Aromatics, wt %: 28.99
n-Paraffins, wt %: 35.38
Kerosine, 175-232° C.
Yield on crude, wt %: 13.00
Yield on crude, vol %: 12.75
Density at 15° C., kg/l.: 0.7965
Total sulfur, wt %: < 0.001
Mercaptan sulfur, ppm (wt): 2
Total nitrogen, ppm (wt): 0.5
Acidity, mg KOH/g: 0.017
Vis. at 40° C., cst: 1.272
Vis. at 60° C., cst: 0.9896
Smoke point, mm: 23.9
Aromatics, vol %: 21.6
Naphthalenes, wt %: 2.93
Freezing point, °C.: –47.5
Cetane index (ASTM D4737-90): 47.1
Refractive index at 70° C.: 1.4285
Light gas oil, 232-342° C.
Yield on crude, wt %: 21.55
Yield on crude, vol %: 20.40
Density at 15° C., kg/l.: 0.8283
Total sulfur, wt %: 0.018
Mercaptan sulfur, ppm (wt): 2
Total nitrogen, ppm (wt): 0.8
Acidity, mg KOH/g: 0.020
Vis. at 50° C., cst: 2.570
Vis. at 100° C., cst: 1.265
Aromatics, wt %: 21.20
Smoke point, mm: 20.8
Aromatics, vol %: 17.8
Naphthalenes, wt %: 9.32
Pour point, °C.: –6
Cloud point, °C.: –4
Freezing point, °C.: –4.0
Cetane index (ASTM D4737-90): 61.1
Refractive index at 70° C.: 1.4439
Wax, wt %: 13.2
Heavy gas oil, 342-369° C.
Yield on crude, wt %: 3.95
Yield on crude, vol %: 3.70
Density at 15° C., kg/l.: 0.8336
Total sulfur, wt %: 0.052
Total nitrogen, ppm (wt): 4.9
Basic nitrogen, ppm (wt): 1.000
Acidity, mg KOH/g: 0.030
Vis. at 50° C., cst: 5.770
Vis. at 100° C., cst: 2.439
Pour point, °C.: 27
Cloud point, °C.: 27
Cetane index (ASTM D4737-90): 86.1
Refractive index at 70° C.: 1.4478
Aniline point, °C.: 97.9
Wax, wt %: 44.7
Light vacuum gas oil, 369-509° C.
Yield on crude, wt %: 11.70
Yield on crude, vol %: 10.95
Density at 15° C., kg/l.: 0.8395
Total sulfur, wt %: 0.023
Total nitrogen, ppm (wt): 7.6
Basic nitrogen, ppm (wt): 3.000
Acidity, mg KOH/g: 0.050
Vis. at 60° C., cst: 9.9880
Vis. at 100° C., cst: 4.283
Pour point, °C.: 48
Refractive index at 70° C.: 1.4464
Aniline point, °C.: 110.2
Wax, wt %: 57.0
Carbon residue, wt %: 0.01
Heavy vacuum gas oil, 509-550° C.
Yield on crude, wt %: 0.80
Yield on crude, vol %: 0.70
Density at 15° C., kg/l.: 0.8569
Total sulfur, wt %: 0.039
Total nitrogen, ppm (wt): 21.0
Basic nitrogen, ppm (wt): 7.000
Acidity, mg KOH/g: 0.090
Vis. at 60° C., cst: 62.9200
Vis. at 100° C., cst: 12.550
Refractive index at 70° C.: 1.4429
Aniline point, °C.: 121.4
Wax, wt %: 42.0
Carbon residue, wt %: 0.31
550-585° C.
Yield on crude, wt %: 0.45
Yield on crude, vol %: 0.40
Density at 15° C., kg/l.: 0.8704
Total sulfur, wt %: 0.045
Total nitrogen, ppm (wt): 29.0
Basic nitrogen, ppm (wt): 10.000
Acidity, mg KOH/g: 0.120
Vis. at 60° C., cst: 196.3000
Vis. at 100° C., cst: 21.5000
Aniline point, °C.: 123.5
Wax, wt %: 28.7
Carbon residue, wt %: 0.62
Atmospheric residue (369°-FBP)
Yield on crude, wt %: 13.30
Yield on crude, vol %: 12.35
Density at 15° C., kg/l.: 0.8429
Total sulfur, wt %: 0.026
Total nitrogen, ppm (wt): 10.0
Basic nitrogen, ppm (wt): 3.700
Acidity, mg KOH/g: 0.050
Vis. at 60° C., cst: 9.8430
Vis. at 100° C., cst: 4.3100
Vis. at 120° C., cst: 3.245
Pour point, °C.: 57
Wax, wt %: 54.0
Carbon residue, wt %: 0.08
Vanadium, ppm (wt): < 1
Nickel, ppm (wt): < 2
Iron, ppm (wt): 1
Vacuum residue, 509°-FBP
Yield on crude, wt %: 1.60
Yield on crude, vol %: 1.45
Density at 15° C., kg/l.: 0.8694
Total sulfur, wt %: 0.044
Total nitrogen, ppm (wt): 28.0
Basic nitrogen, ppm (wt): 9.300
Acidity, mg KOH/g: 0.110
Vis. at 60° C., cst: 17.1800
Vis. at 100° C., cst: 10.980
Vis. at 120° C., cst: 6.415
Pour point, °C.: 81
Wax, wt %: 32.0
Carbon residue, wt %: 0.59
Asphaltenes, wt %: 0.15
Vanadium, ppm (wt): 1
Nickel, ppm (wt): 5
Iron, ppm (wt): 8
550°-FBP
Yield on crude, wt %: 0.80
Yield on crude, vol %: 0.70
Density at 15° C., kg/l.: 0.8819
Total sulfur, wt %: 0.049
Total nitrogen, ppm (wt): 35.0
Basic nitrogen, ppm (wt): 11.300
Acidity, mg KOH/g: 0.130
Vis. at 60° C., cst: 33.0300
Vis. at 100° C., cst: 19.340
Vis. at 120° C., cst: 10.230
Pour point, °C.: 87
Wax, wt %: 22.0
Carbon residue, wt %: 0.87
Asphaltenes, wt %: 0.20
Vanadium, ppm (wt): 3
Nickel, ppm (wt): 9
Iron, ppm (wt): 16
585°-FBP
Yield on crude, wt %: 0.35
Yield on crude, vol %: 0.30
Density at 15° C., kg/l.: 0.8970
Total sulfur, wt %: 0.054
Total nitrogen, ppm (wt): 42.0
Basic nitrogen, ppm (wt): 12.800
Acidity, mg KOH/g: 0.140
Vis. at 60° C., cst: 44.7300
Vis. at 100° C., cst: 25.070
Vis. at 120° C., cst: 12.640
Pour point, °C.: 96
Wax, wt %: 13.4
Carbon residue, wt %: 1.19
Asphaltenes, wt %: 0.35
Vanadium, ppm (wt): 5
Nickel, ppm (wt): 17
Iron, ppm (wt): 29
