Assays for the following Mexican crudes have been updated: Isthmus, Maya, Olmeca, and Marine Light (OGJ, Mar. 4, 1991, p. 45).
Mexico's reserves in the Marine region of Campeche1 at the end of 1999 were 21.3 billion bbl. This region has two types of crude oils: Maya and Marine Light.
The southern part of the states of Tabasco and Chiapas holds 6.0 billion bbl of reserves.1 This region produces Isthmus, Maya, and Olmeca crudes.
Total sales of these four important Mexican crudes in 1999 were 2.9 million b/d. Petróleos Mexicanos (Pemex) refineries received 1.3 million b/d, and Mexico exported the remaining 1.6 million b/d.
Local Mexican refineries process an Isthmus to Maya to Olmeca ratio of 56.8/41.7/1.5. The corresponding export ratio is 12.2/41.7/1.5. The US, Spain,the Netherland Antilles, and Japan imported most Mexican crude.
Isthmus
Isthmus crude has a medium gravity of 32.9° API. It contains about 1.4 wt % sulfur and 46.3 ppm of nickel and vanadium. As it is paraffinic, Ishthmus crude is an excellent feedstock for production of automotive multigrade lube oils.
Fig. 1 shows the true boiling point (TBP) distillation curve and specific gravity contour chart2 for Isthmus crude.
The crude is currently processed in Pemex's Salamanca refinery, which produces high viscosity index lube oils by an extraction processes. In 1999, Mexico produced 950,000 b/d of Isthmus crude, of which 190,000 b/d were shipped from the Pajaritos and Salina Cruz harbors.1
Whole crude
Gravity, °API 32.9
Sulfur, wt % 1.4
Viscosity @ 25° C., cst 8.8
Pour point, °C. -36
Conradson carbon residue, wt % 4.5
Acidity, mg KOH/g 0.46
Vanadium, ppm 38.1
Nickel, ppm 8.2
Asphaltenes, wt % 1.8
Rvp, psi 6.6
UOP K factor 11.95
C4-, vol % 1.3
Naphtha
Boiling range, °F. C5-351
Yield, vol % 25.2
Gravity, °API 65.3
Sulfur, wt % 0.025
Mercaptan sulfur, ppm 54
Rvp, psi 8.7
RON, clear 46.5
Kerosine
Boiling range, °F. 351-526
Yield, vol % 18.3
Gravity, °API 42.9
Sulfur, wt % 0.27
Pour point, °C. -39
Smoke point, mm 26
Viscosity @ 100° F., cst 1.65
Aromatics, vol % 20.1
Light gas oil
Boiling range, °F. 526-651
Yield, vol % 11.9
Gravity, °API 33.4
Sulfur, wt % 1.04
Pour point, °C. -9
Diesel index 52.5
UOP K factor 11.9
Viscosity @ 100° F., cst 5.1
Basic nitrogen, ppm 111
Heavy gas oil
Boiling range, °F. 651-1,000
Yield, vol % 26.7
Gravity, °API 23.1
Sulfur, wt % 1.81
Pour point, °C. 27
UOP K factor 11.8
Viscosity @ 100° F., cst 45.4
Basic nitrogen, ppm 210
Residue
Boiling range, °F. 651+
Yield, vol % 44.3
Gravity, °API 14.6
Sulfur, wt % 2.46
Asphaltenes, wt % 3.6
Viscosity @ 210° F., cst 30.1
Nickel, ppm 16.5
Vanadium, ppm 76.5
Conradson carbon residue, wt % 9.0
Residue
Boiling range, °F. 1,000+
Yield, vol % 16.6
Gravity, °API 6.1
Sulfur, wt % 3.5
Asphaltenes, wt % 7.9
Viscosity @ 210° F., cst
Olmeca
Olmeca is a paraffinic, light crude with a gravity of 38.9° API. It has a nickel and vanadium content of less than 15 ppm. Fig. 2 shows the distillation curve and specific gravity contour chart for Olmeca crude.2
Between 1990 and 1995, the Salamanca refinery processed this Pemex crude to produce high viscosity index lube oils. Typical recent production of Olmeca is 455,000 b/d.1
About 435,000 b/d crude are shipped from the port of Pajaritos.1
Whole crude
Gravity, °API 38.9
Sulfur, wt % 0.93
Viscosity @ 25° C., cst 4.22
Pour point, °C. -45
Conradson carbon residue, wt % 2.8
Acidity, mg KOH/g 0.8
Vanadium, ppm 8.0
Nickel, ppm 2.5
Asphaltenes, wt % 0.95
Rvp, psi 6.6
UOP K factor 12.0
C4-, vol % 1.8
Naphtha
Boiling range, C5-351° F.
Yield, vol % 29.0
Gravity, °API 66.5
Sulfur, wt % 0.017
Mercaptan sulfur, ppm 57
Rvp, psi 8.1
RON, clear 53.3
Kerosine
Boiling range, 351-526° F.
Yield, vol % 19.2
Gravity, °API 43.2
Sulfur, wt % 0.13
Pour point, °C. -42
Smoke point, mm 26
Viscosity @ 100° F., cst 1.6
Aromatics, vol % 18.5
Light gas oil
Boiling range, °F. 526-651.
Yield, vol % 14.8
Gravity, °API 33.7
Sulfur, wt % 0.63
Pour point, °C. -9
Diesel index 53.8
UOP K factor 11.9
Viscosity @ 100° F., cst 5.0
Basic nitrogen, ppm 61
Heavy gas oil
Boiling range, °F 651-1,000
Yield, vol % 24.9
Gravity, °API 23.6
Sulfur, wt % 1.38
Pour point, °C. 30
UOP K factor 11.8
Viscosity @ 100° F., cst 34.5
Basic nitrogen, ppm 238
Residue
Boiling range, 651+° F.
Yield, vol % 35.2
Gravity, °API 18.6
Sulfur, wt % 2.01
Asphaltenes, wt % 2.4
Viscosity @ 210° F., cst
Residue
Boiling range, °F 1,000+
Yield, vol % 10.3
Gravity, °API 8.9
Sulfur, wt % 3.4
Asphaltenes, wt % 7.6
Viscosity @ 210° F., cst 210.8
Nickel, ppm
Maya
Maya crude is a heavy crude with a 21.5° API gravity. Its sulfur content is 3.4 wt %. Both UOP K factor and US Bureau of Mines distillation methods classify this crude as paraffinic and naphthenic. Its vacuum resid produces an excellent grade of asphalt.3 Fig. 3 shows the distillation curve and specific gravity contour chart for Maya crude.2
A blend of Maya with a medium-gravity crude is an attractive feedstock to refining schemes. Since June 1998, the Cangrejera Petrochemical Complex, located in Coatzacoalcos, Veracruz, has processed only Maya crude, about 150,000 b/d.
The facility produces benzene, toluene, and xylenes. Recent production of Maya has been about 1.5 million b/d.1 Mexico ships the crude from the ports of Dos Bocas and Cayo Arcas on the Gulf of Mexico and from Salina Cruz on the Pacific Coast.
Whole crude
Gravity, °API 21.5
Sulfur, wt % 3.4
Viscosity @ 25° C., cst 170.1
Pour point, °C. -30
Conradson carbon residue, wt % 10.8
Acidity, mg KOH/g 0.43
Vanadium, ppm 277.5
Nickel, ppm 52.9
Asphaltenes, wt % .6
Rvp, psi 6.0
UOP K factor 11.70
C5-, vol % 0.3
Naphtha
Boiling range, ° F. C5-351
Yield, vol % 15.3
Gravity, °API 60.4
Sulfur, wt % 0.10
Mercaptan sulfur, ppm 95
Rvp, psi 6.7
RON, clear 50.7
Kerosine
Boiling range, ° F. 351-526
Yield, vol % 13.8
Gravity, °API 40.3
Sulfur, wt % 1.2
Pour point, °C. -39
Smoke point, mm 20
Viscosity @ 100° F., cst 1.82
Aromatics, vol % 33.6
Light gas oil
Boiling range, ° F. 526-651
Yield, vol % 9.4
Gravity, °API 29.7
Sulfur, wt % 2.46
Pour point, °C. 0
Diesel index 54
UOP K factor 11.6
Viscosity @ 100° F., cst 5.7
Basic nitrogen, ppm 199
Heavy gas oil
Boiling range, °F. 651-1,000
Yield, vol % 24.3
Gravity, °API 20.6
Sulfur, wt % 3.25
Pour point, °C. 30
UOP K factor 11.54
Viscosity @ 100° F., cst 61.7
Basic nitrogen, ppm 525
Residue
Boiling range, °F. 651+
Yield, vol % 61.2
Gravity, °API 9.5
Sulfur, wt % 4.70
Asphaltenes, wt % 12.5
Viscosity @ 210° F., cst 610.9
Nickel, ppm 79.3
Vanadium, ppm 407.7
Conradson carbon residue, wt % 16.2
Residue
Boiling range, °F. 1,000+
Yield, vol % 36.9
Gravity, °API 4.0
Sulfur, wt % 5.3
Asphaltenes, wt % 20.5
Viscosity @ 210° F., cst 160,000
Nickel, ppm 125.2
Vanadium, ppm 649.4
Conradson carbon residue, wt % 25.8
Asphalt4 AC-20
Yield, vol % 47.1
Viscosity @ 275° F., cst 468.5
Viscosity @ 140° F., cp 237,600
Flash point temperature, °C. 294
Penetration, 1/10 mm 73
Marine Light
Marine Light crude is produced by several Mexican oil fields-Uech, Caan, Chuc, Taratunich, Pol, Batab, Abkatum, Ek, Balam, and Ixtoc-in the northeast and southwest areas of the Marine Region.
Recent production of Marine Light is about 721,000 b/d.1 Fig. 4 shows the distillation curve for Marine Light.
Whole crude
Gravity, °API 34.5
Sulfur, wt % 1.23
Viscosity @ 25° C., cst 6.71
Pour point, °C. -42
Conradson carbon residue, wt % 3.87
Acidity, mg KOH/g 0.26
Vanadium, ppm 23.9
Nickel, ppm 5.2
Asphaltenes, wt % 2.7
Rvp, psi 7.5
UOP K factor 11.97
C4-, vol % 0.2
Naphtha
Boiling range, °F. C4-351
Yield, vol % 5.1
Gravity, °API 66.2
Sulfur, wt % 0.015
Rvp, psi 5.2
RON, clear 52.02
Kerosine
Boiling range, °F. 351-526
Yield, vol % 20.0
Gravity, °API 42.2
Sulfur, wt % 0.30
Pour point, °C. -39
Smoke point, mm 19
Viscosity @ 100° F., cst 1.73
Aromatics, vol % 20.9
Light gas oil
Boiling range, °F. 526-651° F.
Yield, vol % 12.7
Gravity, °API 32.2
Sulfur, wt % 1.15
Pour point, °C. -6
Diesel index 52.2
UOP K factor 11.82
Viscosity @ 100° F., cst 5.1
Basic nitrogen, ppm 107
Heavy gas oil
Boiling range, °F. 651-1,000
Yield, vol % 25.8
Gravity, °API 23.1
Sulfur, wt % 1.76
Pour point, °C. 30
UOP K factor 11.7
Viscosity @ 100° F., cst 45.47
Basic nitrogen, ppm 323
Residue
Boiling range, °F. 651+
Yield, vol % 42.0
Gravity, °API 17.4
Sulfur, wt % 2.19
Asphaltenes, wt % 5.8
Viscosity @ 210° F., cst 26.8
Nickel, ppm 11.1
Vanadium, ppm 51.3
Conradson carbon residue, wt % 8.3
Residue
Boiling range, °F. 1,000+
Yield, vol % 16.2
Gravity, °API 9.7
Sulfur, wt % 2.8
Asphaltenes, wt % 14.0
Viscosity @ 210° F., cst 389.4
Nickel, ppm 27.3
Vanadium, ppm 125.4
Conradson carbon residue, wt % 20.4
References
- Petróleos Mexicanos, Memoria de Labores, 1999.
- Nelson, W.L, Petroleum Refinery Engineering, 4th ed., 1987.
- Manriquez O., Leonardo, Gómez Z., Jose Luis, Leiva y N., Miguel, et al., "Superasfaltos del crudo Maya," 10th Congreso Iberolatinamericano del asfalto, Madrid, 1999.
- American Society for Testing and Materials Standards, Petroleum Products, vol. 05.02, 1991.
The authors-
Leonardo Manriquez is a project leader at the Instituto Mexicano del Petróleo. He has 15 years' experience in petroleum processing research. Manriquez specializes in asphalt and lube oil processes and characterization of crude oils. He holds a BS in chemical engineering from the Universidad de Guanajuato, Mexico.
Abel Moreno is the head of the refining process division at Instituto Mexicano del Petroleo. His research covers the areas of refining processes, catalysis, and crude oil characterization. Moreno holds a BS in chemical engineering from the Universidad de Guanajuato, Mexico.
Edmundo R. Tenorio is a project coordinator at Instituto Mexicano del Petroleo. He is a specialist in asphalt processes and the characterization of crude oils. Tenorio holds a BS in chemical engineering from Instituto Politecnico Nacional, Mexico City.
David Herrera is a manager for Petróleo Mexicanos Exploracion y Produccion in the Marina Noreste region. He specializes in the offshore transportation and distribution of crude. Herrera holds a BS in chemical engineering from the Universidad Autonoma de Mexico, Mexico City.