Commercial Properties of Oil from the Samotlor Field
Abstract Generated abstract
This study evaluates the commercial properties of straight-run fractions and residues from Samotlor crude oil through distillation, physicochemical characterization, hydrocarbon composition analysis, and adsorption separation. The results indicate that light gasoline fractions can meet requirements for A-66 motor gasoline after tetraethyllead addition and can also serve as feedstock for high-octane gasoline, while substantial yields of jet fuel, illuminating kerosene, and summer diesel fuels satisfy relevant standards after appropriate refining or treatment. Heavier fractions are characterized as suitable feedstocks for catalytic and thermal cracking, and adsorption data suggest recoverable distillate and residual oil components with specified viscosity indices. The work also identifies possible production of several fuel-oil grades from residues, with reported yields depending on withdrawal depth.
Full Text
Commercial Properties of Oil from the Samotlor Field
K. K. Stramkovskaya, N. M. Smolyaninova, G. S. Goman
(Submitted by the scientific-methodological seminar of the organic departments of the Chemical-Technological Faculty)
The commercial properties of oil from the Samotlor field have been investigated. The main indices characterizing the commercial products of this oil are given in Table 1.
| Cut selection temperature, °C | Yield based on oil, % | Density $\rho_4^{20}$ | Viscosity, cSt, 20°C | Viscosity, cSt, 50°C | Viscosity, cSt, −40°C | Total sulfur content, % | Characteristic: solidification temperature | Characteristic: flash point in closed cup |
|---|---|---|---|---|---|---|---|---|
| n.b.—85 | 6.9 | 0.6826 | — | — | — | absent | — | — |
| n.b.—120 | 11.9 | 0.7125 | — | — | — | absent | — | — |
| n.b.—150 | 17.7 | 0.7225 | — | — | — | absent | — | — |
| n.b.—200 | 26.3 | 0.7495 | — | — | — | absent | — | — |
| Gasoline | ||||||||
| 120—240 | 22.0 | 0.7945 | 1.45 | — | 5.76 | 0.05 | — | 39 |
| 120—280 | 28.9 | 0.8215 | 1.95 | — | 8.75 | 0.05 | — | 41 |
| Fuel for | ||||||||
| Kerosene | ||||||||
| 150—280 | 23.1 | 0.8225 | — | — | — | 0.15 | — | 65 |
| 150—320 | 30.8 | 0.8315 | — | — | — | 0.25 | — | 67 |
| Diesel | ||||||||
| 150—350 | 37.0 | 0.8418 | 4.10 | 1.47 | — | 0.40 | −30 | 70 |
| 200—350 | 28.4 | 0.8515 | 5.80 | 1.63 | — | 0.60 | −21 | 109 |
| 240—350 | 20.8 | 0.8600 | 8.00 | 2.06 | — | 0.78 | −14 | 125 |
| Feedstock for catalysis | ||||||||
| 350—440 | 16.6 | 0.9125 | — | 21.55 | — | 1.48 | 18 | — |
Gasoline fractions of Samotlor crude oil are characterized by the absence of sulfur compounds and by low octane numbers in the neat form (43–66), which is a consequence of the high content of paraffinic hydrocarbons in them (64%). However, the susceptibility of these fractions to tetraethyllead is very high. Fractions from the initial boiling point to 160°C, after the addition of 0.82 g/kg TEL, become suitable for use as A-66 motor gasoline (GOST 2084—56). Higher-boiling fractions have an octane number below 66 when the above-mentioned amount of ethyl fluid is added. All fractions can serve as feedstock for obtaining high-octane gasolines or be used as components of motor gasolines.
The most important characteristics of fuels for turbojet engines are the heat of combustion and density, which determine the possible flight range of an aircraft for a given volume of fuel tanks. In terms of these indicators, the 120—240°C and 120—280°C fractions fully meet the necessary requirements. They have a sufficiently high density (0.7945—0.8215) and, upon combustion, release a large amount of heat (10300—10250 kcal/kg). The hydrocarbon composition of these fractions is also favorable: the content of aromatic hydrocarbons, which increase carbon formation in the engine, is very small (8.4—8.5%). These fractions are characterized by an insignificant content of sulfur compounds and have high stability, but they are distinguished by an elevated initial crystallization temperature and acidity.
Table 1
commercial products
| Product | Cloud point, °C | Initial crystallization temperature, °C | Iodine number, g iodine per 100 g fuel | Octane number | Cetane number | Aromatic hydrocarbons, % | Naphthenic hydrocarbons, % | Paraffinic hydrocarbons, % | Coking tendency, % | Height of non-smoking flame, mm | Acidity, mg KOH per 100 ml fraction |
|---|---|---|---|---|---|---|---|---|---|---|---|
| fractions | — | — | — | 65.7 | — | — | — | — | — | — | 0.43 |
| fractions | — | — | — | 56.8 | — | — | — | — | — | — | 0.48 |
| fractions | — | — | — | 51.1 | — | — | — | — | — | — | 0.62 |
| fractions | — | — | — | 42.9 | — | 11.0 | 25.0 | 64.0 | — | — | — |
| jet-engine fuels | — | −54 | 0.08 | — | — | 8.4 | — | — | — | 26 | 0.81 |
| jet-engine fuels | — | −48 | 0.16 | — | — | 8.5 | — | — | — | 25 | 1.15 |
| distillates | −25 | — | — | 21 | — | — | — | — | — | 24 | 1.00 |
| distillates | −20 | — | — | 19 | — | — | — | — | — | 23 | 1.10 |
| fuels | −13 | — | 0.31 | — | 50.6 | — | — | — | 0.01 | — | 1.45 |
| fuels | −10 | — | 0.52 | — | 51.4 | — | — | — | 0.01 | — | 1.63 |
| fuels | −9 | — | 0.30 | — | 53.1 | — | — | — | 0.01 | — | 2.06 |
| thermal cracking | — | — | — | — | — | 53.1 | 44.6 | — | 0.01 | — | — |
Apparently, after alkaline refining and the addition of special additives that lower the crystallization temperature, these fractions will fully comply with GOST 10 227—62 for grades T-1, T-2, and TS-1 fuel for air-jet engines.
Illuminating kerosene can be obtained from Samotlor crude oil with a yield of 30%. The low octane numbers (21—19) do not allow the kerosene fractions of this oil to be recommended as tractor fuel.
Diesel-fuel fractions are characterized by high cetane numbers and elevated freezing and cloud points owing to the presence in their composition of a large quantity of paraffinic hydrocarbons. They have low coking tendency and low sulfur content. The 150—350°C and 200—350°C fractions meet the requirements for summer diesel fuel of grades DL and DS (GOST 4749—49), as well as for fuels L and S (GOST 305—62). The 240—350°C fraction, by all indices, satisfies GOST 1667—51 for diesel fuel of grades DT-1, DT-2, and DT-3 for medium-speed and low-speed engines.
The 350—440°C fraction is a favorable feedstock for catalytic cracking. It contains 44.6% paraffinic hydrocarbons and 53.1% aromatic hydrocarbons. It contains only a small amount of polycyclic aromatic hydrocarbons and resinous substances, which cause increased coke formation on the catalyst (group IV aromatic hydrocarbons 5.4%, resinous substances 2.3%). The coking tendency of this fraction, which is an indirect characteristic of the feedstock’s propensity for coke formation during catalytic cracking, is very low—0.01%. Catalyst-deactivating impurities such as vanadium are present in extremely small quantities (traces); at the same time, nitrogen compounds are present in increased amounts (nitrogen 0.25%).
The characteristics of the residues for secondary processes are shown in Table 2. These data make it possible to determine the potential yield of gasoline when designing cracking units, and also to determine the tendency of this feedstock toward coke formation.
Table 2
Characteristics of residues for secondary processes
| Withdrawal temperature, °C | Density, $d_4^{20}$ | Kinematic viscosity at 100°C | Pour point, °C | Coking tendency, % | Vanadium, % | Sulfur, % | Elemental composition, %: carbon | Elemental composition, %: hydrogen | Elemental composition, %: nitrogen | Elemental composition, %: oxygen | Yield on crude oil, % |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Above 350 | 0.9350 | 17.8 | 11 | 7.6 | 0.0010 | 1.51 | 86.94 | 10.96 | 0.47 | 0.11 | 43.2 |
| Above 440 | 0.9891 | 97.0 | 33 | 8.9 | 0.0028 | 1.65 | 87.00 | 10.65 | 0.55 | 0.15 | 26.6 |
The results of adsorption separation on silica gel of the 350—440°C fraction and of the residue boiling above 440°C, given in Figs. 1 and 2, show the potential content of high-quality oils in this feedstock. As is seen from Fig. 1, 8.3% distillate oils with a viscosity index of 85 and a pour point of −22°C, calculated on crude oil, can be isolated.
The residual oils (Fig. 2) are very viscous. From the residue boiling above 440°C, 9.0% oils, calculated on crude oil, can be isolated with a viscosity index of 74 and viscosity at temperatures of 50 and 100°C, respectively,
but 307.2 cSt and 30.9 cSt. The pour point of such an oil is \(-3^\circ\text{C}\). Evidently, the residues of Samotlor crude oil may serve as feedstock for the production of high-viscosity oils for turboprop engines.
The characteristics of residues of different depths of withdrawal (Fig. 3) show—
Fig. 1. Curves of the dependence of oil properties on the depth of adsorption separation of the \(350\text{–}440^\circ\text{C}\) fraction of Samotlor crude oil
—that fuel oils of grades \(-40\), 100, and 200 can be obtained from this crude, with yields of 38.0, 32.0, and 31.5%, respectively.
Conclusions
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Straight-run fractions of Samotlor crude oil have been investigated as commercial products.
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It has been shown that gasoline fractions from the initial boiling point to \(160^\circ\text{C}\) meet the GOST standard for A-66 automobile gasoline and may serve as feedstock for the production of high-octane gasolines.
Fig. 2. Curves showing the dependence of oil properties on the depth of adsorption separation of the residue above 440°C from Samotlor crude oil.
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From this crude oil, a large quantity (22–29%) of fuel of grades T-1, T-2, and TS-1 for air-breathing jet engines can be obtained.
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The kerosene distillates (yield 30.8%) meet the GOST requirements for illuminating kerosene.
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From the 150–350 and 200–350°C fractions, summer diesel fuel can be obtained both for high-speed and for low-speed diesel engines.
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The 350–440°C fraction is a good feedstock for catalytic cracking and for the production of oils. The potential content of distillate oils with V.I. is 8.5–8.3%.
Fig. 3. Characteristics of residues of Samotlor oil.
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The residue boiling above 440°C is characterized as a favorable feedstock for thermal cracking, and the potential content of residual oils in it has been shown to be 9.0% with V.I.—74.
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Residues of various sampling depths were studied, and it was shown that from Samotlor oil it is possible to obtain fuel oils of grades 40, 100, and 200 with yields of 38.0, 32.0, and 31.5%, respectively.