OIL OF THE VAR-EGAN FIELD

K. K. STRAMKOVSKAYA, A. I. LEVASHOVA, G. B. NEMIROVSKAYA,
G. S. VENCHKOVSKAYA

(Presented by the scientific-methodological seminar of the organic departments
of the Faculty of Chemical Technology)

The oil of the Var-Egan field has a low density \((\rho_4^{20} — 0.8552)\), low sulfur content, low viscosity \((\nu_{20} — 9.73\ \text{cSt})\), is resinous (resins—6.7%, asphaltenes—0.9%) and paraffinic (paraffin 3.5%); likewise, like other oils of the Nizhnevartovsk region (Sovetskaya, Samotlor), it has a high content of gasoline fractions; distillation up to \(200^\circ\text{C}\) amounts to 26.5%, and up to \(300^\circ\text{C}\) (according to GOST 2177-59) 49%.

Fig. 1. Distillation curves of Var-Egan oil

The data on fractional composition (rectification on ARN-2) and the curves characterizing the properties of the 3% fractions are shown in Fig. 1.

* Viscosity at −40°C.

The characteristics of the products of straight-run distillation (commercial products) are given in Table 1.

The gasoline fractions are distinguished by the absence of sulfur compounds and by octane numbers in the neat state (51—75) that are somewhat higher than those of other oils of Western Siberia. All distillates from the initial boiling point to 200°C, after addition of ethyl fluid in an amount of 0,82 g/kg, meet the requirements for A-66 gasoline, and with addition of this antiknock agent in an amount of 2,7—3,3 g/kg they can serve as components of aviation gasolines.

A very important property of this oil is also that the fraction boiling within 120—240°C (yield 21,3%) meets the GOST requirements for TS-1 fuel for turbojet engines, while the 120—280°C fraction (yield 28,8%) can be used as T-1 fuel.

From this oil an illuminating kerosene can be obtained (yield 31,4%) with good photometric properties (height of the non-smoking-

Var-Yeganskoye field

Table 1

flame height 21 mm), and the kerosene fractions may also be used as tractor fuel (octane numbers 40—41).

The diesel-fuel distillates are characterized by high cetane numbers (53—54), low sulfur content, and low coking tendency. In terms of cetane numbers, viscosity level, pour point, and the remaining indices, all fractions meet the requirements for summer diesel fuel.

The yield of feedstock for catalytic cracking (350—450°C fraction) is 17.0% on crude oil; it contains 63% naphthenic-paraffinic hydrocarbons and 35% aromatics. This feedstock has low sulfur content and very low coking tendency (0.05%); however, it contains a considerable amount of nitrogen (0.29%) and vanadium (0.003%).

In processing the crude oil, it appears possible to obtain fuel oils of grades 40, 100, and 200 (Table 2), as well as viscous road bitumens.

The characteristics of the fractions that can be used as feedstock for catalytic reforming are given in Table 3. These data show that all fractions are sulfur-free and contain

Characteristics of fuel oils and residues of Baku oils

Table 2

Table 3

Group hydrocarbon composition of gasoline fractions

a significant amount of naphthenic hydrocarbons (38—45%), little aromatic hydrocarbons, and may serve as a good feedstock for catalytic reforming.

Fig. 2. Dependence curves of oil quality on the depth of adsorption separation of the 350—450°C fraction

Fig. 3. Dependence curves of oil quality on the depth of adsorption separation of the 450—500°C fraction

In studying the group hydrocarbon composition of 50-degree fractions boiling above 200°C, the presence of aromatic hydrocarbons in an amount of 26—43% was established (Table 4), while

number, the share of aromatics of group I accounts for 13–21%. Depending on the temperature limits of fraction selection, the content of paraffinic-naphthenic hydrocarbons is 74–55%, decreasing with an increase in the boiling temperature of the fractions. According to the structural-group composition data, it may be noted that the cyclic hydrocarbons of the fractions boiling up to 350°C are represented mainly by monocyclic naphthenes, while in the higher-boiling fractions the number of rings in the molecule does not exceed 2.

Fig. 4. Curves of dependence of oil quality on the depth of adsorptive separation of the residue above 500°C

The potential content and characteristics of distillate and residual oils, determined by the method of adsorptive separation on silica gel according to GOST 11244-65, are shown in Figs. 2, 3, 4. On the basis of these data it may be concluded that Var’yegan crude oil is characterized by a high yield of quality oils with a viscosity index of 85; thus, from the 350–450°C fraction they can be obtained in an amount of 13.8%, and from the 450–500°C fraction, 7.5%. The potential content of residual oils (residue above 500°C) with VI-85 and a viscosity level at 100°C of 30, 30 cSt is 3.7%. The total potential content of oils with VI-85 is equal to 25.0%.

According to the technological classification (GOST 912-66), the oil of the Var’yegan field, in terms of sulfur content, belongs to class I; in terms of the yield of fractions up to 350°C—to the first type; in terms of the potential content of oils—to the first group; in terms of their quality—to subgroup И₁, and in terms of paraffin content—to type П₂. Thus, the code of Var’yegan oil is 1Т₁М₁И₁П₂.

Table 4

Physicochemical properties and group hydrocarbon composition of fractions boiling above 200°C

Continuation of Table 4