Investigation of Gas Condensates from Fields in Tomsk Oblast
Abstract Generated abstract
This study characterizes gas condensates from the Ust-Silga and Myldzhino fields in Tomsk Oblast using physicochemical measurements, fractional distillation, gas chromatography of dissolved gases, and group hydrocarbon analysis of gasoline-range fractions. Both condensates are light, essentially sulfur-free, and rich in gasoline fractions, with the Myldzhino sample showing a particularly high yield below 200°C and the Ust-Silga sample containing dissolved gases dominated by propane and butanes. The group analyses indicate low aromatic contents and substantial paraffinic components, with notable naphthenic content in some light Ust-Silga fractions. The authors conclude that these condensates are better suited as petrochemical pyrolysis feedstock and sources of selected light petroleum products after stabilization than as commercial gasoline components.
Full Text
STUDY OF GAS CONDENSATES FROM FIELDS IN THE TOMSK REGION
N. M. Smolyaninova, S. I. Smolyaninov, N. N. Kostyukova,
V. A. Kuznetsova
(Presented by the scientific-methodological seminar of the Faculty of Chemical Technology)
Gas condensates from the Ust-Silga (well No. 4) and Myldzhino (well No. 15) fields of the Tomsk Region were studied.
The Ust-Silga gas-condensate field was discovered in the summer of 1962. The drilled well produced a gas fountain of 100,000 m³ per day and more than 12 tons of condensate, with the latter content in the gas equal to 112–144 cm³/m³.
The gas-condensate pool is confined to the very bottom of the loose Mesozoic sequence in Jurassic deposits. The field is located almost in the center of the Tomsk Region, 50 km southwest of the village of Kargasok.
A condensate sample from well No. 4 was delivered to the problem laboratory in February 1966 in an amount of 0.5 liter.
The perforation depth was 2282–2274 m and 2260–2250 m.
The condensate is a readily mobile, practically colorless liquid.
The Myldzhino gas-condensate field named after the newspaper Trud is located in the Kargasok District, 55 km south of the village of Srednii Vasyugan. The well produced a gas fountain in the amount of 30,000 m³ per day with a condensate content of 100 cm³/m³ of gas.
The pool is confined to Lower and Middle Jurassic deposits. The perforation depth was 2386–2391 m (II target). A gas-condensate sample was taken from the separator of well No. 15.
Below are the results of determining the physicochemical characteristics and fractional composition (distillation according to GOST 2177-59, Table 1) of the Myldzhino gas condensate.
| Characteristic | Value |
|---|---|
| Specific gravity, \(d_4^{20}\) | 0.7019 |
| Refractive index, \(n_D^{20}\) | 1.4019 |
| Molecular weight | 107 |
| Kinematic viscosity, \(\nu_{20}\), cSt | 0.67 |
| Saturated vapor pressure at 38°, mm Hg | 380 |
| Acidity, mg KOH per 100 ml | 0.61 |
| Sulfur content according to GOST 1771-48 | absent |
The low values of specific gravity, viscosity, molecular weight, and also of the initial boiling point are explained by the high content in the condensate of dissolved gases and low-boiling hydrocarbons,
since the sample under study was not subjected to stabilization. The practically complete absence of sulfur and the high yield of gasoline fractions (distillation up to 200°C), equal to 90%, attest to the high quality of the Myldzhino condensate.
Table 1
Fractional composition of the Myldzhino gas condensate
| $T$, °C | Initial boiling point, 26 | 50 | 60 | 70 | 80 | 90 | 100 | 110 | 120 | 130 | 140 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Distillate, vol. % | first drop | 10 | 17.5 | 26 | 33 | 40 | 48 | 55.5 | 62.5 | 68 | 73 |
| $T$, °C | 150 | 160 | 170 | 180 | 190 | 200 | 220 | 250 | 252 | residue | losses |
| Distillate, vol. % | 78.5 | 81 | 84.5 | 86.5 | 83.5 | 5.90 | 91 | 93 | 94 | 2 | 4 |
The increased losses during distillation are also due to the instability of the condensate.
In studying the Ust-Silgino gas condensate, the following were determined: specific gravity, sulfur content, fractional composition, yield and composition of dissolved gases, and the group hydrocarbon composition of the fractions.
The yield of dissolved gases was determined during fractionation of the condensate on a rectification column with an efficiency of 30 theoretical plates. A special gas meter and a trap cooled with an ice–salt mixture to −15°C were used for collecting noncondensing gases and vapors under constant pressure.
Fractions with temperature limits customarily adopted in determining the group hydrocarbon composition of gasoline fractions of oil [1] were collected after the evolution of dissolved gases had ceased. The last fraction (150–200°C) could not be distilled off completely because of insufficient heating of the column still.
The component composition of the dissolved gases was determined on a UKh-1 chromatograph. Group analysis of the condensate was carried out by the aniline-point method, with removal of aromatic hydrocarbons by chromatography on KSM silica gel ground to 100–200 mesh.
The condensate is characterized by a low specific gravity—0.7300—and a practically complete absence of sulfur. The results of the study of the condensate composition are presented in Tables 2–4.
Table 2
Fractional composition of the Ust-Silgino gas condensate
| $T$, °C | 48 initial boiling point | 60 | 70 | 80 | 90 | 100 | 110 | 120 | 130 | 140 | 150 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Distillate, vol. % | first drop | 6 | 11 | 18 | 27 | 37 | 46 | 54 | 58 | 63 | 67 |
| $T$, °C | 160 | 170 | 180 | 190 | 200 | 210 | 220 | 230 | 240 | 250 | 260 |
| Distillate, vol. % | 71 | 75 | 79 | 84 | 87 | 90 | 92 | 95 | 97 | 98.5 |
The data presented show that the Ust-Silgino condensate has a high content of gasoline fractions—about 84%. By
in terms of fractional composition it is most similar to the gas condensates of the Stepanovskoye and Shebelinskoye fields, differing noticeably from them by a lower final boiling point.
Table 3
Composition of the gas dissolved in the condensate
| Components | CH₄ | C₂H₆ | C₃H₈ | C₄H₁₀ | C₅H₁₁ | C₆H₁₄ |
|---|---|---|---|---|---|---|
| Content, vol. % | — | 17.8 | 31.3 | 33.8 | 15.5 | 1.6 |
The content of gas dissolved in the condensate is 2.1%; propane and butanes predominate in its composition, their total amount being 65.1%.
Table 4
Group hydrocarbon composition of the IBP to 165°C fractions of the Ust-Silginsky gas condensate
| Temperature limits for fraction collection, °C | Yield to condensate without C₅, wt. % | Refractive index, \(n_D^{20}\) | Aromatic hydrocarbons, wt. % | Naphthenic hydrocarbons, wt. % | Methane hydrocarbons, wt. % |
|---|---|---|---|---|---|
| IBP—60 | 10.3 | 1.3650 | 0 | 0 | 100 |
| 60—95 | 20.9 | 1.3925 | 1 | 36 | 63 |
| 95—122 | 17.3 | 1.4090 | 4 | 42 | 54 |
| 122—150 | 17.2 | 1.4190 | 8 | 23 | 69 |
| 150—165 | 10.5 | 1.4278 | 6 | 17 | 77 |
| IBP—165 | 76.2 | — | 4 | 26 | 70 |
| 165—FBP | 22.2 | 1.4440 | 11 | 0 | 89 |
The data on the group composition of the condensate, given in Table 4, show that it is distinguished by a very low content of aromatic hydrocarbons. With increasing temperature limits of fraction collection, the amount of aromatics increases from 1% in the 60—95°C fraction to
Table 5
Group hydrocarbon composition of the Myldzhinsky gas condensate
| Temperature limits for fraction collection, °C | Yield to condensate, wt. % | \(n_D^{20}\) | Aromatic hydrocarbons, wt. % | Naphthenic hydrocarbons, wt. % | Paraffinic hydrocarbons total, wt. % | Paraffinic hydrocarbons of normal structure, wt. % |
|---|---|---|---|---|---|---|
| 28—60 | 9.0 | 1.3660 | absent | absent | 100 | 42 |
| 60—95 | 22.6 | 1.3938 | 1 | 35 | 64 | 28 |
| 95—122 | 14.8 | 1.4089 | 2 | 38 | 60 | 22 |
| 122—150 | 13.7 | 1.4178 | 6 | 24 | 70 | 25 |
| 150—200 | 17.2 | 1.4283 | 7 | 17 | 76 | 26 |
| 28—200 | 77.3 | 1.4075 | 3 | 25 | 72 | 29 |
8%—in the 122–150°C fraction, and then decreases. The residue boiling above 165°C contains 11% aromatics and contains no naphthenes at all. Thus, according to group-analysis data, the product studied has no analogues among known gas condensates. It differs from the Khodzhabinsk condensate (with its strongly pronounced methane character) by a very high content of naphthenic hydrocarbons in the fractions up to 150°C and a low content of aromatic hydrocarbons.
The group composition of the Myldzhin condensate is shown in Table 5.
Owing to the small amount of aromatics and naphthenes, the gasoline fractions of the condensates apparently cannot be used as commercial gasolines because of their low octane numbers. However, by all indicators, the indicated condensate fractions are excellent feedstock for pyrolysis for the purpose of producing gaseous monoolefins—petrochemical feedstock. Moreover, the low content of aromatic hydrocarbons is a major advantage of these products as pyrolysis feedstock, since it eliminates the need for fraction dearomatization.
After preliminary stabilization, about 27% of the condensate can be used to obtain “Kalosha” gasoline (GOST 443-56), white spirit, etc., while the higher-boiling fractions can serve as a component of illuminating kerosene and T-1 jet fuel (GOST 4138-49).
The condensate stabilization gases, owing to their high content of the propane–butane fraction, can be used as domestic fuel and are also valuable feedstock for petrochemistry.
REFERENCES
- Guide to the Analysis of Petroleum. Leningrad, Nedra, 1966.
- Ya. D. Savvina. Condensates of Gas-Condensate Fields of the USSR. Proceedings of VNII Gaz, issue 5/13, 1959.
- A. S. Velikovskii, Ya. D. Savvina. Condensates of gas-condensate fields and their processing into light petroleum products. Chemistry and Technology of Fuels and Oils, No. 1, 17–21, 1958.
- Petroleum Products: Properties, Quality, Application. Handbook. Moscow, Khimiya, 1966.