Study of Gas Condensate from the North-Silginskoye Field
Abstract Generated abstract
This study characterizes gas condensate from the North-Silginskoye field in Tomsk Oblast through fractional distillation, physicochemical measurements, and group and structural group hydrocarbon analysis. The condensate is a light, low sulfur, resin free material dominated by paraffinic hydrocarbons, with smaller naphthenic and aromatic fractions whose proportions vary with boiling range. The analysis identifies potential uses of the main cuts: gasoline fractions may serve as motor gasoline components or pyrolysis feedstock, jet fuel fractions meet some key requirements but are limited by crystallization behavior, a kerosene cut shows good photometric quality, and the residue above 200°C meets summer diesel fuel specifications.
Full Text
STUDY OF GAS CONDENSATE FROM THE SEVERO-SILGINSKOYE FIELD
K. K. STRAMKOVSKAYA, G. B. NEMIROVSKAYA, T. F. BULYCHEVA
(Presented by the scientific-methodological seminar of the organic departments of the Faculty of Chemical Technology)
The field area, in tectonic terms, is located in the northern part of the Silginsk dome-shaped uplift, north of the Ust-Silginskoye gas-condensate field. Territorially, it is situated on the lands of Kargasok District, Tomsk Oblast.
The Severo-Silginsky gas condensate has a low density \((\rho_4^{20} — 0.7411)\), is characterized by insignificant sulfur content \((0.02\%)\), and contains no resinous substances; the distillation up to \(150^\circ\mathrm{C}\) amounts to \(54.0\%\), and up to \(200^\circ\mathrm{C}\) to \(67.5\%\) by weight.
Data on the fractional composition (rectification on an ARN-2 apparatus) and curves characterizing the qualities of 3% fractions of the condensate, preliminarily stabilized at \(28^\circ\mathrm{C}\), are given in Fig. 1.
Tables 1 and 2 present data on the group and structural-group composition of the fractions. It is evident from the tables that the condensate contains 9% aromatic hydrocarbons, 18% naphthenic hydrocarbons, and 73% paraffinic hydrocarbons. With increasing boiling temperature of the fractions, the amount of aromatics increases from 3% in the 60–95°C cut to 20% in the 300–340°C cut. It is characteristic that 3 middle fractions of this condensate (from 122 to 250°C) differ very little from one another in their content of aromatic hydrocarbons. The amount of cyclanes decreases sharply on going to the fraction above 250°C.
According to the data on structural-group composition (Table 2), it may be noted that cyclic hydrocarbons are represented mainly by naphthenic rings.
Narrow gasoline fractions (Table 1) are characterized by an insignificant sulfur content, a comparatively low amount of naphthenic hydrocarbons (35–10%), and a considerable amount of aromatic hydrocarbons (4–13%), which, apparently, does not permit them to be considered a good feedstock for catalytic reforming. The fractions studied may be used for pyrolysis in order to obtain lower olefins.
The characteristics of products of straight-run distillation (commercial products) are given in Table 3.
The gasoline fractions are distinguished by the absence of sulfur compounds and by low octane numbers in neat form, 47–71 (motor method). They may be used as components of motor gasolines.
Fig. 1. Distillation curves of the Severo-Silginskoye gas condensate
Visible labels in the figure:
- \(d_4^{20}\)
- \(n_D^{20}\)
- \(t,^\circ\mathrm{C}\), at 760 mm [[unclear]]
- Yield based on condensate, wt. %
- Sulfur content, %
- Pour point, \(^{\circ}\mathrm{C}\)
Curve labels visible in the plot include: \(n_D^{20}\), \(d_4^{20}\), \(S\), \(\nu_{20}\), \(t_{\mathrm{b.p.}}\), \(t_{10}\), \(t_{50}\), \(t_{90}\), and \(t_{\mathrm{e.p.}}\).
Table 1
Group hydrocarbon composition of gasoline fractions
| Fraction, °C | Yield, % on crude oil | Aromatic hydrocarbons, wt.% | Naphthenic hydrocarbons, wt.% | Paraffinic hydrocarbons of normal structure, wt.% | Paraffinic hydrocarbons of iso structure, wt.% |
|---|---|---|---|---|---|
| 28—60 | 13.9 | absent | absent | 48 | 52 |
| 60—95 | 21.2 | 3 | 36 | 28 | 33 |
| 95—122 | 8.7 | 7 | 35 | 22 | 36 |
| 122—150 | 8.4 | 10 | 19 | 19 | 52 |
| 150—200 | 12.7 | 11 | 12 | 27 | 50 |
| 28—200 | 64.9 | 5 | 21 | 30 | 44 |
| 62—85 | 13.6 | 4 | 32 | 27 | 37 |
| 62—105 | 24.4 | 5 | 34 | 28 | 33 |
| 85—120 | 15.0 | 7 | 35 | 26 | 32 |
| 85—180 | 32.6 | 10 | 23 | 28 | 39 |
| 105—120 | 4.2 | 8 | 28 | 22 | 42 |
| 105—140 | 10.6 | 11 | 21 | 25 | 43 |
| 120—140 | 6.4 | 13 | 16 | 27 | 44 |
| 140—180 | 11.2 | 12 | 10 | 30 | 48 |
Table 2
Physicochemical properties and group hydrocarbon composition of fractions boiling above 200°C
| Indicators | 200—250°C | 250—300°C | 300—k.k. |
|---|---|---|---|
| 1 | 2 | 3 | 4 |
| Yield, wt.% | 9.0 | 6.7 | 12.9 |
| Density, $\rho_4^{20}$ | 0.8045 | 0.8215 | 0.8480 |
| Molecular weight | 185 | 225 | 268 |
| Pour point, °C | −28 | −8 | 6 |
| Viscosity, cSt at 20°C | 3.40 | 5.80 | 18.00 |
| 50°C | 1.90 | 2.90 | 6.80 |
| Sulfur content, % | 0.015 | 0.030 | 0.058 |
| Hydrocarbon content, %: paraffin-naphthenic | 89 | 84 | 80 |
| aromatic | 11 | 16 | 20 |
| including: group I | 8 | 9 | 12 |
| group II | 3 | 2 | 3 |
| group III | absent | 5 | 5 |
| Resins and intermediate fractions | absent | absent | absent |
| Carbon distribution, %: $C_a$ | 1 | 3 | 12 |
Continuation of Table 2
| 1 | 2 | 3 | 4 |
|---|---|---|---|
| \(C_{\mathrm{n}}\) | 37 | 29 | 26 |
| \(C_{\mathrm{p}}\) | 62 | 68 | 62 |
| Number of rings in the molecule: | |||
| \(K_{\mathrm{a}}\) | 0.02 | 0.08 | 0.39 |
| \(K_{\mathrm{n}}\) | 0.86 | 0.81 | 0.89 |
| \(K_{\mathrm{tot}}\) | 0.88 | 0.89 | 1.28 |
Characteristics of commercial products from gas condensate
| Fraction, °C | Yield, % of condensate | Density, \(\rho_4^{20}\) | Viscosity, cSt, at 20°C | Viscosity, cSt, at 50°C | Sulfur content, % | Pour point | Flash point in closed cup |
|---|---|---|---|---|---|---|---|
| Gasoline | Gasoline | Gasoline | Gasoline | Gasoline | Gasoline | Gasoline | Gasoline |
| 28—85 | 28.1 | 0.6845 | — | — | none | — | — |
| 28—120 | 43.1 | 0.7100 | — | — | " | — | — |
| 28—150 | 52.2 | 0.7205 | — | — | " | — | — |
| 28—200 | 64.9 | 0.7320 | — | — | " | — | — |
| Jet fuel | Jet fuel | Jet fuel | Jet fuel | Jet fuel | Jet fuel | Jet fuel | Jet fuel |
| 120—240 | 29.4 | 0.7760 | 1.38 | 5.22* | 0.010 | — | 27 |
| 120—280 | 39.0 | 0.7845 | 1.65 | 6.86* | 0.011 | — | 29 |
| Kerosene | Kerosene | Kerosene | Kerosene | Kerosene | Kerosene | Kerosene | Kerosene |
| 150—280 | 25.9 | 0.7990 | — | — | 0.012 | — | 47 |
| 150—320 | 30.7 | 0.8030 | — | — | 0.015 | — | 53 |
| Diesel fuel | Diesel fuel | Diesel fuel | Diesel fuel | Diesel fuel | Diesel fuel | Diesel fuel | Diesel fuel |
| Residue above 200 | 28.6 | 0.8214 | 5.03 | 2.63 | 0.028 | −23 | 100 |
| Residue above 240 | 21.0 | 0.8327 | 7.97 | 3.75 | 0.85 | −13 | 130 |
* Viscosity at −40°C.
The most important characteristics of jet fuels are heat of combustion and density. According to these indices, the 120—240°C and 120—280°C fractions fully meet the specified requirements. They have a high density (0.7760—0.7845) and, upon combustion, release a large amount of heat (10370—10340 kcal/kg). However, because of the very high initial crystallization temperature (−52, −43), they
can serve only as components in the manufacture of specification-grade fuels for DRV.
From the Severo-Silginskoye condensate it is possible to obtain illuminating kerosene (yield 30.7%) with good photometric quality (height of the non-smoking flame 29 mm).
The residue boiling above 200°C (yield 28.6%) meets, in all indicators, the GOST requirements for summer diesel fuel.
The higher-boiling cut (above 240°C) crystallizes at a high temperature (cloud point −2°C) and cannot be recommended as a diesel fuel.
Table 3
Severo-Silginskoye field
| Product | Temperature, °C: cloud point | Temperature, °C: onset of crystallization | Iodine number, g I₂ per 100 g of fuel | Octane number, neat | Cetane number | Aromatic hydrocarbons content, % | Coking tendency, % | Height of non-smoking flame, mm | Acidity, mg KOH per 100 ml of fraction |
|---|---|---|---|---|---|---|---|---|---|
| fractions | — | — | — | 70.7 | — | absent | — | — | absent |
| fractions | — | — | — | 63.2 | — | 4 | — | — | 0.53 |
| fractions | — | — | — | 57.0 | — | 5 | — | — | 0.89 |
| fractions | — | — | — | 47.0 | — | 5 | — | — | 0.97 |
| fuel | — | −52 | 0.47 | — | — | 11 | — | does not smoke | 0.58 |
| fuel | — | −43 | 0.63 | — | — | 12 | — | ” | 0.73 |
| distillates | −34 | — | — | 21 | — | 13 | — | 30 | 1.07 |
| distillates | −25 | — | — | 18 | — | 14 | — | 29 | 1.26 |
| fuel | −8 | — | 0.81 | — | more than 59 | — | 0.01 | — | 17.59 |
| fuel | −2 | — | 1.22 | — | more than 50 | — | 0.02 | — | 4.49 |