RAW MATERIAL BASE FOR THE DEVELOPMENT OF PETROCHEMISTRY IN WESTERN SIBERIA

N. M. SMOLYANINOVA, A. M. FROLOV, S. I. SMOLYANINOV

(Presented by the scientific-methodological seminar of KhTF)

One of the most urgent questions connected with the priority tasks of developing the oil and gas fields of Tomsk Oblast is the study of the physical properties and material composition of oils and gas condensates, as well as of individual directions in oil refining and petrochemistry. This is explained by the fact that the volume and assortment of petrochemical products are determined both by the needs of the national economy and by the quality of the initial raw material.

It is known that at the present time work has already begun on the construction in Tomsk Oblast of the largest petrochemical complex in the country. Among other regions of Western Siberia, our oblast is especially promising from the standpoint of the possibility of organizing new petrochemical production facilities. This is due to a whole series of technical and economic factors, among which should be noted such factors as proximity to sources of electric power, enormous reserves of cheap solid fuel, practically unlimited sources of water supply, and, most importantly, enormous resources of hydrocarbon raw materials in the form of associated gases from the Soviet oil field and adjacent oil fields of the Nizhne-Vartovsk district of Tyumen Oblast, as well as gas condensate and heavy hydrocarbon gases from the gas-condensate fields of Vasyugan. Since 1966, research in this direction has been carried out by the Department of Chemical Technology of Fuels and by the problem laboratory for the comprehensive utilization of peat.

The unified oil-research program includes determination of the most important physical, physicochemical, and chemical properties, determination of certain technological parameters of its processing, and also study of the quality of commercial products: gasolines, diesel and jet fuels, lubricating oils, boiler fuels, etc.

Much attention is devoted to the study of the group and individual hydrocarbon composition of separate fractions and to their characterization as raw material for deep chemical processing (thermal and catalytic cracking, reforming, pyrolysis, etc.).

Under the indicated program, studies have been carried out on oils and gas condensates from the Soviet, Sredne-Nyurol, Sobolinoye, Luginetskoye, Myldzhinskoye, and North Vasyugan fields. Less detailed studies have been made on oils from the Katylga, Moiseevskoye, Lontyn-Yakhskoye, Poludennoye, and Olenye fields, and on the Ust-Silgin gas condensate.

Most West Siberian oils are characterized by a comparatively high gas factor, with an average value of 50 m³ of gas per ton of oil. Associated petroleum gases contain significant quantities of heavy hydrocarbons (from 30 to 50%).

The indicated hydrocarbons (propane, butane) are highly effective raw materials for chemical processing.

An equally important source of raw materials for petrochemistry is the light hydrocarbons of gas-condensate fields; of particular interest in this respect is the Middle Vasyugan gas-and-oil-bearing region of Tomsk Oblast. Here promising gas-and-oil-bearing areas have been identified and a number of large natural-gas fields have been discovered (Myldzhinskoye, Luginetskoye, Severo-Vasyuganskoye). All these fields belong to the gas-condensate type, with an average content of stable condensate of 150 cm³/cm³ of gas.

Condensate is a mixture of light liquid hydrocarbons (80–90% boils up to 200°C), predominantly of the methane–naphthene type.

Unlike typical gas fields, in which the reservoir gas consists almost entirely of methane, gas-condensate fields of the Middle Vasyugan are also characterized by a very substantial content of ethane, propane, and butane in the reservoir gas. Thus, for example, studies carried out at the Tomsk Polytechnic Institute on separation gases, degassing gases, and also stable condensate from individual wells of the Myldzhinskoye, Luginetskoye, and Severo-Vasyuganskoye fields make it possible to determine (by calculation) the content of ethane in the reservoir gas as 3.4–5.6% and of propane–butane hydrocarbons as 3.2–6.4% (by volume).

Consequently, the resources of these hydrocarbons, determined (in accordance with the planned volumes of gas production) in hundreds of thousands of tons, cannot be disregarded when addressing questions of the national-economic use of associated raw materials.

On the basis of possible production volumes of associated products and the available data on their material composition, it appears possible to obtain, by calculation, approximate estimates of the scale of potential resources of hydrocarbon components.

The total potential resources of hydrocarbon components, calculated for the expected volumes of associated petroleum gases in the Middle Ob region and for the products of development of the Middle Vasyugan gas-condensate fields, are determined in the following volumes (Table 1).

According to studies by the Tomsk Polytechnic Institute, the condensates of the Middle Vasyugan gas-condensate fields are of high value as raw material for chemical processing and for obtaining light commercial petroleum products. The total yield of gasoline fractions (boiling up to 200°C) is more than 80%. Gasolines from condensates are distinguished by high susceptibility to tetraethyl lead. The main gasoline fractions, with the addition of TEL at 0.82 g/kg, give an increase in octane number of 15–16 points. With an 80% yield, the resources of gasoline fractions from the initial condensate will amount in 1975 to more than 500 thousand tons, and in 1980 to more than 1 million tons.

The lower cuts of condensate may be regarded as valuable raw material for catalytic reforming. The yield of the 62–140°C fraction is 44.0%. All lower fractions are practically sulfur-free and are characterized by an insignificant aromatics content (0.5–6%). The content of naphthenic hydrocarbons ranges from 26 to 47%, and of paraffinic hydrocarbons from 51 to 74%.

Table 1

Total potential resources of associated hydrocarbon feedstock, thousand tons

It is also possible to use condensates in pyrolysis processes to obtain olefin hydrocarbons. The high content of paraffinic hydrocarbons, the insignificant amount of aromatics, and the very low sulfur content make it possible to evaluate condensate as an effective pyrolysis feedstock.

Thus, the resources of associated products from oil and gas production in Western Siberia should be considered, above all, as a raw-material base for new chemical industries, the location of which here is stipulated by the Directives of the Twenty-Fourth Congress of the CPSU.

These should primarily be chemical industries in whose feedstock balance hydrocarbon raw material occupies the main place. These include plants for synthetic rubber, plastics, polymer materials (polyethylene, polypropylene, polystyrene), and a number of other industries that provide vitally necessary products of organic synthesis.

The ever-growing needs of society for such materials already now pose the task of organizing their production on the broadest scale.

In this respect Western Siberia possesses unlimited possibilities, which no other economic region of the country has.

According to approximate calculations, the resources of associated hydrocarbon feedstock of the Surgut and Nizhne-Vartovsk (together with the Tomsk) groups of oil fields and the Middle Vasyugan gas-condensate fields, even under conditions of partial extraction of hydrocarbons, make it possible, for the period up to 1980, to supply hydrocarbon feedstock to the production of semi-products for petrochemical processes.

The indicated quantities of semi-products make it possible to organize in Western Siberia the largest production in the Soviet Union of polyolefins (polyethylene and polystyrene), production of ethylene and propylene oxides with their further processing, and a number of scarce synthetic materials (butyl and higher alcohols, starting products for obtaining synthetic fibers, commercial aromatic hydrocarbons—benzene, toluene, xylene), etc.

In addition, the raw-material base makes it necessary to organize, alongside those already listed, large-scale production of synthetic rubbers of the isoprene type and other modern grades.

Taking into account the close interdependence of individual chemical industries (a common raw-material base, the transfer of products and semiproducts from some production facilities for processing at others, unified transport and energy supply, and a number of other factors), it is proposed to locate new chemical production facilities in the form of large complexes consisting of groups of enterprises which, according to their profile, ensure to the greatest extent the integrated processing of raw materials and semiproducts.

The urgent organization of measures for the collection, separation, and transport of associated products of oil production is a necessary condition for the economic progress of Western Siberia. At the present stage of developing optimal variants for the use of associated products, in order to select the most effective scheme for their collection, separation, and transport, it is of paramount importance to carry out a broad range of studies of the physicochemical properties and the qualitative and quantitative composition of oils, natural gas, and associated products of their extraction.