ECONOMICS

HYDROCARBON RAW MATERIAL RESOURCES

Ya. G. Sorkin

UDC 553.98.004.18

In the Basic Directions for Growth of the National Economy of the USSR for the period 1976-1980, particular provisions have been made for the better utilization of the raw materials being produced, with more thorough processing of such materials and increases in the yields of finished products; for the petroleum industry, specifically, provisions have been made for reducing the losses of petroleum gases and for the use of 43-45 billion cubic meters of such gases in 1980. Petroleum gases are present in crude oils at the time of production [associated gas]; other petroleum gases are obtained in refining operations. These petroleum gases are valuable hydrocarbon raw materials. In processing petroleum gases in gas plants (the construction of which will be accelerated as provided in the Basic Directions), both individual hydrocarbons and wide cuts are obtained; these are used as petrochemical feedstocks, as domestic fuel, as a replacement for automotive gasoline, and for other purposes. The utilization of petroleum gases and products derived from such gases will give major savings in the national economy. leum

In this connection, there is a need for a strict accounting for the resources of petrogases and for using these resources in the most rational manner.

In the petroleum refining and petrochemical industry, determination of the resources of light hydrocarbons obtained in destructive processing of petroleum cuts and in the primary distillation of crude oil is based on analyses, measurements, and balance calculations; in the petroleum production industry, however, no such accounting is performed. In an oil reservoir, if the bottom-hole pressure is greater than the saturation pressure, the oil exists in a single-phase state. As it moves through the rock to the well bottom and then to the surface and to the primary field separators, part of the light hydrocarbons is evolved, forming petroleum gas. The separation of this gas from the oil is accomplished in trap separators. The quantity of gas formed in the separator and the distribution of light hydrocarbons between the gas phase (petroleum gas) and the liquid phase (trap oil) depends on the separation method and the separation parameters (temperature and ambient pressure), as well as on the crude oil quality (density, vapor pressure of components). The higher the volatility of the components at a given temperature, the greater will be the amount of such components present in the gas phase. For light crudes (Samotlor, Romashkino, etc.), the distribution of total light hydrocarbons between gas and liquid phase is approximately 70/30 for heavy crudes (Arlan, Bondyug, etc.), a 40/60 distribution is typical. The maximum quantity of gaseous hydrocarbons is evolved from the crude oil by single-stage separation and reduction of the pressure to 1 arm. In multistage separation, which is normally used in oil-field practice in order to reduce the costs of transporting the gas to the consumer, the total quantity of evolved gas is smaller, and the density of the trap oil is lower. The separation temperature has a major influence on the amount of gas formed. The higher the separation temperature, the more gas will be evolved from the oil and the greater the content of heavy hydrocarbons in the gas. In the usual oil-field practice, the quantity of hydrocarbons evolved from the crude oil is assumed to represent the resources of petroleum gas, and that part of the light hydrocarbons remaining in the oil is not included in the gas resources. In subsequent storage and transportation of the oil from the separation units in the Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 7, pp. 25-27, July, 1976.

This material is p r o t e c t e d b y copyright registered in the n a m e o f Plenum Publishing Corporation, 2 2 7 West 17th Street, N e w York, N. Y. 10011. N o part o f this publication m a y be reproduced, stored in a retrieval system, or transmitted, in any f o r m or by any means, elec tronic, mechanical, photocopying, microfilming, recording or otherwise, w i t h o u t written permission o f the publisher. A copy o f this article is available f r o m the publisher f o r $ 7.50.

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oil fields, up to the crude oil pump in a refinery processing unit, the light hydrocarbons remaining in the crude are largely lost to the atmosphere. It is not possible to determine these losses with any accuracy, either as a whole or for individual hydrocarbons, since no data are available on the potential content of these materials in the oil-in-place or in the trap oil. The method of determining the oil-field resources of petroleum gas is another important factor in the accuracy of the determination. The usual practice is to perform the calculations on the basis of the working gas factor, which is the volume of gas evolved from 1 metric ton of oil when it is separated at 1 arm and 20~ Calculation owing t o c e r t a i n

o f t h e r e s o u r c e s on t h e b a s i s serious shortcomings involved

of the working gas factor is not accurate, inthis index, specifically:

a) I n c a l c u l a t i o n s b a s e d on t h e w o r k i n g g a s f a c t o r , no a c c o u n t o f l i g h t h y d r o c a r b o n s b e t w e e n t h e w e l l and t h e p r i m a r y s e p a r a t o r .

is

taken of the losses

5) B e i n g d e t e r m i n e d p e r i o d i c a l l y at very long intervals (sometimes as seldom as once in several years), the working gas factor does not reflect the changing oil-field conditions i n v o l v e d i n t h e o i l p r o d u c t i o n a s new w e l l s a r e b r o u g h t i n o r t h e p r o d u c t i o n r a t e s o f e x i s t ing wells are changed. c) D e t e r m i n a t i o n o f t h e g a s f a c t o r r e q u i r e s c o n v e r s i o n t o t h e a c t u a l c o n d i t i o n s ( t e m p e r a t u r e and p r e s s u r e ) f o r e a c h s e p a r a t i o n s t a g e , and t h e r e s u l t i s a f f e c t e d n o t o n l y by i n accuracies in measuring these parameters, but also by inaccuracies due t o t h e a r b i t r a r i n e s s of the conversion method. The inaccuracies can be particularly great in determining the working gas factor for producing oil fields when the reservoir pressure has dropped below the saturation pressure. The inadequate inaccuracy of the working gas factor affects the calculation of the petroleum gas resources in both directions, i.e., toward overestimating and underestimating. Since the calculation of gas resourcesby oil-field workers is performed under conditions of significant losses of gas, for which the workers are answerable, there is a certain subjective element in the determination of this factor, and, in the majority of cases, the calculatedresources represent underestimates. VNIIUS JAil-Union Scientific-Research Institute of Hydrocarbon Raw Material] has taken crude oil samples from certain fields of the USSR for determination of the potential content of light hydrocarbons in the oil-in-place.

On the basis of these data as applicable to specific crude oils and specific conditions of separation, gas factors were calculated, and these were compared with the working gas factors used in the oil fields to calculate the resources of petroleum gas. The comparision showed that all of such working gas factors, with one exception, were lower than the true values. The lack of any reliable data on the potential content of light hydrocarbons in the crude oils being produced has made it impossible to arrive at any correct estimate of the total resources of such hydrocarbons on a nationwide scale. This circumstance has hindered the planning and siting of plants to process and use this type of valuable raw material. There are also distortions in the data on the losses of light hydrocarbons from crude oil during transportation and storage. Approximate calculations performed for the leading economic districts in oil production and refining have indicated that the total useful utilization of the potential resources of light hydrocarbons, both those in the crude oil being produced and those obtained in refinery processing of the oil, is no greater than 40-60%. The remainder is flared or lost in transport andstorage of the crude oil. A considerable part of the light hydrocarbons, including the propane and butanes that remain in the raw Crude and pass on to the process units, is not used efficiently, owing to the lack of any system for collecting the gas removed in the primary distillation of the crude; such gas is burned in the refinery furnaces, which could well be operated on less expensive fuel. 520

SUMMARY The scientific-research institutes of Minnefteprom and Minneftekhimprom SSSR [Ministries of the Petroleum Production Industry and of the Petroleum Refining and Petrochemical Industry of the USSR] have still not developed any unified procedure and have not carried out any calculations of the total resources of light hydrocarbons on the basis of the potential content in the crude oils being produced and the potential amounts to be obtained in the destructive processing of petroleum products in refineries and petrochemical plants. The lack of any unified procedure for calculating these resources has made it impossible to establish the true losses of this most valuable petrochemical raw material or to arrive at optimum siting of capacity with respect to the economic districts of the country that process and consume light hydrocarbons. It would be a desirable step to charge the All-Union Institute of Hydrocarbon Raw Material (VNIIUS) with the following tasks: a) The development of procedures for determining the potential content of light hydrocarbons in the crude oils being produced and in refinery gases, and the comparison of the total balance of production and consumption of these hydrocarbons. b) The preparation of a periodical handbook on hydrocarbon raw materials, similar to the handbook that has been published on Soviet crude oils, to include the available research material from plant and oil-field laboratories and related institutes.

ECONOMIC EFFECTIVENESS OF I ~ R O V E M E N T S IN BOILER FUEL QUALITY S. A. Feigin, L. M. Noreiko, and E. N. Lebedeva

UDC 662.753.325:666.42:65.018.2

Currently, protection of the atmosphere from pollution is an extremely acute, worldwide problem. A considerable contribution to solving this problem can be made by improvements in boiler fuel quality, in particular through reductions in sulfur content. Numerous investigators have proposed a variety of methods for reducing the discharge of sulfur compounds to the atmosphere due to the use of sulfur-containing boiler fuels. These methods involve either treating the boiler fuel to remove the sulfur in the refinery itself, preliminary gasification of the residual fuel oil with subsequent treatment of the gas to remove sulfur compounds and combustion of the purified gas in an electric power generating station, or removal of the SO2 from the flue gas produced in the combustion of the sulfurcontaining fuel oil. All these variants have been worked out quite thoroughly as to process technology, have been generally debugged, and have been put into service on a commercial scale in some instances. However, widespread use of these approaches is encountering problems, mainly due to the complex processing schemes that are required and the large capital and operating expenses that are incurred [i]. In the present article, we will examine the economic efficiency of different variants in improving boiler fuel quality in the refinery itself. VNII NP [All-Union Scientific-Research Institute for Petroleum Processing] has carried out a series of research studies directed toward determining the economic efficiency in producing boiler fuels with reduced sulfur content through different processing variants. In those studies, however, the economic efficiency in the utilization of boiler fuels with various sulfur contents and with changes in other quality indices (ash content, viscosity, etc.) was almost entirely ignored.

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 7, pp. 27-29, July, 1976. This material is p r o t e c t e d b y copyright registered in the n a m e o f Plenum Publishing Corporaffon, 227 West 1 7th Street, N e w York, N. Y. 10011. N o part o f this publication m a y be reproduced, stored in a retrieval system, or transmitted, in any f o r m or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, w i t h o u t written permission o f the publisher. A copy o f this article is available f r o m the publisher f o r $ Z 5 0 .

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