Crude oil classification

A. E. Lichtenstein, H. A. Pattern Recognition of Output from GC-MS-COM for Crude Oil Classification, U.S. Coast Guard, University of Connecticut, IEEE, Proceedings, Workshop on Pattern Recognition Applied to Oil Identification, Coronado, CA, November 1976 IEEE Catalog No. 76 CH 1247-6 C. 

There are a total of eighteen different hydrocarbon series, of which the most common constituents of crude oil have been presented - the alkanes, cycloalkanes, and the arenes. The more recent classifications of hydrocarbons are based on a division of the hydrocarbons in three main groups alkanes, naphthanes and aromatics, along with the organic compounds containing the non-hydrocarbon atoms of sulphur, nitrogen and oxygen. 

As a starting point, the book reviews the general properties of the raw materials. This is followed by the different techniques used to convert these raw materials to the intermediates, which are further reacted to produce the petrochemicals. The first chapter deals with the composition and the treatment techniques of natural gas. It also reviews the properties, composition, and classification of various crude oils. Properties of some naturally occurring carbonaceous substances such as coal and tar sand are briefly noted at the end of the chapter. These materials are targeted as future energy and chemical sources when oil and natural gas are depleted. Chapter 2 summarizes the important properties of hydrocarbon intermediates and petroleum fractions obtained from natural gas and crude oils. 

Fonseca, A.M., et al, Geographical classification of crude oil by Kohonen selforganizing maps, Analytica Chimica Acta, 556, 374, 2006. 

Because of the variations in the quality of crude oils, the flash point of any crude oil it must be tested, however because most crude oils contain a quantity of light vapors they are considered in a low flash point classification. In atmospheric burning heavy smoke production normally occurs. 

A widely used classification of petroleum distinguishes between crude oils either on a paraffin base or on an asphalt base and arose because paraffin wax separates from some crude oils on cooling, whereas other oils show no separation of paraffin wax on cooling. The terms paraffin base and asphalt base were introduced and have remained in common use (van Nes and van Westen, 1951). 

The viscosity-gravity constant and the Universal Oil Prodncts characterization factor have been used to some extent as a means of classifying crnde oils. Both parameters are generally employed to give an indication of the paraffinic character of the crude oil, and both have been nsed, if a snbtle differentiation can be made, as a means of petroleum characterization rather than for petrolenm classification. 

Queste S, Salager JL, Strey R, Aubry JM (2007) The EACN scale for oil classification revisited thanks to fish diagrams. J Colloid Interface Sci 312 98-107 Cayias JL, Schechter RS, Wade WH (1976) Modeling Crude Oils for Low Interfacial tension. Soc Petrol Eng J 16 351-357... 

Petroleum crude oils, which are divided for the purposes of conventional classification into three main types—asphalt (or naphthenic)-base, paraffin-base, and mixed-base—contain varying amounts of hydrocarbons which readily solidify and are identified as wax. The asphalt-base crudes may contain only a trace of wax, while the wax content of the paraffin-base crudes and the mixed-base crudes may be as high as 15% or higher (73). Crude oils with a wax content as high as 35% are known. 

A. M. Fonseca, J. L. Vizcaya, J. Aires-de-Sousa and A. M. Lobo, Geographical classification of crude oils by Kohonen self-organizing maps, Anal. Chim. Acta, 556(2), 2006, 374-382. 

Crude oils are classified chemically according to the structures of tire larger molecules in the mixture. Classification methods use combinations of the words paraffinic, naphthenic, aromatic, and asphaltic. For instance, crude oil which contains a predominance of paraffinic molecules will yield very fine lubricating oils from the gas-oil fraction and paraffin wax from the residuum. Oh the other hand, if the larger molecules are aromatic and asphaltic, the heavier fractions of the crude oil are useful for pitch, roofing compounds, paving asphalts, and other such applications. 

Terms such as paraffinic, naphthenic, naphthenic-aromatic, and aromatic-asphaltic are used in the several classification methods which have been proposed. These terms obviously relate to the molecular structure of the chemical species most prominent in the crude oil mixture. However, such classification is made difficult because the large molecules usually consist of condensed aromatic and naphthenic rings with paraffinic side chains. The characteristic properties of the molecules depend on the proportions of these structures. 

The petroleum industry has not agreed on a standard classification system. Further, the classification of crude oil is of little importance in its production, with the exception that paraffinic crudes can precipitate wax... 

A general classification of oil eg crude oil, petroleum, gas oil, is often satisfactorily achieved by gas chromatographic techniques possibly coupled with mass spectrometry or infrared spectroscopy applied to a sample of the oil pollutant. The true identification invariably requires samples from potential sources for comparison with the pollutant. 

Elemental analyses of petroleum show that it contains mainly carbon and hydrogen. Nitrogen, oxygen, and sulfur (heteroelements) are present in smaller amounts, and trace elements such as vanadium, nickel, etc, are also present. Of the heteroelements, sulfur is the most important. The mixture of hydrocarbons is highly complex. Paraffinic, naphthenic, and aromatic structures can occur in the same molecule, and the complexity increases with boiling range. The attempted classification of crude oils in terms of these three main structural types has proved inadequate. 

Because of the wide range of chemical and physical properties, a wide range of tests have been (and continue to be) developed to provide an indication of the means by which a particular feedstock should be processed. Initial inspection of the nature of the petroleum will provide deductions about the most logical means of refining or correlation of various properties to structural types present and hence attempted classification of the petroleum. Proper interpretation of the data resulting from the inspection of crude oil requires an understanding of their significance. 

Hiihnerfuss H, Alpers W, Fast O, Lange PA, Loffet A, Richter K, Schriel RC, Skou, and Witte F (1987) The discrimination between crude oil spills and monomolecular sea slicks by airborne remote sensors. In Environment and quality of life. The Archimedes 2 Experiment. R.H. Gillot ed., Commission of file European Communities, Eur 11249 EN 167 - 177 Hiihnerfuss H and Alpers W (1987) On the detection and classification of organic chemical compounds on the sea surface by airborne remote sensors. In Proceedings of the 1987 International Colloquium on Remote Sensing of Pollution of the Sea, Oldenburg (FRG). Reuter R and Gillot RH eds., Commission of the European Communities, S.P.L 87.46 441 - 455... 

Crude oils can be classified according to the relative amounts of acyclic alkanes, cycloalkanes and combined aromatic hydrocarbons plus NSO compounds present. This classification is represented by the ternary (triangular) plot in Fig. 4.22, and can be seen to distinguish between the main fields of marine and terrestrially sourced oils. The main classes of normal crudes resulting from this classification are ... 

Fig. 4.22 Classification of crude oils based on distribution of paraffins, naphthenes and aromatics plus NSO compounds (afterTissot Welte 1984).

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