Characterization of Crude Oil

In this part of the book, fundamental chemical information of interest to petroleum chemists is given. The first chapter deals with the main definitions as well as the important properties of crude oil and petroleum products used by petroleum specialists. A short history is given as to how crude oil became the most important power source for our civilization for over thousands of years. 

A short discussion is also given on the ecological consequences of crude oil production and treatment as well as problems that generally arise in the petroleum industry which crude oil chemists have to confront. 

A detailed discussion on the properties of crude oil and crude oil products and some methods for their improvement prepares the reader for the problems the crude oil chemist faces daily. Some early traditional solutions for these problems, which never became popular at the industrial scale, will show the reader that there are many yet-to-be-researched ways to improve the methods for crude oil treatment. This chapter also highlights the general chemistry of crude oil and crude oil products. 

The last chapter (i.e. chapter 2) of Part I deals with modem analytical methods used in crude oil chemistry. Modern and classical methods of petroleum and petroleum products characterization are explained. This chapter is an essential chapter for present and potential crude oil chemists since analytical chemistry constitutes an important part of crude oil chemistry. Besides, crude oil products have so many special properties that are important for the industry. The need to determine these properties gives rise to the very many analytical methods used in petroleum chemistry. 

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Characterization of Crude Oils According to Dominant Characteristics Based on Overall Physical Properties... 

Characterization of Crude Oils and Petroleum Fractions Based on Structural Analysis... 

Chapters. CHARACTERIZATION OF CRUDE OILS AND PETROLEUM FRACTIONS... 

The preceding discussion on the role of refining and the development of flow schemes shows clearly the importance attributed to the characterization of crude oils and petroleum products. 

D. Vazquez, J. Escobedo, and G. A. Mansoori, Characterization of crude oils from southern mexican oilfields, in Proceedings of the EXITEP 98, International Petroleum Techniques, Exhibition, Placio de Eos Deportes, 15—18 November 1998, Mexico City, Mexico. 

Characterization of Crude Oils and Containants. The first step in selection of emulsion breakers is to obtain as complete an understanding as possible about the crude oil or emulsion. Density (or API gravity) and BS W ranges should be determined. The crude oil should be classified as asphaltic or paraffinic, and the asphaltene and paraffin content should be determined. If treatment will occur at a temperature below the paraffin melting point, the cloud point of the crude oil should be determined. This information will aid in selecting the treating temperature. 

Mutelet, F., Ekulu, G. and Rogalski, M. (2002) Characterization of crude oils by inverse gas chromatography./. Chromat., 969, 207-213. 

The aniline point (or mixed aniline point) (ASTM D-611, IP 2) has been used for the characterization of crude oil, although it is more applicable to pure hydrocarbons and in their mixtures and is used to estimate the aromatic content of mixtures. Aromatics exhibit the lowest aniline points and paraffins the highest aniline points. Cycloparaffins and olefins exhibit values between these two extremes. In any hydrocarbon homologous series the aniline point increases with increasing molecular weight. 

Other HSM applications include the combustion of black powder (81), low-temper-ature phase changes of n-alkanes (82), and the characterization of crude oils treated with rheology modifiers (83). 

All the methods used for colloidal characterization of crude oil can be classified as direct and indirect methods. 

The density that is calculated in equation 2.39 is known as absolute density. However, this density is rarely used by crude oil chemists and only in special cases. Relative density is the parameter that is usually used for the characterization of crude oil and its products. Usually, relative density is measured at a reference temperature of 20°C. Relative density is calculated by equation (2.40). 

Liquid chromatography Analysis method used for characterization of crude oil products based on the differential adsorption ability of the product components on an adsorbent. 

Wang Z, Fingas M, Sergy G (1995) Chemical characterization of crude oil residues from an Arctic beach by GC/MS and GC/FID. Environ Sci Technol 29, 2622-2631. 

Oil industry has a long history of application of NMR spectroscopy for characterization of crude oils, products and oil fractions. The methodology has been mainly ID proton- or carbon-detected experiments. Quantitative NMR and NMR experiments have been used in estimation of aromatic, olefin, naphtene and paraffin proportions in the samples. ° A more detailed characterization has been obtained using various ID carbon-detected experiments, like GASPE, CSE, QUAT and DEPT to obtain quantitative CH sub-spectra. " The goal of characterization of the oil fractions and quantification of certain structural features has been to find correlation between these features and the product properties (e.g. viscosity index, pour point). Due to environmental concerns oil companies are nowadays more interested in development of lubricant base oils that have low aromatic and olefin contents. Hydrogenation of unsaturated components also improves the stability of the base oils, which is an important property for the end-product. Quantitative analysis of a saturated oil fraction with NMR is a major challenge. When the oil fraction contains only aliphatic compounds, the spectrum width that contains the resonances narrows to ca. 1 ppm in the NMR spectrum and ca. 50 ppm in NMR spectrum. This causes excessive... 

Other applications. Over recent years TLC-FID technology has been used by researchers in the petrochemical industry as well as by environmental monitoring groups. Workers in these fields realized the capability of TLC-FID for rapid sample synoptic surveys and screening routines. Most of this work was focused on the rapid characterization of crude oils, coal and petroleum products and the basic characterization of petroleum-contaminated soils. A discussion of TLC-FID applications to petrochemical... 

Hidajat, K Chong, S.M., Quality Characterization of Crude Oils by Partial Least Square Calibration of NIR Spectral profiles , J. Near Infrared Spectrosc., 2000, 8, 53-59. 

The aim of this book is to discuss the many topics related to crude oil. It includes five sections. The first section deals with asphaltenes-these are natural surfactants that stabilize petroleum emulsions. The chapters of the second section discuss some advanced methods used in characterization of crude oil and it s components. The third section includes and publishes new discoveries and improvements in crude oil biology. The fourth section discusses the natural components presented in crude oil and those factors affecting crude oil stability. The final chapter involves some innovative ideas and concepts related to the crude oil. 

Compared to refined products such as gasoline and aviation turbine fuel, there is relatively little in the literature on the analysis and characterization of crude oils. Indeed, for many years, there were relatively few ASTM methods specific to crude oils, although a number of ASTM methods had been adapted for use in analyzing crudes. This situation may have resulted, at least in part, from the historical tendency of refinery chemists to independently develop or modify analjdical methods specific to their needs and subsequently for the methods to become company propriettiry. In recent years, the unique problems associated with sampling and analysis of crude oils have received more attention, and more methods for determining selected constituents and characteristics of crude oils are now being standardized. 

To guarantee that both the experimental distillations and the characterizations of crude oil and its fractions are correct, mass balances have to be performed. In other words, the amount of distilled crude oil must be equal to the sum of amounts of all distillates, the amount of sulfur in crude oil must be equal to the sum of amounts of sulfur in distillates, and so on for some other properties. Figure 1.13 shows the global mass balance and the sulfur balance during distillation of the 13°API crude oil. The differences obtained from these mass balances are quite small and acceptable, and are due to experimental errors during distillation and analysis. 

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