Crude Oil Components

Fluid catalytic cracking units (FCC or FCCU) are the major processing units to reduce boiling ranges of those crude oil components that have boiling points higher than the final boiling points of the transportation fuels—typically above 650°F (343°C). These... 

Appreciable property differences appear between crude oils as a result of the variable ratios of the crude oil components. For a refiner dealing with crudes of different origins, a simple criterion may be established to group crudes with similar characteristics. Crude oils can be arbitrarily classified into three or four groups depending on the relative ratio of the hydrocarbon classes that predominates in the mixture. The following describes three types of crudes ... 

CH3)2. CH.CH2.CH3 mw 72.15, colorl liq, mp -159.9°, bp 27.85°, d 0.6201 g/cc at 20/4°, RI 1.35370. Sol in ethanol, ether, hydrocarbons and oils, insol in w. First prepd by Frankland in 1850 by treating iso-amyl iodide with Zn in w at 140° (Ref 2). It was isolated by Young from American petroleum (Ref 3). Present methods of prepn include fractional distn of petroleum and subsequent purification of the crude isopentane by rectification, as well as cracking and reforming of crude oil components and natural gasolines in oil refineries (Refs 4 7)... 

Use of carefully selected surfactants in well treatment fluids is a way to accomplish this. Rock wettability can be altered by adsorption of polar materials such as surfactants and corrosion inhibitors, or by the deposition of polar crude oil components (173). Pressure appears to have little influence on rock wettability (174). The two techniques used to study wettability, contact and and relative permeability measurements, show qualitative agreement (175-177). Deposition of polar asphaltenes can be particularly significant in carbon dioxide enhanced oil recovery. 

Bennett and Barter (1997) discuss the effect of partitioning-dissolution in an aqueous phase of alkylphenol. Specifically, they show that the depletion of this crude oil component affects the chemical composition of the original pollutant. Partitioning at equilibrium can be considered the maximum dissolution value of a compound under optimal solvation conditions. Partitioning-dissolution is obtained by washing the crude oil with saline water at variable temperature and pressure conditions, similar to those in the subsurface. The data reported were obtained using a partition device able to simulate the natural environmental conditions of a crude oil reservoir. The alkylphenol partition coefficients between crude oil and saline subsurface water were measured as a function of variation in pressure, temperature, and water salinity. Preliminary trials proved that the experimental device did not allow alkylphenol losses due to volatilization. 

Before distillation, crude oil salts and certain metals must be removed. The process of desalting is applied for this purpose. Desalting involves mixing the crude oil with water at a temperature of about 250°F (121.1°C) under enough pressure to prevent evaporation of both water and volatile crude oil components. The salts are dissolved and removed by the water. Oil/water emulsions often form which also contain salts. The emulsions can be broken by the use of high-voltage electrostatic coalescers or by the use of demulsifying chemicals. 

Removal of naphtha and distillate fractions from the crude oil under atmospheric pressure distillation requires charge temperatures to be maintained below the cracking temperature of the crude oil components. This temperature will vary but can typically range from 750°F to 800°F (398.9°C to 426.7°C). Occasionally, even lower temperatures may be required. Above these temperatures, crude oil components can begin to thermally crack and foul processing equipment. 

A variety of non-hydrocarbon species is found in crude oil. These compounds are found in all molecular weight ranges of crude oil components, but seem to concentrate in the heavier distillate and residual oil fractions. The effect of these materials on processing equipment, refining catalysts, and finished product quality can be dramatic. Corrosion, catalyst poisoning, and fuel stability problems can all be due to the effect of these nonhydrocarbon species. 

The effect of retrograde condensation on a crude oil component such as octane is particularly significant, and small amounts of these heavier components if left in the gas also have a great effect an hydrocarbon dewpoints. Even with extensive gas conditioning cooling it is difficult to remove all crude oil ccanpcnenta from the vapor streams at a pressure of 1500 psl. Note that the K-value for octane at 0°F and 1500 psi is not as low as at 100°F and 1000 psi. 

The boiling point is the last data herein sought out however, it is indeed the most important data to secure for a discrete pure component or a pseudo-crude cut component. Since the discrete pure components are generally a known type of molecular structure, their boiling points may readily be obtained or estimated from data sets such as Table 1.3. The crude oil components are left, unfortunately, undefined. Therefore, this section is dedicated to defining the boiling points of crude oil and its products. 

In most cases, the temperature and pressure of application exceed the critical values for carbon dioxide, but the temperature is lower than the average critical temperature and above the average critical pressure of the crude oil components. Hence, under conditions of use the carbon dioxide is a fairly dense fluid which is neither a liquid or a gas, but the crude oil is a liquid. There is also salty water present in the oil reservoir in all cases, and water is used to drive a slug of carbon dioxide through the reservoir from injection to production wells which are typicAlly arranged in five-spot or nine-spot patterns. 

While alkylfluorenes are abundant and persistent crude oil components... 

The composition of crude and refined oils is quite complex and covers a broad spectrum of organic compounds. It is not uncommon to find in it compounds ranging from very volatile, low-molecular-weight hydrocarbons to nonvolatile tarry residues composed of very complex polynuclear aromatic hydrocarbons. Some of the crude oil components (hydrocarbons) are essentially not soluble in water, while others (phe-... 

Despite the natural mitigation of some of the effects of adverse mobility ratio, most of the C02 floods that have been performed in the field, and in large core samples in the laboratory, are distinguished by early C02 breakthrough and lower displacement efficiency than expected. Thus, C02 floods do suffer from both the adverse mobility ratio and from this solvent s incomplete miscibility with all crude oil components. 

The determination of EACN is based on the minimum interfacial tension derived from a test siufactant in a series of hydrocarbon solvents, and then in the crude oil. The alkane carbon numbers are assigned to the solvent. In its determination for the crude oil/component, the minimum interfacial tension (IFT) against the reference surfactant may match one of the reference hydrocarbon solvent. The n-alkane with this minimum would be the EACN for the crude. The demulsifiers are tested in a similar way to the surfactants and are assigned preferred alkane carbon numbers (PACN) in the crude. This appeared to be a way of predicting their behavior in crude oils from their behavior in the n-alkanes. However, this process is long and labor intensive. 

M-H Ese. Langmuir film properties of indigenous crude oil components influence of demulsifiers, PhD thesis. University of Bergen, 1999. 

The film properties of some selected Chinese and North Sea crade oils are the topics of the next two chapters, by Li, Peng, Zheng, and Wu and by Yang, Lu, Ese, and Sjoblom. Different aspects of interfacial rheology (interfacial shear viscosity) and Langmuir films are explored in depth for the crude oils as such or, alternatively, for selected crude oil components. Correlations between these findings and the macroscopic emulsion stability are pointed out. 

Table 1 Geometry parameters of PP fibers and their separation efficiency for crude oil components from waste water [DIN 38409 STN 83052]...

A sensitive method for the estimation of different surface active compounds (tetraalkylammonium salts, dextrans, crude oil components) in water is based on the measurements of the depression of the electrocapillary curve under conditions where the transport of the compound to the dropping Hg-electrode is accelerated by stirring of the solution being examined[12] The detection limit is in the range of 10-100 jjg 1 More details on "adsorptive polarographic analysis" are given in[13]. 

The recommended physical and chemical analyses for determination of the general characteristics of a crude oil are given in Tables 4 and 5. Results of these analyses provide a solid basis for comparison of crude oils from different formations and fields. The crude oil components that have the greatest potential effect on corrosion are the polar organic... 

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