Composition Crude Oil

Understanding the factors that inhibit the foaming power is of great importance, because it yields a basic knowledge— how the materials produced will perform with respect to foaming. It also serves to predict how individual crude oil compositions would work with different defoamers [301]. 

In a petroleum refinery a large number of different products are produced, and the demand for some of these products is seasonal. For instance, there is not much need for residential fuel oil in the summer. The price of products also varies from day to day. To optimize the company s profit, it is therefore necessary periodically to vary the amount of each product produced. This can be done by changing the amounts of material sent to cracking units and reformers and by changing the conditions in these and other process steps. Some petroleum companies provide a computer with the data on market prices, current inventories, and crude oil compositions. The computer output then specifies the operating conditions that will yield the greatest profit for the company. The computer could then make the changes in these conditions directly, or this could be done manually. 

The objective of this work is to study the possible influence of the crude oil composition on the amount of coke deposit and on its ability to undergo in-situ combustion. Thus, the results would provide valuable information not only for numerical simulation of in-situ combustion but also to define better its field of application. With this aim, five crude oils with different compositions were used in specific laboratory tests that were carried out to characterize the evolution of the crude oil composition. During tests carried out in a porous medium representative of a reservoir rock, air injection was stopped to interrupt the reactions. A preliminary investigation has been described previously (8). 

Crude Oils. Part a of Table I compares branched alkanes observed in Fischer-Tropsch products with those observed in a representative crude oil. Part b predicts Fischer-Tropsch product along with the relative concentrations of isomers in terms of a and /, and part c predicts crude oil compositions. In this last portion of Table I comparisons are given for branched isomers for / = 0.176. The comparison of observed and predicted normal Ce and C is not very similar with f = 0.176 however, as noted in the footnote, a change of / value to 0.1 produces a very close comparison for the normal compounds. 

Milton Denekas. The implication of the relation of crude oil composition to a Fischer-Tropsch product is that oil has been produced by a synthetic process (building-up) rather than by a degradative process. Can you assume that the products from coal pyrolysis are also produced by a synthetic building-up) process rather than by degradation ... 

These results imply that since residual crude oil composition changes as it undergoes extraction by injected COj, the optimum COj mobility control agent may change during the course of the COj flood. 

Powell T. G. and McKirdy D. M. (1973) Relationship between ratio of pristane to phytane, crude oil composition and geological environment in Australia. Nature 243, 37-39. 

When everything is put together, the simulation of a trickle bed reactor with aging requires a very fast computer of the Cray class. [17] The advantage of nonuniform activation of the catalyst in the radial direction was investigated, and a center-loaded catalyst can extend the catalyst life by 30% in comparison with a uniform catalyst with the same overall activity. [17, IS] The precise optimum condition is sensitive to the parameters values of the crude oil composition, catalyst support and operating conditions. 

The enrichment (or the pressure) needed to develop miscibility between the injectant and the oil is determined experimentally in one-dimensional slim-tube tests.As the enrichment (or pressure) increases, the slim-tube recovery reaches a plateau long before first contact miscibility is developed. This enrichment is called the minimum miscibility enrichment, or MME, which is a function of reservoir pressure, temperature, and contaminants in the solvent. Similarly, a pressure called the minimum miscibility pressure, or MMP, can be identified for any solvent. Other experimental methods (e.g., rising bubble method) are also available to determine MMP or MME. In vaporizing three component systems, MMP (or MME) corresponds to the pressure (or enrichment) at which the critical tie line passes through the crude oil composition. In condensing three component systems, MMP (or MME) corresponds to the pressure (or enrichment) at which the critical tie line passes through the solvent composition. ... 

Based on this concept, a crude oil/surfactant/brine system should have phase behavior (e.g., optimum salinity, IFT minima) similar to that of the pure alkane/ surfactant/brine system whose ACN is the same as the crude EACN. However, the concept of EACN is not practically applicable for several reasons. First, all the hydrocarbon compositions of a crade oil are not readily identified. Thus, the EACN of a crude oil cannot be calculated directly using Eq. 7.79. Second, measurement of the EACN of a crude oil requires a series of surfactant solutions to be tested to obtain individual minimum ITT. Then these surfactant solutions are tested against increasing alkane carbon numbers to find minimum IFTs. The ACN at which a surfactant solution also gives the lowest IFT for the crude oil is the EACN of the oil. Finding it is not an easy task. Third, several parameters affect the value of the EACN. Variations in EACN with alcohol cosolvent type, total WOR of the sample, and crude oil composition have been observed (Tham and Lorenz, 1981). In practice, we always select surfactants by scan tests using the actual crude oil for a specific application. 

In aLkaline flooding, the injected aUcali reacts with the saponifiable components in the reservoir crude oil. These saponifiable components are described as petroleum acids (naphthenic acids). Naphthenic acid is the name for an unspecific mixture of several cyclopentyl and cyclohexyl carboxylic acids with molecular weight of 120 to well over 700. The main fractions are carboxylic acids (Shuler et al., 1989). Other fractions conld be carboxyphenols (Seifert, 1975), porphyrins (Dnnning et al., 1953), and asphaltene (Pasquarelli and Wasan, 1979). The naphtha fraction of the crnde oil raffination is oxidized and yields naphthenic acid. The composition differs with the crude oil composition and the conditions dnring raffination and oxidation (Rndzinski et al., 2002). 

There are, however, some general relationships of crude oil composition that can be derived from pour point and viscosity data. Commonly, the lower the pour point of a crude oil the more aromatic it is, and the higher the pour point the more paraffinic it is. 

Smith, H. M., Qualitative and Quantitative Aspects of Crude Oil Composition . Bureau of Mines, Bartesville (1968). 

Crude oil compositions vary widely. Depending on the sources of carbon from which the oils are generated and the geologic environment in which they migrated and from which reservoir, they can have (1) dramatically varied compositions in the C5 to C42 carbon range such as relative amounts of paraffinic, aromatic and asphaltenic compounds (2) large differences in the w-aUcane and cyclic-aUcanes (such as aUcyl cyclo-hexanes) concentrations and distribution patterns and UCM profiles ... 

Palmer, S. E. 1993. Effect of biodegradation and water washing on crude oil composition. In Engel... 

Palmer, S. E. 1993. Effect of biodegradation and water washing on crude oil composition. In Engel, M. J. Macro, S. A. (eds) Organic Geochemistry Principles and Applications. Plenum Press, New York, 511-533. 

Nonetheless, fliere was still the option of activating the natural surfactants (231, 232) that are a part of the heavy crude oil composition (probably resins and asphaltenes). This is a well-known technology in enhanced oil recovery (233-236), in which a strong base, e.g., sodium hydroxide, is used to activate flie carboxylic acids that are contained in the crude oil (237-240). 

In this study, experimental data on the amount of asphalt and asphaltene precipitation due to addition of solvents to West Sak crude were gathered. The first set of tests were conducted for West Sak stock tank oil. Solvents used include ethane, carbon dioxide, propane, n-butane, n-pentane, n-heptane, Prudhoe Bay natural gas (PBG) and natural gas liquids (NGL). Effect of solvent to oil dilution ratio on the amount of precipitation was studied. Alteration of crude oil composition due to asphalt precipitation was measured using gas-liquid... 

Lafargue, E., Barker, C. (1988) Effect of water washing on crude oil composition. American Association of Petroleum Geologists Bulletin, 72,263—276. 

These observations of Callaghan et al. [3] imply that crude oil compositional differences can significantly influence antifoam effectiveness in the case of PDMS oils. It is possible, for example, that degassing a crude oil will remove the lower hydrocarbon components to decrease the solubility of the antifoam and enhance effectiveness. Antifoams that are effective in degassed dead crude oils may therefore be ineffective in live crude oils. Thus, Callaghan et al. [3] cite an example where both a PDMS oil and an ethoxylated PDMS were effective in degassed crude oil but only the ethoxylated PDMS was effective as an antifoam in the live crude oil, presumably as a consequence of lower solubility. 

Disturbance variables (DVs) Process variables that affect the controlled variables but cannot be manipulated. Disturbances generally are related to changes in the operating environment of the process for example, its feed conditions or ambient temperature. Some disturbance variables can be measured on-line, but many cannot such as the crude oil composition for Process (c), a thermal cracking furnace. 

A series of articles [4-9] illustrate the diversity of crude oil assay practices employed by major refiners in the United States and Austria. The dissimilarity of results reported in the literature [10 ] is a reflection of this independent development of analytical schemes, even though standardized approaches to crude oil analysis have previously been published 11,12 ]. Despite the complexity of crude oil composition and the diversity of analytical methodology, probably more crude oil analyses are routinely performed on a daily basis using inher-... 

Pour point and viscosity determinations of crude oils are performed principally to ascertain their handling characteristics at low temperatures. There are, however, some general relationships about crude oil composition that can be derived from pour point and viscosity data. Commonly, the lower the pour point of a crude oil the more aromatic it is, and the higher the pour point, the more paraffinic it is. There are numerous exceptions to this rule-of-thumb, and other data must be used to verify a crude oil s character. Probably the most widely used index is the Characterization or K Factor [75 ], which was originally defined as the cube root of the average molal boiling point in °F absolute (Rankine) tempera-... 

---