Crude oil evaluation

All in all, the petroleum industry has invested considerable effort in developing sophisticated mathematical programming models to help planners provide overall planning schemes for refinery operations, crude oil evaluation, and other related tasks. 

Specific crude oil evaluations have been successfully performed by the use of the system. Other applications are being developed and will be tried shortly. Although we have just started to use the system, the following points have been established ... 

Initially, uses of the TOLPREP system have centered on crude oil evaluation. Here is a specific example of such an evaluation ... 

A method has been developed to predict the amount of slurry oil plus coke that will be obtained from a given reduced crude in Ashland s RCC process under various operational efficiencies by knowing the molecular type composition of the reduced crude. This method is currently being used in Ashland s crude oil evaluation program. At the present time Ashland s commercial RCC unit is operational and adjustments are being made to the prediction equation in order to predict yields from the commercial unit. Work on developing equations to predict the yield of other RCC products continues. 

Several references have suggested the need for alternative crude oil evaluation methods. These alternative methods (both analytical and mathematical) should allow keeping the assay information updated under a reasonable cost. 

The center of this technology is an expert system for crude assay generation. This expert system, which includes a set of mathematical algorithms based in powerful data-mining techniques and first-principle models, may generate a complete crude oil evaluation from variable levels of information available. 

Linear programming involves the maximization of a linear objective function of many variables subject to linear constraints on each variable [57]. In the context of a refinery, the objective function can refer to the overall profit generated from processing a particular set of crudes. The variables that affect this objective function are typically the amounts of different crudes purchased. The goal is to determine an optimal set of crudes that maximize the profit margin of the refinery. This scenario is an example of crude oil evaluation. Refiners typically use LP methods... 

Although distillation and elemental analysis of the fractions provide a good evaluation of the qualities of a crude oil, they are nevertheless insufficient. Indeed, the numerous uses of petroleum demand a detailed molecular analysis. This is true for all distillation fractions, certain crude oils being valued essentially for their light fractions used in motor fuels, others because they make quality lubricating oils and still others because they make excellent base stocks for paving asphalt. 

The methods for the evaluation of crude oils are examined in Chapter 8. 

Practically, one measures the quantity of total sulfur (in all its forms) contained in crude oil by analyzing the quantity of SO2 formed by the combustion of a sample of crude, and the result is taken into account when evaluating the crude oil price. When they are present, elementary sulfur and dissolved H2S can also be analyzed. 

H. Shaw, C. D. Kalfadehs, and C. E. Jahnig, Evaluation of Methods to Produce Aviation Turbine Fuels From Synthetic Crude Oils-Phase I, Technical Report AFAPL-TR-75-10, Vol. 1, Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio, Mar. 1975. 

Water-in-oil macroemulsions have been proposed as a method for producing viscous drive fluids that can maintain effective mobility control while displacing moderately viscous oils. For example, the use of water-in-oil and oil-in-water macroemulsions have been evaluated as drive fluids to improve oil recovery of viscous oils. Such emulsions have been created by addition of sodium hydroxide to acidic crude oils from Canada and Venezuela. In this study, the emulsions were stabilized by soap films created by saponification of acidic hydrocarbon components in the crude oil by sodium hydroxide. These soap films reduced the oil/water interfacial tension, acting as surfactants to stabilize the water-in-oil emulsion. It is well known, therefore, that the stability of such emulsions substantially depends on the use of sodium hydroxide (i.e., caustic) for producing a soap film to reduce the oil/water interfacial tension. 

Corexit 9527 is a water-and ethylene glycol monobutyl ether-dissolved dispersant. The nature of the surface-active agent has not been disclosed. Laboratory tests were conducted using 0.5-mm thick, fresh Alberta Sweet-Mixed Blend crude oil treated with Corexit 9527 dispersant applied from an overhead spray boom [165]. The effects on dispersion efficiency of mixing jet pressure, mixing jet flow rate, jet standoff distance, and vessel speed were evaluated. The system operates with a nozzle pressure of 7000 kPa, a flow rate of 55 liter/min per nozzle, and nozzles positioned approximately 0.6 m from the water surface. In laboratory tests, such a system was capable of dispersing 80% to 100% of the surface slick. 

The effectiveness of a number of crude oil dispersants, measured using a variety of evaluation procedures, indicates that temperature effects result from changing viscosity, dispersants are most effective at a salinity of approximately 40 ppt (parts per thousand), and concentration of dispersant is critical to effectiveness. The mixing time has little effect on performance, and a calibration procedure for laboratory dispersant effectiveness must include contact with water in a manner analogous to the extraction procedure otherwise, effectiveness may be inflated [587]. Compensation for the coloration produced by the dispersant alone is important only for some dispersants. 

The current research objective is to evaluate the surface activity of the subfractions obtained from the solvent fractionated crude oil and shale oil samples as they are passed through the separation process developed for this work. The columns used are anion exchange resin,... 

DEMULSIFICATION TESTS. Demulsification tests were conducted using standard bottle test procedures to evaluate the relative performance of Thin Film Spreading Agents in coalescing emulsions of formation brine in crude oil under reservoir conditions. 

Thus, initial inspection of the nature of the petroleum will provide deductions about the most logical means of cleanup and any subsequent enviromnental effects. Indeed, careful evaluation of petroleum from physical property data is a major part of the initial study of any petroleum that has been released to the enviromnent. Proper interpretation of the data resulting from the inspection of crude oil requires an understanding of their significance. Consequently, various standards organizations, such as the American Society for Testing and Materials (ASTM, 2004) in North America and the Institute of Petroleum in the United Kingdom (IP, 2004), have devoted considerable time and effort to the correlation... 

An important step in assessing the effects of petroleum products that have been released into the environment is to evaluate the nature of the particular mixture and eventnally, select an optimum remediation technology for that mixture. As a general rule, crude oil (unrefined petroleum) is a complex mixture composed of the same compounds, but the quantities of the individual compounds differ in crude oils from different locations. This rule of thumb implies that the quantities of some componnds can be zero in a given mixture of compounds that comprise crnde oil from a specific location. 

The fate of four petroleum mixtures has been evaluated using three approaches—evaluating the fate of (1) indicator chemicals, (2) the mixture of the whole with a surrogate, and (3) the hydrocarbon mixture as a whole. The four mixtures were crude oil, JP-5, mineral spirits, and diesel. The choice of approach requires the consideration of availability and quality of data on the mixture, the mobility and toxicity of the mixture, and the availability of site data (Custance et al. 1992). 

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