Characterization and Classification of Some Egyptian Petroleum Crude Waxes Using Different Techniques

Abstract

In order to characterize and identify some crude waxes, derived from various Egyptian petroleum distillates and residues, suitable for production of different types of petroleum waxes, many standard test procedures have been used for measurement the physical characteristics of crude waxes and wax products. Moreover, some analytical techniques such as gas chromatography (GC), Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (H-NMR), urea adducting analysis, and solid-liquid chromatography have been used to characterize the crude waxes. Finally, one stage fractional crystallization has been done to separate the hard waxes from El-Ameria and Suez heavy slack waxes and Alexandria and Suez crude petrolatums using ethyl acetate solvent at an ambient temperature of 20^○C and at fixed dilution and washing solvent ratios of 7:1 and 6:1 by weight, respectively. The resulting wax products are evaluated according to TAPPI-ASTM equation and petroleum wax specifications.     

Prediction of the Kinematic Viscosity of Crude Oil Fractions

Abstract

A generalized equation based on modified Eyring's theory for predicting kinematic viscosity of petroleum fractions is proposed in this work. The equation uses two reference fluids including a pair of (C6 and C10), (C10 and C14), or (C14 and C20) for petroleum fractions of molecular weight higher than 70 and lower than 300.

Validity and accuracy of this equation have been confirmed by comparing the obtained results of this equation with experimental data. In contrast to other correlations that require so many specific parameters for oil viscosity prediction, this type of equation requires only molecular weight and true boiling point. The results obtained in this work are in agreement with experimental data with an average absolute deviation (AAD) of less than 5%.     

A Simple Method for Oil Content Determination of Petroleum Waxes by Refractive Index Measurement

The oil content of petroleum wax is an important parameter for evaluating the quality of petroleum waxes. In order to characterize petroleum waxes, the relation between the oil content of waxes and their refractive index is investigated. Sixteen groups of waxes with different amounts of oil content are separated from a special raffinate using crystallization technique with MEK and toluene solvents. A direct measurement of the wax refractive index replaces the oil content evaluation method of petroleum wax. Refractive index is readily measured and is a good indicator of the oil content of petroleum waxes. The results show a linear relation between the oil content of the studied waxes and their refractive indexes.     

Modeling the heat of vaporization of petroleum fractions and pure hydrocarbons

The present contribution was aimed to estimate the vaporization enthalpy of petroleum fractions and pure hydrocarbons by using the combination of adaptive neuro-fuzzy inference system (ANFIS) and genetic algorithm (GA) called GA-ANFIS. This tool can approximate the vaporization enthalpy as a function of the specific gravity, molecular weight, and boiling point temperature with high accuracy based on 122 data gathered from the previously published literature. Furthermore, results from the proposed model have been compared with different correlations and its acceptable predictive ability against other correlations was proved in order to the estimation of the vaporization enthalpy. The percentage of absolute relative deviation and R-squared (R²) was 1.64% and 0.9967%, respectively. This tool is simple to use and can be of considerable help for petroleum engineers to have an accurate estimation of vaporization enthalpy of hydrocarbon fractions of pure hydrocarbons.     

Modeling of wax deposition produced in the pipelines using PSO-ANFIS approach

Wax deposition in petroleum industry is one of the major problems requiring accurate predictive procedures to reduce the deficiencies and effective designing of the process. An adaptive neuro fuzzy inference system (ANFIS) model is proposed to predict the wax deposition in oily systems. Parameters of the ANFIS model are optimized using the particle swarm optimization (PSO) method. Results are then compared to those previously reported by Kamari et al., demonstrating better performance of the proposed ANFIS model. Statistical and graphical approaches are employed to investigate the reliability of the proposed model, illustrating the model's capability of precise estimation of the wax deposition. Coefficient of determination (R²) and mean squared error (MSE) values of 0.994 and 0.053 are obtained for the proposed ANFIS model, revealing the reliable prediction of wax deposition by the proposed ANFIS model.     

Applying Grid partitioning based Fuzzy inference system method to estimate interfacial tension of brine and hydrocarbon

The oil recovery reservoirs and oil trapping in the reservoirs are extensively function of interfacial tension between brine and hydrocarbon, so estimation of interfacial tension becomes one of the interesting topics in petroleum industry. In this study, Grid partitioning based Fuzzy inference system method is utilized to forecast interfacial tension of hydrocarbon and brine based on various effective parameters such as ionic strength of brine, carbon number of hydrocarbon, pressure, and temperature. The estimated values of interfacial tension were compared with real interfacial tension of brine and hydrocarbon using graphical and statistical analyses. The determined coefficients of determination (R²) for training and testing phases were 0.9916 and 0.9447, respectively. The comparing analyses express that the Grid partitioning based Fuzzy inference system method has great ability in prediction of interfacial tension, and it can be used as an applicable tool in petroleum industry.     

Effect of temperature and concentration of solutions on the position of <Superscript>13</Superscript>C NMR signals for fractions of saturated hydrocarbons forming urea adducts

An empirical equation was proposed for calculating the chemical shifts of ¹³C NMR signals from monomethylated alkanes and mono-n-alkyl-substituted cyclopentanes and cyclohexanes in the spectra of isoparaffin and naphthene fractions that form adducts with urea, depending on the analyte concentration in deuterochloroform C and the spectrum recording temperature T _rec. Deviations of the calculated chemical shifts from the measured values did not exceed 5 × 10^?3 ppm while varying T _rec from 303 to 323 K and C from 200 to 600 mg/ml. It was shown that such an accuracy is sufficient for the unequivocal identification of components by means of ¹³C NMR technique; ignoring this dependence leads to errors in signal assignment in the spectra of petroleum fractions. The use of the chemical shift of certain signals as internal standards for determination of T _rec and C was proposed. It was assumed that numerical values of the temperature and concentration coefficients that describe the dependence of the chemical shift on T _rec and C would be useful for the ¹³C NMR detection of new groups of compounds in petroleum hydrocarbons.     

Estimating Methyl/Methylene Groups in Asphaltene and Other Fractions of Asphalt

Abstract

Infrared is the most widely used analytical method for interpreting the structure of petroleum fractions. In this study, IR spectra of standard normal nonadecane were used to get ε for methyl and methylene groups. A linear relationship was obtained by plotting the peak intensities at 2,954, 2,926, 2,854, 1,466, and 1,376 cm^?1 against different amounts of N-nonadecane. The R ² obtained for most of the plots was in the range of 0.988–0.997. The Beer-Lambert's law was used for the first time to quantitatively estimate the weight percent of methylene and methyl groups present in the different fractions of asphalt.     

The Kinetics of Catalytic Oxidation of 1-Butanethiol in a Gas Liquid System

Abstract

In the present study the kinetics of liquid phase oxidation of light thiols using reformulated cobalt phthalocyanine based catalyst has been investigated in a semi batch bubble column reactor. 1-Butanethiol is chosen to represent thiols in lighter range of petroleum fractions like liquefied petroleum gas and light straight run naphtha. The study has shown that rate of catalytic oxidation of 1-butanethiol is linear at lower concentrations and of nonlinear nature at higher concentrations. A mechanism based rate expression has been obtained to explain this behavior and its parameters are estimated. The derived rate law is similar to Michaelis-Menten rate equation.     

The Structural Characterization of Saturate,Aromatic, Resin,and Asphaltene Fractions of Batiraman Crude Oil

Abstract

The structural characterization of fractions of Batiraman crude oil, which is the heavy crude oil from a field in the southeastern part of Turkey, was investigated. Batiraman crude oil and its saturate, aromatic, resin, and asphaltene (SARA) fractions were seperated. Treatment of crude oil with n-heptane provided the separation of asphaltene. Maltene was collected by evaporating the n-heptane from the filtrate. Then, maltene was separeted into saturates, aromatics, and resins by SARA technique. Maltene was separated into saturate, aromatic, and resin fractions using column chromatography. SARA fractions were quantified on a weight percent basis. Fractions of Batiraman crude oil were characterized by elemental analysis, proton nuclear magnetic resonance (¹H NMR) analysis, electrospray ionization mass spectrometry (ESI-MS), and Fourier transform infrared (FTIR) spectroscopy techniques.     

Computational aids for the estimation of the molecular weight of petroleum oils from kinematic viscosity measurements

The ASTM standard D 2502-92 (reapproved 2004) provides a means of calculating the mean molecular weight (relative molecular mass) of petroleum oils from kinematic viscosity measurements. It is applicable to samples with molecular weights in the range from 250 to 700 g/mol and is intended for use with average petroleum fractions. Nevertheless, this estimation was carried out by using a viscosity-molecular weight chart that involves evident interpolation errors. In this work, we have used both of Hirschler’s equations as numerical methods in order to carry out an analytical estimation of the mean molecular weight of petroleum oils from kinematic viscosity measurements. The data provided by the named Hirschler-Maroto equation are in excellent agreement with the ASTM chart for a viscosity index range that covers the majority of commercial oils. Finally, by using the Hirschler-Maroto equation we have designed a PC program in order to make the evaluation of molecular weight of petroleum oils easier for engineers and professionals. The use of this program, which can be downloaded free from the Internet, only requires the insertion of kinematic viscosity data, which remove any graphical or interpolation errors. Nevertheless, the Hirschler-Maroto equation and the PC program must be cautiously used in order to avoid important errors when applied to the higher molecular weight constituents of petroleum. Published in Russian in Neftekhimiya, 2007, Vol. 47, No. 2, pp. 103–107. The text was submitted by the authors in English.     

Microbial treatment of waxy crude oil for mitigating wax precipitation and improving liquidity

The wax deposition of crude oil during transportation reduces the inner diameter, blocks the pipeline, and eventually increases the cost of petroleum production. This study reports a paraffin-degrading bacterial strain DG2 isolated from petroleum-contaminated soil. The effect of this strain on the removal of paraffin in crude oil was investigated. DG2, identified as Pseudomonas, produced biosurfactant that reduced the surface tension to 35.7?mN/m^?1 and exhibited high emulsification activity. Results of gas chromatography–mass spectrometry analysis of the waxy crude oil treated by DG2 showed decreased heavy hydrocarbon fractions (C25 and C32). The degradation test revealed that DG2 reduced the wax appearance temperature by 4.16?°C and the viscosity by 23% of the waxy crude oil. These findings indicate that paraffin-degradation strain DG2 may be used for effective paraffin biodegradation.     

Effect of Severity on Hydrotreating of Demetallized Oil Monitored by 1H-NMR Spectroscopy

Abstract

A study on aromatic hydrogenation of demetallized oil has been carried out using a commercial catalyst under pilot plant reaction conditions similar to those found in industrial processes. The feedstock was contacted with the catalysts in a trickled bed reactor unit at 330°C, 350°C, and 370°C. A combination of physicochemical characterization of feed and products and ¹H-NMR spectra was used to monitor changes in the aromatic fractions caused by variation in reaction temperature. Analysis of the ¹H-NMR spectra, along with the quantitative variation in the areas of the resonance lines, showed that the diaromatics with relatively long alkyl changes present in the lightest distillation cuts of the products were highly hydrogenated. In contrast, smaller changes in aromaticity in the heaviest fractions were observed under the same conditions. A limit of about 2 wt% of the integrals corresponding to the diaromatic+ species suggests a thermodynamical limitation of hydrogenation under the studied reaction conditions.     

KINEMATIC VISCOSITY-TEMPERATURE CORRELATION FOR UNDEFINED PETROLEUM FRACTION OF A WIDE BOILING RANGE

A new correlation was developed to predict the effect of temperature on Kinematic Viscosity of petroleum fractions of all boiling ranges including 455^?°C. This correlation covers a wide boiling ranges of petroleum fractions. This correlation has been developed to represent the data for a wide range of temperature from 30 to 200°C. The correlation is based on experimental kinematic viscosity data for twenty TBP fractions of Arab heavy, Arab medium and Arab light and Arab extra-light crude oils. The proposed correlation has been found to fit all the experimental data consisting of 248 measurements of the kinematic viscosity with an over all average absolute deviation of 7.2% compared to 9.1% given by Amin (1994) et al. method.     

Application of MLP-ANN as novel tool for estimation of effect of inhibitors on asphaltene precipitation reduction

Sedimentation of heavy fractions of oil such as asphaltene is the main concern in different parts of petroleum industries like production and transportation. Due to this fact, the inhibition of asphaltene precipitation becomes one of the great interests in the petroleum industry. In the present investigation, multi-layer perceptron artificial neural network (MLP-ANN) was developed to estimate asphaltene precipitation reduction as a function of concentration and kind of inhibitors and oil properties. To this end, a total number of 75 data points were extracted from reliable source for training and validation of predicting algorithm. The outputs of MLP-ANN were compared with experimental data graphically and statistically, the determined coefficients of determination (R²) for training and testing are 0.996522 and 0.995239 respectively. These comparisons expressed the high quality of this algorithm in the prediction of asphaltene precipitation reduction. so the MLP-ANN can be used as a powerful machine for estimation of different processes in petroleum industries.     

Methods of Analysis of High-Wax Crude Oils. Resins,Asphaltenes, Paraffin Waxes

Methods of determining the content of resins, asphaltenes, and paraffin waxes and distillation of the waxes applied to high-wax crudes are reported. The method is based on the experience from many years of research on ozocerites, minerals of petroleum origin that primarily consist of paraffin waxes, and crudes with a high wax content.__________Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 3, pp. 48 –50, May – June, 2005.     

Group composition and properties of petroleum wax fractions

The group chemical composition and physicomechanical properties of petroleum wax fractions are investigated. The mechanism of their change with an increase in the average distillation temperature is determined.Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 1, pp. 47 – 48, January – February, 2005.     

Composition and Properties of Some Petroleum Waxes

Abstract

Structural composition of paraffin waxes and soft wax fraction derived from microcrystalline wax were determined. Waxes were fractionated by multistage solvent crystallization at different temperatures. The n-alkane components of the waxes were separated by urea adduction. The average structural parameters of parent waxes, their fractions, and urea adductables were estimated by ¹h and ¹³C NMR spectroscopy. The thermal parameters viz. phase transition temperature and the associated energy during phase transitions were determined by using DSC and correlated with the penetration temperature behavior of waxes. The carbon number distribution determined by GC for these waxes and their n-alkane components were also correlated with physical properties and thermal parameters.     

A Process for the Preparation of Emulsified Wax

Abstract

With the use of petroleum wax and oxidized petroleum wax as raw material and by appraising and screening emulsifier, the effects on stability of emulsifying wax such as emulsifier type, quantity, stirring speed, emulsifying time, and emulsifying temperature are discussed. The experiment results show that the mass ratio of petroleum wax and oxidized petroleum wax is 15–25%; the mass ratio of mixed emulsifier CC is 7–8%; and the best emulsifying process conditions are an emulsifying temperature of 90°C, an emulsifying time of 40 min, and a stirring speed of 700–1000 r/min. The emulsified wax obtained subsequently has better stability, dispersivity, and property.