Roman M. Balabin

Capabilities of near infrared spectroscopy for the determination of petroleum macromolecule content in aromatic solutions

In this paper the application of near infrared (NIR) spectroscopy for the determination of petroleum macromolecules content in model systems is reported. Eighty (80) solutions of three main types of oil macromolecules (asphaltenes, resins, and paraffins) in toluene were studied. NIR spectra within the range 8,000–14,000 cm−1 were used to construct calibration models using the partial least squares method. The low prediction error of the models (0.43, 0.79 and 0.39% w/w for asphaltenes, resins and paraffins, respectively) indicate that NIR spectroscopy can be applied to analyse the petroleum macromolecule content in natural systems (crude oil and its refined products).

Frequency Dependence of Oil Conductivity at High Pressure

Electric conductivity of materials is defined by a competition of several mechanisms of charge carrier movement: phoretic, ionic and electron‐hole jumping. The relative contribution of them is not constant when thermodynamic conditions are changing. Paraffine and naphtene hydrocarbons are typical dielectrics. Formation of supermolecular structures is accompanied by ordering of asphaltene‐resin and polyaromatic molecules. Solvate shells contain the molecules with less molecular masses. The disperse particle from the centre to periphery is characterized by reduction of conductivity from the values peculiar to “good” semiconductors in a nucleus, “average” in intermediate phase to typical for dielectrics in the disperse media. Threshold of the mobility of charge carriers is determined by temperature, pressure, strength of the external field, width of the forbidden zone, and nature of components of the disperse media and phase. Spectra of conductivity of model asphaltene solutions and Kumkolskaya oil in frequency range from 10−3 up to 106 Hz are measured for pressures up to 1 GPa in temperature interval from 250 to 320 K. Particularly at the analysis of spectra of conductivity the technique offered by Sheu and Mullins is used. Dependences were approximated by power‐law functions according to the concept of Jonschers “the universal response.” Influence of pressure and temperature to the exponents is analyzed. Values of activation energy are determined. Received data can be useful for prognosis of oil phase behavior at high pressures.

Polarization of Fluorescence of Asphaltene Containing Systems

Formation of supermolecular structures in petroleum disperse systems is determined by interactions of asphaltenes. Petroleum systems are lyophilic oleocolloids with low polar dispersive media which is in dynamic balance with elements of disperse structure. Supermolecular scale of organization is most important for determining the macroscopic parameters. Levshin-Perrin equation for depolarization of fluorescence was modified for polydispersed systems. Interfacial tension coefficient of model asphaltene solution was calculated in a case of Volmers function. For technogenic mixtures the temperature dependences of the sizes near the point of phase transition are presented. Enthalpy of asphaltene association per one molecule was calculated. Polarization degree together with macroscopic parameters correlates with appearance of asphaltene dispersed phase in system.

Universal technique for optimization of neural network training parameters: gasoline near infrared data example

The universal technique of finding optimum training parameters for multi-layer perceptron—such as percentage of samples in a cross-validation set and quantities of training iterations with various initial values—is offered. This technique is aimed at the searching of optimum values of two complex factors depending on accuracy and convergence of a network, and also on the time of its training. Their conventional names are “cross-validation coefficient” and “training iteration coefficient”. Near infrared spectroscopy data for gasoline samples are used to evaluate the efficiency of the method.

Dispersed Structure of Ethanol‐Gasoline Fuel According to Dynamic Light Scattering Method

The dispersed structures of mixtures of five different gasolines with anhydrous ethanol were investigated by the dynamic light scattering (DLS) method. The aim of the work was to find whether these blends are colloid systems. Influence of different parameters was investigated to verify the results of this research. Ethanol‐gasoline blends were found to be colloid systems with the drop size of 20–150 nm.