Rustem Z. Syunyaev

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.

The influence of the internal structure and dispersity to structural–mechanical properties of oil systems

Abstract Some oils and oil products are dispersed systems with composite internal organization. The dynamical model of dispersed particle, named complex structural unit (CSU), with complicated internal structure is suggested. A nucleus surrounded by solvate shell contains high-molecular mass components of different natures. Sizes of nuclei and solvate shells change in accordance with the magnitude of external influence. An optimal correlation between parameters of CSU and the value of external factor can be fixed for every technological process. The results of determination of the dispersity degree in oil systems are presented. Connection of nonmonotonous extremal dependence macroscopic parameters (viscosity, stability, etc.) and microscopic ones (particle sizes) with external influence value changing is shown. These regularities are basic for the intensification of technological processes. Technology is tested in practice with good results. For managing structural–mechanical properties, the addition of heavy residue, containing significant amount of resin–asphaltene substances (RAS), has been chosen together with thermal treatment and regulation of speed of cooling. Speed of cooling determines sizes and number of interacting particles. Connections between particles could be realized through the solvate shells formed from RAS or directly with each other. Finally, the structure of coalescence or condensation type is formed. These kinds of structures differ in their structural–mechanical properties. Such oil compositions are basis for specific products, which are used in mining industry for dust depressing and preventing adherence of granular materials to the walls of transportation equipment. The optimal combination of influencing of external factors gives an opportunity to include bigger amount of heavy residues for decreasing the cost.

Calculation of Dipole Moment of Fractal Asphaltene Cluster

Computer simulation has been used to investigate the cluster formation of the asphaltenes. Asphaltene nanoaggregates, forming a cluster, possessed permanent dipole moments. The influence of various factors, namely, temperature of the medium, size and dipole moment of the nanoaggregates, on the dipole moment of the asphaltene cluster was studied. The orientation interactions between the nanoaggregates were demonstrated to rise with increasing specific dipole moment of the nanoaggregates. It is has been found that the dipole moment of the asphaltene cluster varies according to power law in relation to the number of the nanoaggregates, forming the cluster.

Adsorption and Aggregation of Asphaltenes in Petroleum Dispersed Systems

«Petroleum is a complex mixture of hydrocarbons which is located in the Earths crust in liquid, gaseous, and solid forms. Natural gas, heavy viscous oil and bitumens are forms of petroleum». This definition provided by а British encyclopedia is somewhat limited. Current scientific knowledge affords a more correct description of petroleum as a system containing numerous hydrocarbon components with different chemical natures. Such a correct definition allows a variety of physical properties and states related to internal structuring.

Physical chemistry of acridine adsorption onto gold surface: the influence of nanostructure as revealed by near-infrared and tipenhanced Raman spectroscopy (TERS) (Notice of Withdrawal)

This paper was presented at the SPIE conference indicated above and has been withdrawn from publication at the request of the authors.