Vol 54, No 6 (2019)

The article presents the results of tests of a system of catalysts developed for demetallation and desulfurization of oil residues to produce low-sulfur marine fuel. A fixed catalyst bed was used. The optimum feedstock hydrogenation conditions were chosen: pressure 15 MPa, process temperature 360-420°C, and feed space velocity 0.5/124. The prolonged tests of the developed catalysts system were conducted successfully.

A new catalyst, based on newly synthesized inorganic superacids, was developed for the isomerization of light hydrocarbons. A series of mixed heteropoly anions with a modified Keggin structure containing different transition metals (including platinum group metals) were synthesized for this purpose. The technology for the production of superacidic catalysts with a coating of modified heteropoly complexes of the Keggin series on different supports was developed. The Brønsted and Lewis acid sites of the developed superacidic oxo complex catalyst deposited on various supports were investigated.

MoS₂/Al₂O₃ and NiMoS₂/Al₂O₃ catalysts were prepared by incipient wetness impregnation of alumina using aqueous solutions of 12-molybdophosphoric heteropolyacid and nickel citrate. Unsupported catalysts were prepared by etching a support made from MoS₂/Al₂O₃ using hydrofluoric acid (Et-MoS₂) and thermal decomposition of aluminum tetrathiomolybdate (Ref-MoS₂). The activity of the catalysts in hydrodeoxygenation decreases in the series NiMoS₂/Al₂O₃ = Et-MoS₂ > MoS₂/Al₂O₃ > Ref-NiS₂. On the other hand, the selectivity relative hydrogenation of oleic acid has a different order: Et-MoS₂ > MoS₂/Al₂O₃ > Ref-MoS₂ > NiMoS₂/Al₂O₃. The unsupported Et-MoS₂ catalyst has similar activity to NiMoS₂/Al₂O₃ in hydrodeoxygenation and the highest selectivity, which indicates virtually completion of the hydrodeoxygenation reaction through a hydrogenation pathway without the formation of CO or CO₂. These gases display strong inhibiting properties and have a detrimental eject on the environment.

Fuel development for solvent deasphalting (SDA), by means of which it is possible to obtain high yields of deasphalted oil (DAO) with acceptable quality for subsequent refining in catalytic cracking processes and hydrocracking in particular, is nowadays becoming increasingly important. In this paper, an experimental study of the SDA of tar (vacuum residue) with n-pentane at various extraction temperatures and pressures was undertaken, and this made it possible to determine the effect of the phase state of the solvent on the yield, composition, and properties of the separation products,. It was shown that transfer of pentane from the liquid phase state to the region of a subcritical and then supercritical fluid (SCF) increases the solubility of the tar components and the yield of the DAO for fixed values of the solvent density. Despite some decrease in the quality of the DAO in the case of supercritical extraction at temperatures close to the critical temperature of the solvent (220°C), the phase state of the pentane has little effect on the metal content of the products, the carbon residue content of the DAO, and the softening point of the asphalt for the given yields.

Mixtures of magnesium chloride and MeOH were studied as mixed thermodynamic inhibitors of hydrate formation. The equilibrium P,T-conditions for methane hydrate decomposition in the presence of binary solutions H₂O—MeOH and H₂O—MgCl₂ and ternary solutions H₂O—MeOH—MgCl₂ were determined using an isochoric method in a stirred autoclave. Measurements were made at pressures of 3.5-9.5 MPa; MeOH concentrations, 0-25 mass%. The salt content in the aqueous solutions was constant at 5 mass%. The results showed that mixed samples containing MeOH and MgCl₂ gave the largest thermodynamic shifts of hydrate formation as compared to samples with MeOH at the same inhibitor mass fraction. The larger thermodynamic shift was related to synergism between the affects of MgCl₂ and MeOH in the aqueous solution.

We propose an artificial core plate model for studying seepage flow patterns in fractured poor and thin reservoirs. We have analyzed the pressure gradient distribution, mapped sections with different seepage flow patterns, and studied the qualitative and quantitative parameters of the seepage flow patterns for liquid in thin and poor reservoirs. The experiments have shown that the seepage flow pattern in thin and poor reservoirs depends on the permeability and heterogeneity of the rock and the presence of cracks. The presence of cracks can compensate for the negative impact of low permeability and heterogeneity of the rock. From the experimental results, we can identify three sections in the rock with different seepage flow patterns. Fracturing can significantly reduce the size of the no-flow section (by at least 72%) and can increase the size of the quasilinear seepage flow section (by at least 86%).

The numerical simulation of air infection is carried out to further exploit the residual oil in low permeability reservoirs. CMG-STARS software was used to establish a 3D reservoir model for numerical simulation and comparative characteristics of the processes of air injection and waterflooding of the oil reservoir, depending on the oil parameters, well pattern and well spacing. Analysis of the mechanism for improving production efficiency for these technologies is carried out. The results showed that the effect of air injection on oil recovery is more pronounced than that of waterflooding. The best results for air injection were obtained with a 9-spot well pattern and a 250 m distance between wells, as well as with simultaneous injection into groups of wells in different oil-containing layers. It is determined that air injection is an effective way to develop and enhance oil recovery in low permeability reservoirs.

Air drilling technology in some cases improves wellbore penetration and stability. The annulus gas temperature is usually regarded to be the same as the formation temperature. However, the gas temperature is greatly influenced by the pressure and in situ viscosity because of its compressibility. Joule—Thompson expansion and cooling as the gas passes through the bit nozzles causes the gas temperature to differ significantly from that of the formation. In the present paper, a method for calculating pressure—temperature coupling over the whole wellbore is proposed. Radial and tangential thermal stresses are determined considering heat exchange between wellbore fluid and the formation. Then, the wellbore wall stability under the influence of the thermal stresses is analyzed. The calculated wellbore-rock and thermal stresses show that the low temperature in the well bottom causes tensile stresses around the wellbore wall. Therefore, shear stresses in the rock, the effective stress of the wellbore wall, and the collapse pressure decrease, which has a positive effect on the wall stability.

A method for hydraulic fracturing of a formation that includes injection of a fracturing fluid with sealing balls to reduce filtration of the fracturing fluid is known. The balls are selected so that fissures into which fracturing fluid is diverted are reliably sealed temporarily. The problem of sluicing and returning the balls arises when the well is put into operation. Steel balls or high-molecular-mass polymeric materials are currently most widely used. Sluicing high-density steel balls is difficult. Polymer balls are easily deformed so they are also difficult to return. The present work proposes the use of aluminum-alloy balls and studies the electrochemical dissolution mechanism of the material in the formation. The developed aluminum-alloy balls had rather good solubility and high mechanical properties. Use of sealing balls made of this material provided effective transfer of the working pressure during hydrofracturing and avoided the problem of returning the balls. Also, high-strength alloys that can be dissolved could find applications in various fields.

An analysis is presented for thermodynamic aspects of the preparation of synthesis gas through methane conversion and the related synthesis of various classes of hydrocarbons. Methods of chemical thermodynamics were used to analyze the equilibrium composition of the system under given conditions. The thermodynamic study showed that the H₂/CO ratio in methane conversion depends significantly both on the reaction temperature and pressure as well as on the nature and amount of oxidizer. The thermodynamic probability for the formation of various classes of compounds depending on the synthesis gas composition was calculated.

The goal of this work was to determine the effectiveness of various surfactant-based reagents and disclose the interrelationships of the effectiveness of the reagent and the type of the soil being cleaned, the concentration of the working reagent solution, and the alkalinity of the solution. It was found that reagents containing anionic and nonionic surfactants and their working solutions having high pH values are most effective. However, this parameter is not decisive for both petroleum hydrocarbons and natural organic compounds. Study of the influence of sorption capacity of soil matrices on the effectiveness of soil cleaning by reagent treatment revealed that sorption of molecules of contaminating matters and molecules of surfactants markedly reduces the overall effectiveness of leaching out of organic matters from the soils.

The article discusses the potentials of production of base oils in Russia by GTL technology. The quality of the base oils produced currently in Russian enterprises are analyzed. The possibility of producing base oils by the GTL process, taking account of the analysis of data on synthesis gas production by various conversion methods and the experience of application of GM process in foreign enterprises, is discussed. The experience of using different types of Fischer-Tropsch synthesis reactors is analyzed and, based on the obtained data, recommendations are offered for their use in Russia.

A new production technology for low-sulfur high-viscosity marine fuel via indirect hydroprocessing of atmospheric residue using hydrotreating of vacuum gasoil and heavy coking gasoil mixtures obtained from processing atmospheric residue over NiW/Al₂0₃ catalyst synthesized using a Keggin heteropolyacid as a precursor and citric acid as a chelating agent is presented. Hydrotreating of mixed feedstock with 10-20 wt.% of the second component at 360°C, 5 MPa H₂ pressure, 1.0 h-1 liquid hourly space velocity (LHSV), and 800 Nm³/m³ H₂/feedstock ratio produced an RMB 30 marine fuel component with <0.1 wt.% S.

The corresponding author of the article is Guo Ying, E-mail: majian258741@163.com.

The original version of the article was revised: Due to a typesetting error, the last three author names were inadvertently omitted.