Том 53, № 6 (2018)

The prodigious growth of filamentous algae that has been occurring since 2011 in the littoral zone of Lake Baikal poses an acute ecological problem. Samples of algal biomass and aqueous vegetation were collected from the littoral zone of Lake Baikal and converted by hydrothermal treatment into biofuel in the presence of ammonium heptamolybdate. It was demonstrated that algal biomass from the Baikal littoral zone could be a potential source of feedstock for producing biofuel by thermocatalytic treatment. The addition of heavy-oil resids to algal and aquatic vegetation biomass increased the motor-fuel yield and modified its composition.

The feasibility of using vegetal feedstock pyrolysis products to produce motor-fuel components is examined. Results from pyrolysis of fatty-acid salts obtained by saponification of sunflower, rape, and linseed oils by various alkalis are presented. It is shown that the maximum pyrolysate yield is achieved at 500°C and is up to 52-55 wt%. The pyrolysate cannot be used directly as a fuel additive without further hydrofining because of the large amount of oxygenated compounds in it.

Determination of stability of high-viscosity marine fuel from the point of colloid chemistry concept of oil disperse systems and the need for inclusion of this parameter in the current requirements are expounded. High-viscosity marine fuels produced from residual fuel oil, visbreaking residue, and catcracking light gas oil were taken as the objects of the study. The stability of the obtained samples was determined via xylene equivalent. Also determined was the effect of dispersing additives based on hydroxyethylated amines and alkyl naphthalenes on the stability of the obtained samples of high-viscosity marine fuels.

The mechanisms of occurrence and distribution of vanadium and nickel in resins and their fractions are studied with reference to high-sulfur heavy oils of Tatarstan, Samara Oblast (region), and Kazakhstan deposits. For all the investigated heavy oils, the content of vanadium and nickel in resins increase in direct proportion to the increase in contents of these metals in the oils. The resins were fractionated into benzene and alcohol-benzene fractions by adsorption chromatographic separation on silica gel. The alcohol-benzene fractions are characterized as being more polar on account of a larger content of oxygen-bearing structural groups. The special features of vanadium and nickel content and distribution in resin fractions are disclosed for heavy oils of various production complexes.

Deviations in the activity parameters of previously synthesized catalysts derived from Y-type modified zeolite from the parameters of the basic phase composition (number of aluminum atoms in the unit cell, SiO₂/Al₂O₃ ratio, unit cell size) are described. The results of a study of the structural changes in the crystalline phase of the zeolite upon its post-synthesis modification are presented.

The effectiveness of hydrate-formation inhibitors is evaluated to select the best reagents for preventing hydrate formation in gas wells that are active-gas donors for conditions in the eastern part of Orenburg oil and gas condensate fields. A polythermal method that involves cooling at a constant rate of 1°C/h a system consisting of an inhibitor dissolved in simulated strata water and a gas mixture was used for the study. The inhibiting properties of the samples were characterized from the initial hydrate-formation temperature and the amount of gas turned into hydrate at the end of the test.

The results of a study of the composition of active forms of the catalyst formed upon degradation of the precursor, based on the results of physical modeling of a sample of high-viscosity oil having high asphaltene and resin contents, are presented. Oil-soluble iron, cobalt, and copper tallates were used as the objects of the study. The composition of the separated powder of the active form of the catalyst was determined by X-ray diffraction analysis, and the catalyst particle size was determined by scanning electron microscopy. The SARA (saturate, aromatic, resin and asphaltene) analysis data revealed a marked decrease in high-molecular-weight oil components due to thermocatalytic cracking. The basic transformation mechanism is breakdown of the high-molecular-weight compounds along the sulfur-bearing bonds, as indicated by elemental CHNS (carbon, hydrogen, nitrogen and sulfur) analysis data. It is shown that the cobalt- and copper-based oil-soluble complexes turn are converted to sulfide forms and the iron-based complex is converted to the oxide form. According to the results of scanning electron microscopic analysis of the catalyst, the particle size is about 60 nm.

A lignite graft polycondensate having water retention and dispersion properties in a water-bentonite slurry was synthesized by grafting sulfomethyl phenol-aldehyde resin (SMP) onto a humic acid (main component of lignite) scaffold through aqueous condensation polymerization. FTIR (Fourier-transform infrared) spectroscopic analysis and measurement of the molecular weight of the polycondensate confirmed successful grafting of the SMP. The resulting lignite graft polycondensate used as a drilling fluid controlled the fluid volume and exhibited rheological stability at aging temperatures as high as 200 °C. The properties of the polycondensate distinguish it from most of the high-temperature fluid-loss additives, which make the slurries excessively viscous. The colloidal properties of the water-bentonite slurry were investigated by adsorption and zeta potential experiments, and a possible mechanism was proposed.

The article presents a detailed finite-element model for investigating hydraulic fracture propagation in weakly consolidated sandstone. Elastoplastic deformation of the rock matrix, pore fluid flow, initiation and propagation of hydraulic fractures as well as flow of fracturing fluid within a fracture and leakoff into the formation are considered interdependently. The extended Cam-Clay model is used to achieve a more precise assessment of the mechanical behavior of weakly consolidated sandstone. Parametric studies are performed to investigate the effect of the fracturing parameters on the fracture patterns. The numerical results show that extremely short and narrow fractures are formed if low-efficiency fracturing fluid is used to initiate fractures in weakly consolidated sandstone with a zone of shear dilation formed on both faces of the fracture. In contrast, longer and wider fractures initiation of which is desirable in frac-pack (hydraulic fracturing) operations with the use of proppant may be obtained with the use of high- efficiency fracturing fluid and more compact zones are created near the fracture. However, the structure of the compaction zone produces an insignificant decrease in permeability. It is also shown that plastic deformation of the rock matrix has a significant impact on the geometry of a fracture, and this must be taken into account in the design of frac-pack operations with the use of proppant in weakly consolidated sandstone reservoirs.

The properties of conventional shale hydration inhibitors were studied using samples of Longmaxi shale. The inhibition was evaluated by the rolling recovery test, linear swelling rate, and clay interlayer spacing. The results indicate that K₂SiO₃ inhibits clay hydration far better than other inorganic shale inhibitors while polyamine is superior to other organic shale inhibitors of clay hydration. Alkaline solution is more effective in suppressing shale dispersion. A neutral environment has little impact on this parameter. On the contrary, an acidic medium can even promote it. Most of the inhibitors are incapable of suppressing simultaneously clay dispersion and expansion. Therefore, they should be used in conjunction to suppress synergistically clay hydration, dispersion, and expansion.

The physicochemical and performance properties of biodiesel fuels derived from food industry wastes and from technical vegetable oils and animal fats are investigated. Additives that improve the low-temperature and antioxidant properties of blends of biodiesel with petroleum fuel are chosen. A suggestion is offered regarding the possibility of raising the biodiesel concentration in fuel blends to as much as 30%.

Prospects for the use of furfural derivatives as high-octane additives to gasoline are examined by examining their physicochemical and performance properties. Knock resistance data, toxicity indices, and engine-bed test results for furan compounds, furfuryl ethers, furfurylamine, and other furfural derivatives are analyzed.

A technology has been developed for producing an asphalt binder for road construction based on oil distillation residues modified with elemental sulfur. A blend of asphalt base and elemental sulfur was exposed to the action of ultrasound with a vibratory power of 2.5 W/cm² and a frequency of 20 kHz at 160°C. The blend was heated exclusively by acoustic vibration energy. Sulfur-asphalt samples conforming to the BND 130/200 brand were obtained. Energy consumption can be reduced and asphalt binder production process can be accelerated by ultrasonic blending.

Asphalt-resin-wax deposits formed during modeling of the process of formation of deposits from oil considered hard to extract are studied. The mechanisms of asphalt-resin-wax deposition that occurs due to different contents in them of high-molecular-weight components and their properties are disclosed. It is shown that oil paraffin hydrocarbons and asphaltenes are redistributed between the oil and the asphalt-resin-wax deposited from it.

The authors’ affiliations should read 1. Mining Technology Institute, Taiyuan University of Technology, Taiyuan, China.