Том 55, № 3 (2019)

A new method was developed for the identification and quantitative determination of normal alkanes in jet fuels and kerosene fractions on the basis of simulated distillation. Normal alkanes were identified on the chromatogram by their retention times, and their concentrations were calculated by absolute calibration, the results of which correspond to the results obtained by standard addition and internal standard methods. The developed method is simple and productive and can be carried out using standard analytical equipment.

A quick inexpensive method for investigating the tendency of diesel fuels to form high-temperature deposits in the engine cylinder zone is proposed. The method can be used to model the dynamics of the deposit formation process that depends on the factors governing this process and to establish the quantitative characteristics of the influence of composition and conditions of use of fuels on deposit formation.

In this paper a new system is proposed for the storage and transportation of gas in the hydrate form (for the case of methane hydrate). The use of solid particles (Aerosil ® R202) is most effective as promoters of hydrate formation for the intended purposes. The ratio of water to transformer oil in the initial systems was constant (1:1 by weight); the content of Aerosil® R202 in “dry water” was 5 wt. %. From the obtained results it follows that the presence of “dry water” in the system accelerates the formation of the hydrate, while the transformer oil provides a self-preservation effect and thereby slow decomposition of the hydrate phase. The proportion of methane hydrate subjected to self-preservation in the presence of transformer oil is 80 times higher than for the hydrate obtained from “dry water” without any additives. The obtained data can be used in the development of hydrate methods of gas storage and transportation.

In this paper, we propose a theoretically derived improved model for characterizing the fractal features of coalbed methane reservoirs, and we compare with previously published models for conventional reservoirs. The model was verified by mercury intrusion porosimetry. The results have shown that there is no linear relationship between the normalized wetting phase saturation, wetting phase saturation, or mercury saturation vs. the capillary pressure on a log-log plot. Therefore existing models are inapplicable for a high-rank CBM formation, which is characterized by low permeability and porosity. The improved model lets us calculate the multi-interval fractal features characterizing the physical properties of the formation. We show that higher fractal dimensions mean poorer physical properties of the formation.

Drilling mud characteristics affect the stress distribution around the borehole, while anisotropic tensile strength determines the fracture behavior of the formation, but the combined effect of these factors is rarely considered in the prediction of fracture pressure. In this work, tensile strength anisotropy of shale rock was analyzed based on the Brazilian disc test (BDT), and the corresponding anisotropic tensile criteria were reviewed and contrasted with experimental results. The N-Z (Nova – Zaninetti) criterion is adopted to describe tensile strength anisotropy of shale rock. Based on the stress distribution model and the N-Z criterion, a model of shale rock fracture under the combined action of thermal and chemical factors was constructed. The solution of the model shows that chemical and thermal factors have a different effect on pore pressure distribution around the borehole. The effect of sedimentary layers, tensile strength anisotropy, in-situ stress and pore pressure on equivalent density of fracture pressure (EDFP) was also investigated. It is shown that the EDFP decreases with increasing dip angle at a given strike of the bedding plane and reaches a minimum value when the strike of the bedding plane is along the direction of the minimum horizontal stress. The decrease in EDFP caused by tensile strength anisotropy reaches or exceeds 10% of the value calculated for isotropic conditions. The more pronounced the anisotropy of strength, the smaller the possible value of EDFP. The higher the ratio of horizontal stresses and pore pressure, the more significant the effect of anisotropy on EDFP. It is also notable that increasing the temperature of the wellbore can improve EDFP parameters and enlarge the SMDW.

Gasification of mixtures of biomass (sunflower seed shells, corn cobs) and heavy oil residues (tar) with added water and preliminary mechanochemical activation of the feedstock is investigated. The influence of the gasification conditions on the yield and composition of the obtained syngas is studied.

Results are given for a study on the optimization of the composition of crude oil consisting of petroleum, fuel oil, and gas condensate to improve atmospheric distillation at an installation of the Gazprom Neftekhim Salavat Atmospheric and Vacuum Distillation Company. The results of a determination of the size of dispersed phase particles and the stability factor were used to predict the effect of the gas condensate in the crude oil on the major physicochemical properties and yield of light petroleum products. An active state of the dispersed system in the mixed crude oil was found at 40 wt.%. Atmospheric distillation of the activated crude oil permits an increase in the yield of light petroleum products by 28 wt. %.

The composition of the organosulfur compounds of the oil fraction of Arlan oil was studied using a method involving the two-step oxidation of these compounds with 30% hydrogen peroxide in the presence of an acid catalyst at 80° and 100°C. Vacuum distillation of the organosulfur compounds into narrow fractions showed that the sulfoxides obtained by oxidation of the organic sulfur compounds of the oil fraction are thiamono-, thiabi-, and thiatricycloalkanes, aliphatic sulfides, and alkylcycloalkyl sulfides. No aromatic compounds were detected in the sulfoxides. Sulfones in the narrow fractions are mainly represented by thiaindanes, alkylcyclano- and alkylbicyclanobenzthiophenes with long alkyl substituents containing from 10 to 15 carbon atoms.

A study was carried out on the precipitation of heavy fractions and the isolation of asphaltenes from a petroleum sample using supercritical carbon dioxide (SC-CO₂) as the antisolvent. The experiments were carried out in a laboratory supercritical fluid extraction device using a GAS (gas antisolvent) procedure at from 50 to 140°C and pressure from 10 to 30 MPa. We determined the effects of temperature and pressure as well as of the addition of a hydrocarbon diluent on the yields of the isolated fractions. The elemental and microelement composition was determined as well as the structural properties of the components isolated in the SC-CO₂ medium at various temperatures. An increase in temperature at pressures above 20 MPa as well as the addition of small amounts of toluene to the starting petroleum sample gave greater isolation selectivity, greater concentration of asphaltenes in the precipitated fractions, and drier solid particles. In contrast to C₇-asphaltenes, CO₂-asphaltenes have lower aromaticity, polarity, and metal content. The proposed analytical method permits the isolation of asphaltenes in only a few hours, does not require large volumes of organic solvents, and yields asphaltenes in amounts sufficient for subsequent detailed study of their composition and properties.

In this paper, we propose a method for multi-vertical well synchronous hydraulic fracturing and compare with synchronous fracturing technologies used in shale. Based on theoretical analysis and triaxial fracturing experiments, we have shown that “face interference” in multi-vertical well synchronous fracturing helps to connect the cleats and generate complex fracture networks. The developed three-step method for designing synchronous fracturing technology was tested under field conditions. The results showed that application of synchronous fracturing decreases the gas breakthrough time in the wells and increases DCBM (deep coalbed methane) production. Furthermore, stress interference generated by synchronous fracturing has a positive impact on the production rate of wells adjacent to the experimental area.

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