Vol 53, No 2 (2017)

The antiknock properties of blends of 2-methylfuran and 2,5-dimethylfuran with a reference fuel containing toluene are studied. The octane numbers of blends of these substances in various concentrations and the change in sensitivity of the fuel are calculated. In the research method it is shown that the octane number of the blend reaches a maximum at an additive concentration of 10 vol. %, while the sensitivity of the fuel increases to a smaller degree when 2-methylfuran is used.

A method is examined for cleaning oils using monoethanolamine and isopropyl alcohol, which permits the purification of synthetic oils for their subsequent use as dispersion media in the production of plastic lubricants. The compositions of plastic lubricants derived from Solidol J and Lithol-24 analogs produced from used oils were determined. The basic physicochemical and performance properties of experimental lubricant compositions were evaluated. The properties of plastic lubricants derived from used oils were found to be comparable or even superior to the properties of commercial analogs produced from expensive base oils.

The physicochemical properties of the middle distillates of exhaustive refining of crude oil at one of the Russian refineries are studied from the standpoint of their utilization as components of low-viscosity marine fuels. The performance properties of diesel fractions after hydrofining and of light gas oils of catalytic cracking and delayed carbonization are determined and compared. The physicochemical and performance properties of the studied fractions are found to depend on the hydrocarbon composition of the fractions. Based on the noted dependences, the optimum component composition of low-viscosity marine fuel is developed and recommended for introduction.

Delayed carbonization is one of the most dynamically developing technologies in global petroleum processing. The basic factors determining the material balance and the quality of carbonization products are process parameters and quality of the feedstock used. However, data on the dependence of yield of gaseous and liquid carbonization products on the quality of the feedstock are absent in the domestic literature. This paper presents the developed mathematical models of the yield of heavy oil residue carbonization products, which help control products yield by varying the proportions of the components in the feedstock, taking account of the change in carbonizability of each component of the feedstock.

We present the results of a laboratory experiment on multistage hydraulic fracturing using a gel solution as the fracturing fluid, utilizing a laboratory setup for simulating hydraulic fracturing under triaxial stresses. As a result of the experiment, a fracture network was formed in a cubic rock specimen. We found that an almost planar fracture was formed during the first fracturing stage, while a concave (bowl-shaped) fracture was formed during the second stage. Interaction between the stress fields created by the two main hydraulic fractures (stress interference) caused growth of secondary cracks parallel to the simulated wellbore, but in this case led to a decrease in the width of the subsequent main fracture. We established that the penny-shaped fracture model is more suitable for predicting the geometry of hydraulic fractures in horizontal wells than two-dimensional (rectangular) fracture propagation models (the Perkins – Kern – Nordgren (PKN) model, the Khristianovic – Geertsma – de Klerk (KGD) model). Special attention needs to be paid to fracture spacing design in multistage hydraulic fracturing in horizontal wells.

Based on the characteristics of water injection into the reservoir and using the streamline calculation method and the unit analysis method, we derive a computational model for non-Darcy seepage production from a rhombus reverse five-point well pattern in a low-permeability reservoir. In order to test the adequacy of the method, we used data on fluid seepage from a real low-permeability reservoir. The method identified a relationship between the startup pressure gradient, the hole spacing, the row spacing, and the production capacity, and also provided a basis for designing a model for a rhombus injection well pattern in low-permeability reservoirs.

The influence of mobile and bound water on seepage capability of a low-permeability sandstone gas reservoir was studied and formulas were derived to calculate gas well production rate using cores from Xujiahe low-permeability sandstone gas reservoir in China. It is shown that mobile water in the well exerts a stronger negative effect on gas production than bound water. If the pressure gradient is too steep, a small part of the bound water may turn into mobile water, whereupon the gas seepage efficiency falls. So, use of controlled pressure is recommended for gas production, which in the end enhances the gas recovery efficiency of the reservoir.

This paper is the first attempt to simulate the mechanism of N₂ foam flooding in an ultra-high water cut reservoir using the CMG-STARS reservoir simulator with a non-isothermal module. The simulation results showed that N₂ foam flooding had the potential to improve oil recovery in a reservoir with high water cut up to 97.6%. The best strategy was simultaneous injection of N₂ and foaming agent of 0.3-0.4 wt. % concentration at a gas—liquid ratio of 2-2.5 and total porosity volume (PV) of 0.3-0.35. Under these conditions, the recovery was expected to increase by 1.2%. The experimental results indicated that oil recovery could be enhanced by N₂ foam flooding in a medium-permeability light-oil reservoir with an ultra-high water cut.

A physical model has been developed for the aquathermolysis of heavy crude oil from the Ashalchinsk oil field at 250°, 300°, and 350°C. Nickel and cobalt carboxylates were used as oil-soluble catalyst precursors. In the presence of a hydrogen proton donor at 300°C, the oil content was found to rise considerably and the resin content was found to decrease by a factor of 1.8, which leads to a decrease in crude oil viscosity by 91% and a decrease in density from 960 to 933 kg/m³. The hydrocarbon composition of the liquid aquathermolysis products was studied by chromate-mass spectrometry. The average molecular weight of the asphaltenes was determined by matrix-assisted laser desorption/ionization (MALDI) spectrometry. The maximum disproportionation of the hydrocarbons into n-alkanes, alkylcyclohexanes, and alkylbenzenes occurs at 300° and 350°C. The composition of the hydrogen proton donor (tetralin) conversion products at these aquathermolysis temperatures was determined.

The results of determination of thermal stability of mineral and semisynthetic motor oils are presented. The thermal stability criterion is validated and the link between it and the wear resistance properties of motor oils is determined.

As coal resources in China are becoming scarcer, development and exploitation of soft coal seam is becoming more important. However, the existing technology of drilling of structurally loose soft coal seams is not well developed. A new technology, in which foamed fluid is injected for drilling, was developed and tested in four drill holes in the Zou coal mine, Huaibei. The problems of borehole collapse or pipe-sticking accidents that may occur in the drilling process and ways of their solution were analyzed. In field tests, drilling of hole 1 could not be completed because of lack of foam circulation perhaps because of resistance to foam flow due to high foam viscosity, small diameter of the triangular drill pipe used, and/or air pressure being too low to overcome resistance to foam flow. Drilling of the other three holes were completed to depths of more than 200 m, which demonstrated that the new foam drilling technology can be used to effectively increase drilling depth with reduced coal dust pollution.