卷 54, 编号 2 (2018)

One of the promising ways of expanding energy resource base is production of combustible gas from coalbeds. The yield of gaseous components from samples of Visean coals of Tatarstan upon thermal impact was studied in this work by combined thermogravimetric and IR spectrometric method. It is demonstrated that methane begins to appear actively at 384-405°C, depending on the test coal sample. In this process, the yield of methane could be as much as 30 wt. % and higher, which confirms the prospect of getting gaseous fuel from Visean coal deposits by thermal impact.

The catalytic properties of titanium dioxide-supported catalysts in n-hexane isomerization reactions have been studied. The hexane isomerization activity was found to increase in the series Fe/TiO₂ < Ca/TiO₂ < Ni/TiO₂. The most active Ni/TiO₂ catalyst is effective in two temperature ranges: moderate temperatures (150-300°C) for a bond shift mechanism and high temperature (350-400°C) for a cyclic mechanism with intermediate five-membered ring information along with a bond shift mechanism. The formation of dispersed nickel leading to a hydride phase during the reductive activation of Ni/TiO₂ was proposed. Ionic hydrogen and nickel facilitate enhanced Ni/TiO₂ catalyst activity.

The results from mathematical modeling of a block of reactors of a high-temperature hydrocarbon pyrolysis line are presented. Models of tube furnaces for homogeneous pyrolysis with variously designed coils are described as ideal-displacement reactors. Application of a determinative approach to the reaction mechanism and determination of the kinetic parameters for thermal decomposition of hydrocarbons and their use for describing the processes occurring in SRT-1 and SRT-2 pyrolysis furnaces showed agreement between the calculated relationships and the experimental data.

Saturated, aromatic, resin, and asphaltene (SARA) group and fractional composition of 14 samples of marine residual fuel oils and components suitable for their production is studied. Analysis of the results of laser Fourier-difractometric study of solutions of these samples in isooctane made it possible to develop a quantitative method of assessment of their colloidal stability. Correlative relationships of the composition and colloidal stability of the studied asphaltene-containing and asphaltene-free petroleum products are derived. The inapplicability of the term “straight-run” for assessment of colloidal stability of residual fuels is shown experimentally.

A diffusion model of adsorption layer from asphalto-resinous substances on water drop surface is proposed and a formula for determining its thickness is given. A model of combined drop coalescence and disintegration in an isotropic turbulent flow is developed. Equations for determining evolution of the number of drops and their size with time, which depend on the frequency of disintegration and coalescence, are proposed. At low Weber numbers (We < 1) these models agree satisfactorily with the available experiment data.

One solution of the problem of deactivating zeolite-containing alkylation catalysts is to use supercritical conditions in the process where the supercritical hydrocarbon fluid that is formed removes the high-molecular-weight condensation products formed on the catalyst surface. This paper reports the results of prolonged pilot tests of catalysts based on modified polycation-decationized Y zeolites in an ultrastable form in alkylation with in-situ catalyst regeneration.

Performance studies of foaming agents in terms of thermal endurance, foaminess, foam stability, and structural and morphological robustness are carried out to investigate the mechanism of steam overlay and channeling that arise during steam flooding of heavy-oil reservoirs. The results show that agent CX-4 possesses excellent thermal endurance, foaminess, and foam stability. High temperatures did not affect the foaming-agent structure although the foam hexagonal structure weakened. The absorbed films of foam bubbles have centered ring structures intertwined with each other and overlapped significantly. The spatial distribution and three-dimensional foam structure become slightly worse. The foaming agent consists mainly of the four elements S, C, Na, and O. High-temperature treatment did not affect the elemental composition and molecular structure.

Proppant embedment in hydraulic fracturing can reduce remarkably the fracture width and thus damage the fracture conductivity. This paper describes a study of the proppant embedment mechanism. Two groups of experiments were carried out. A proppant embedment mechanism was proposed. An analysis showed that proppant embedment is not an elastic process but could be a plastic or even failure process depending on the surface microstructure of the formation core.

The properties of Hongnan 2 block T₁ oil reservoir in Xinjiang oilfield were analyzed in terms of petrological characteristics, rock granularity, clay composition, and other aspects. Experiments based on these results studied the sensitivities of the reservoir to velocity, acidity, alkalinity, stress, and water. The results showed moderate velocity sensitivity damage with an index in the range 42-56% and a critical flow velocity in the range 0.25-0.30 mL/min. Moderate and strong water sensitivities with indices varying from 52 to 65% and critical salinities from 5,000 to 10,000 mg/L were found. Water injected into a well should have salinity ≥ 10,000 mg/L to avoid water sensitivity damage. Weak sensitivity to alkalinity with an index varying from 31 to 36% with a critical pH of 8 was observed. Moderate and strong sensitivity to acidity was found for HCl fluid (15%); extremely strong, HCl (12%) + HF (3%); extremely strong, HCl (10%) + HF (3%) + HBF₄ (8%); and no sensitivity, HCl (10%) + HBF₄ (8%). The reservoir could be acidified by using HCl (10%) + HBF₄ (8%). Significant changes in the reservoir core structure were not observed with large pressure differences. The critical pressure varied from 2 to 3.5 MPa. The permeability damage rate ranged from 13.33 to 18.68%. The stress sensitivity was weak.

In Tahe oilfield of Xinjiang, China, the carbonate reservoir displays poor porosity and permeability in its matrix, while the fracture-cave formation is distributed in a random, discreet and discontinuous way. As the oil recovery with water injection mechanism shows, the water injection curve of the carbonate reservoir differs from that of the sandstone reservoir. For discontinuous carbonate reservoirs, the reservoir type can be determined from the shape of the water injection curve. For karst-cave reservoirs with high permeability, on the other hand, the new theoretical model of the water injection process can be adopted to calculate the volume of a single cave or a multiple of caves, crude oil, and formation water. The calculated results agree well with the practical results.