Том 54, № 2 (2018)
- Год: 2018
- Статей: 14
- URL: https://journals.rcsi.science/0009-3092/issue/view/14635
Current Problems
Investigation of Thermal Effects on Samples of Coals to Determine the Prospect of Their Utilization as Sources of Gaseous Fuels
Аннотация
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.
Technologies
Isomerization of n-Hexane in the Presence of Titanium Dioxide-Supported Catalysts
Аннотация
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.
Design & Engineering
Modeling of Block of Reactors of High-Temperature Pyrolysis Process Line
Аннотация
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.
Chemmotology
Influence of the Composition of Petroleum Residual Fuel Oils on Their Colloidal Stability
Аннотация
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.
Research
Modeling of Phenomena of Drop Coalescence in oil Emulsion Breaking Processes
Аннотация
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.
Article
Alkylation of Isobutane by Olefins on Zeolite-Containing Catalysts with in-situ Catalyst Regeneration
Аннотация
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.
Composition of Shale Oil from Poorly Permeable Carbonate Rocks of Domanikovian Deposits of Dankov-Lebedyan Horizon of Romashkino Field
Аннотация
The oil generation potential of low permeability carbonate reservoir rock from the Dankov-Lebedyan horizon of the Domanikovian deposits of the Upper Devonian of the Zelenogorsk area of the Romashkino field is evaluated as a function of content and composition of the organic matter in the reservoir rock and of the composition of the shale oil extracted from the rock by organic solvents. In comparison with the shale oil produced from the carbonate reservoir rock of coeval deposits by hydrofracking of the rock formation, the extracts from the rocks contain more resins and asphaltenes and less saturated fractions predominantly comprised of high-molecular-weight n-alkanes. In model experiments, the influence of the temperatures 20, 250, 300, and 350°C on the conversion of organic matter of the Domanikovian carbonate rock in a carbonic acid hydrothermal system are studied, and the yield and quality of the extracted hydrocarbons are evaluated. It is demonstrated that the thermal effect at 200 and 250°C on the rock facilitates more intense and complete extraction of oil hydrocarbons. Processes of degradation of high-molecular-weight components and insoluble kerogen occur at temperatures above 300°C, leading to an increase in then yield of extracts from the rocks and an increase in them of the content of saturated hydrocarbons whose composition approaches the composition of the shale oil extracted from low permeability carbonate reservoir rock. Results of the investigation provide grounds for suggesting that carbonate rock of the Dankov-Lebedyan horizon contains productive formations that could become an additional source of petroleum hydrocarbons when developed by hydrothermal technologies.
Performance Study of High-Temperature Foaming Agents for Improved Steam Flooding
Аннотация
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.
Stability of Diesel-Oil-Based Drilling Fluid with Variable Water Cut at Low Temperatures
Аннотация
Diesel-oil-based drilling fluid is an oil—water emulsion used in petroleum drilling to change the formation parameters. In this paper, the rheological dispersion, and electric properties of the drilling fluid under water-cut conditions were studied as functions of the oil – water ratio. The experimental results showed that the emulsion stability depended directly on its oil—water ratio and temperature. The apparent viscosity and shear stress increased as the oil – water ration and temperature decreased. The apparent viscosity decreased with increasing shear stress at constant temperature and oil–water ratio. The diesel-oil emulsion acted as a Newtonian fluid at high oil—water ratios but demonstrated properties of a pseudo-plastic fluid at low ratios. The rheological stability continued to decline as the oil—water ratio decreased so that the emulsion was no longer suitable for use as a drilling fluid.
Experimental Analysis of Proppant Embedment Mechanism
Аннотация
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.
Numerical Simulation of Heat Flux in Unsteady Heat Transfer for Large Floating-Roof Tanks
Аннотация
Increasing demand for oil storage tanks required we develop new models for large tanks that are adapted to use under extreme conditions. In order to avoid solidification of the oil in the tank at low temperatures, we need to accurately represent the behavior of heat flux in the tank. In this paper, we propose a step-by-step algorithm for determining the heat transfer coefficient based on the law of conservation of energy, when is then applied in a discrete unsteady heat transfer equation derived using the Taylor series expansion method and solved numerically. We studied the effect of the liquid level and the average temperature in the tank on the heat flux density, and using this as the basis we were able to set up a theoretical model for optimizing the design and use of floating-roof tanks.
Oil Reservoir Sensitivities to Various Exposures
Аннотация
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.
Reliability Analysis of Annular Blowout Preventer Based on Fuzzy Relation Analysis
Аннотация
This paper considers application of the fault tree method to analyze types and reasons for failure of an annular blowout preventer (BOP). In combination with fuzzy relation analysis theory, we have calculated the fuzzy importance of basic events which can lead to failure plus the correlation coefficient for the minimum cut sets. Consequently, we can obtain the degree of correlation between the top event and the minimum cut sets. We have determined the key factors influencing stable operation of the annular BOP. Our results can provide a theoretical basis for use and improvement of an annular BOP.
Innovative Oil and Gas Technologies
A New Model of Water Injection Curves for Carbonate Reservoirs
Аннотация
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.