CALCULATION OF ELASTOVISCOPLASTIC DISPLACEMENT OF WELL WALLS IN TRANSVERSAL AND ISOTROPIC ROCKS

The relevance of the work is justified by the need to improve the technical and economic indicators of well construction based on forecasting and preventing drilling tools sticking due to the narrowing of an open well bore in the intervals of transversely isotropic rocks. A mathematical model of elastic-viscous-plastic displacement of the walls of inclined and horizontal wells has been developed during the narrowing of the open borehole due to rock creep in the intervals of transversely isotropic rocks. In the program developed based on this mathematical model, the calculation of the elastic-viscous-plastic displacement of the walls of an obliquely directed and horizontal well in the reservoir of argillite from the Western Siberia deposit was carried out. As a result of the calculation, it was established that after opening the rock with bits, the cross-section of the open borehole due to the rock creep eventually takes the form of an ellipse, the small axis of which is in the plane of the upper wall of the well and decreases with time

Analysis of guest binary mixtures by tert-butylcalix[6]arene using host memory of previously bound guests

A new principle of quantitative and qualitative analysis of binary organic mixtures is offered, which is based on an ability of calixarene receptor for specific polymorphic transitions related to the composition of the analyzed guest mixture. The ability of tert-butylcalix[6]arene to remember selectively some guests bound from headspace both of pure liquids and their binary mixtures is used. The image of guest mixture remains written in metastable polymorphs of host after partial or complete guest elimination from clathrates. The memory was read using differential scanning calorimetry as the enthalpy of exothermic polymorphic transition of host collapse. This enthalpy monotonously changes with the variation of guests' ratio in mixture, unlike the enthalpies of endothermic pseudopolymorphic transitions of guest release. So, the composition of volatile binary mixture can be estimated using only one receptor and only one its parameter even in absence of preferential binding from a binary mixture of guests. This is an example of a genuine molecular recognition. © 2013 The Royal Society of Chemistry

Methylviologen mediated electrosynthesis of palladium nanoparticles stabilized with CTAC

© 2016 The Electrochemical Society. All rights reserved.Efficient electrosynthesis of ultrasmall palladium nanoparticles stabilized with CTA+ cetyltrimethylammonium cations (Pd@CTA+) was carried out in an aqueous medium by methylviologen mediated electroreduction of poorly soluble aggregates ([PdCl4]2·2CTA+)n of [PdCl4]2- anionic complex with CTA+ cations on a glassy carbon electrode at potentials of theMV2+/MV·+ redox couple. ([PdCl4]2- ·2CTA+)n aggregates are reduced directly on the electrode at a low rate and the generated metal is deposited on the electrode. In the case of mediated reduction, the metal is not deposited on the cathode, and after passing of Q = 2 F quantitative conversion from [PdCl4]2- to Pd@CTA+ nanoparticles occurs in the solution bulk. These particles are positively charged (zeta-potential is 66.8 mV) and their hydrodynamic diameter is 18 nm. Separated Pd@CTAC nanoparticles are combined into larger aggregates due to coalescence of the organic shell. The predominant shape of metal nanoparticles is an imperfect sphere with a diameter of 5 ± 3 nm, and the average size of the metal crystallites is 4.66 nm

Theoretical modeling of the carbon dioxide injection into the porous medium saturated with methane and water taking into account the CO2 hydrate formation

In this work the mathematical model is constructed and the features of the injection of warm carbon dioxide (with the temperature higher than the initial reservoir temperature) into the porous reservoir initially saturated with methane gas and water are investigated. Self-similar solutions of the one-dimensional problem describing the distributions of the main parameters in the reservoir are constructed. The effect of the parameters of the injected carbon dioxide and the reservoir on the intensity of the CO2hydrate formation is analyzed

Changes of Asphaltenes' Structural Phase Characteristics in the Process of Conversion of Heavy Oil in the Hydrothermal Catalytic System

© 2016 American Chemical Society.The composition of heavy crude oil from the Ashal'cha field (Volga-Ural Basin, Republic of Tatarstan) and the peculiarities of the changes of its asphaltenes' structural phase characteristics in the model hydrothermal-catalytic system have been studied very thoroughly. It has been established that in the water vapor media the process of destruction of the heavy crude oil high-molecular-weight components with the new light fraction formation in the presence of a natural catalyst, namely, hematite, containing iron oxide and at the temperatures of 210, 250, and 300 °C respectively, takes place which has an effect on the changes in its component hydrocarbon, fractional, and structural group composition as well as in the structural parameters of its asphaltenes. As the experiments temperature increases and the water content in the reaction system decreases, the general tendency of growth the asphaltene associates aromaticity factor revealed that in turn it is accompanied by the extension (increase) of the distance between the aromatic layers and polymethylene chain fragments under the reduction of the size of associates and the number of their aromatic layers; this results from the destructive processes course, taking place along/on the most stable asphaltene heteroatomic bonds with/accompanied by further peripheral alkyl fragments breaking off, which has been confirmed by the molecular mass of the fragments above as well as destruction of vanadyl-porphyrin complexes and increase of free radicals concentration. A significant ability of asphaltene associates to immobilize their maltenes has been revealed. Within the process of oxidation cracking at the temperature of 300°C and under the low water content in the reaction system, the increase in aromaticity and in the degree of association asphaltenes transform to carben-carboids and then to coke and are precipitated out of the oil in the solid form

The composition and thermal properties of waxes in oil asphaltenes

© 2015 Akadémiai Kiadó, Budapest, Hungary. Asphaltenes of four Russian and Kyrgyzstan crude oils were investigated with calorimetry, gas chromatography and X-ray diffraction analysis. It was established that asphaltenes contain waxes. Hydrocarbon composition and the thermal properties of waxes co-precipitated with asphaltenes and isolated by acetone from crudes oils according to the EN 12606-2 method were determined and compared. It was found that n-alkanes C40+ dominate in the waxes co-precipitated with asphaltenes. Waxes in asphaltenes are characterized by high temperature and enthalpy of melting/crystallization. Co-precipitation of high molecular weight waxes with asphaltenes is necessary to consider in order to determine the actual content and composition of asphaltenes and total content and composition of waxes in crude oil more accurately

Methylviologen-mediated electrochemical synthesis of silver nanoparticles via the reduction of AgCl nanospheres stabilized by cetyltrimethylammonium chloride

© 2017, Pleiades Publishing, Ltd.Efficient synthesis of silver nanoparticles stabilized by cetyltrimethylammonium cations (Ag@CTA+) is carried out in aqueous medium by methylviologen-mediated electroreduction of silver chloride nanospheres stabilized by surface-active CTA+ cations (AgCl@CTA+, diameter ~330 nm), on a glassy carbon electrode at potentials of the MV2+/MV•+ redox couple. The nanospheres AgCl@CTA+ can be reduced immediately on the electrode at a low rate and the resulting metal is deposited on the electrode. In the mediated reduction, the metal is not deposited on the cathode but the quantitative reduction of AgCl to Ag@CTA+ nanoparticles proceeds completely in solution volume at the theoretical charge. In aqueous solution, the nanoparticles are positively charged (electrokinetic (zeta) potential is +74.6 mV), their characteristic absorption maximum is at 423 nm and the average hydrodynamic diameter is 77 nm. Isolated Ag@CTACl nanoparticles have the size of 39 ± 15 nm. The preferential form of metal nanoparticles is sphere with the diameter of 34 ± 24 nm; nanorods are also obtained in small amounts (4%); the average size of metal grains is 8–16 nm

Fullerene mediated electrosynthesis of Au/C<inf>60</inf>nanocomposite

© 2017 The Electrochemical Society. All rights reserved. C 60 fullerene mediated electroreduction of Au(I) at potentials of the C 60 /C 60 •− redox couple was used to perform the electrosynthesis of an AuNP/C 60 nanocomposite in DCB-DMF (2:1)/0.1 M Bu 4 NCl medium. The nanocomposite consists of separate gold nanoparticles with various shapes and a mean size of ~27 ± 14 nm, as well as larger nanoaggregates of such particles, isolated in a fullerene matrix. The mean size of metal crystallites is 9–14 nm. The electrolysis occurs efficiently, and Au(I) is quantitatively reduced to Au(0) upon consumption of the theoretical amount of electricity. The resulting metal nanoparticles and the nanocomposite are not deposited on the electrode and are completely stabilized in the solution bulk. All the particles were characterized by electron microscopy methods (SEM, HR TEM) and X-ray powder diffraction (XRPD)

Using water-mimic organic compounds to activate guest inclusion by initially dry beta-cyclodextrin

© 2016 The Royal Society of Chemistry.Optimal conditions were found enabling anhydrous beta-cyclodextrin (bCD) to include target guests using small monofunctional organic compounds instead of water. Structural criteria were specified for organic substances with such water-mimic behavior. For this, a thermodynamic description of guest and water inclusion by initially dry bCD in binary systems was given using experimentally determined vapor sorption isotherms. These data perform a cooperative inclusion of each water-mimic guest and water with phase transition, and give the values of inclusion and hydration Gibbs energy, respectively. The observed inclusion cooperativity in binary systems with bCD defines a specific size-exclusion effect banning monofunctional organic compounds from entering the dry bCD phase if they exceed a threshold value of molecular size parameter near that of acetone. For larger guests, this threshold was shown to be removed in ternary systems by simultaneous inclusion with water-mimic guests or by solid-phase exchange of such guests. As well as water, water-mimic organic compounds activate the inclusion of target guests by initially dry bCD just by forming ternary clathrates, thus making all other hypotheses on the role of water and its mimics in this inclusion process excessive. These procedures may be useful for practical purposes when the presence of water does not give good results in clathrate preparation with bCD. This may provide a way for developing new techniques for the preparation of beta-cyclodextrin clathrates with various organic compounds

Expert Assessment of a Ratio of Expenses at Construction of Oil Transport Infrastructure in the Arctic

When assessing the cost of construction and operation of transport infrastructure in the early stages of the investment process, there is a problem in the formalization of some indicators of the factors influencing decision-making. The temporary impossibility to express them in monetary or comparable natural quantities leads to uncertainty in the ratio between these two groups of factors. On the example of one of the discussed objects of oil transport infrastructure in the territory of the Russian Arctic, quantitative estimates of such uncertainties are obtained, the value of which was very weighty and variable depending on the considered alternative. The authors propose an approach based on the vector representation of factors, fuzzy set theory and expert estimates, which allows developing a criterion of the limit value of uncertainty, allowing making management decisions in the problems of choice. The corresponding model giving the possibility of calculation of such criterion is constructed