Анализ эффективности применения технологии кластерного гидравлического разрыва пласта в низкопроницаемых коллекторах нефтяных месторождений

Объектом исследования является технология кластерного ГРП. Цель исследования – анализ эффективности применения технологии кластерного ГРП в низкопроницаемых коллекторах нефтяных месторождений. В процессе исследования был подробно рассмотрен механизм проведения кластерного ГРП. Проведен анализ геологических условий применения данной технологии. Изучен процесс подбора рабочих агентов кластерного ГРП. Выполнен анализ технологического процесса кластерного ГРП на нефтяных месторождениях. В результате исследования выявлен положительный эффект кластерного ГРП и разработаны рекомендации по развитию данной технологииThe object of the study is the technology of cluster hydraulic fracturing. The purpose of the study is to analyze the effectiveness of the application of cluster hydraulic fracturing technology in low-permeable reservoirs of oil fields. In the course of the study, the mechanism of cluster hydraulic fracturing was considered in detail. The analysis of geological conditions of application of this technology is carried out. The process of selecting working agents for cluster hydraulic fracturing is studied. The analysis of the technological process of cluster hydraulic fracturing in oil fields is carried out. The study revealed the positive effect of cluster hydraulic fracturing and developed recommendations for the development of this technolog

Pressure-induced tuning of lattice distortion in a high-entropy oxide

As a new class of multi-principal component oxides with high chemical disorder, high-entropy oxides (HEOs) have attracted much attention. The stability and tunability of their structure and properties are of great interest and importance, but remain unclear. By using in situ synchrotron radiation X-ray diffraction, Raman spectroscopy, ultraviolet–visible absorption spectroscopy, and ex situ high-resolution transmission electron microscopy, here we show the existence of lattice distortion in the crystalline (Ce$_{0.2}$La$_{0.2}$Pr$_{0.2}$Sm$_{0.2}$Y$_{0.2}$)O$_{2−δ }$ HEO according to the deviation of bond angles from the ideal values, and discover a pressureinduced continuous tuning of lattice distortion (bond angles) and band gap. As continuous bending of bond angles, pressure eventually induces breakdown of the long-range connectivity of lattice and causes amorphization. The amorphous state can be partially recovered upon decompression, forming glass–nanoceramic composite HEO. These results reveal the unexpected flexibility of the structure and properties of HEOs, which could promote the fundamental understanding and applications of HEOs

Is Li-doped MgAl2O4 a potential solid electrolyte for an all-spinel Li-ion battery?

The ionic conductivity of Li-doped MgAl2O4 (LMAO), which is considered as a potential solid electrolyte for an all-spinel Li-ion battery, has not been investigated so far. Only NMR studies, which give information about the mobility or the Li-ion diffusion on local (microscopic) level, are performed on this system, but they do not give information about the long-range Li-ion diffusion, which is required for solid electrolyte application. Therefore, ionic conductivity study i.e., impedance spectroscopy, which provides insight into Li-ion diffusion on microscopic scale, is of great importance. The results reported here reveal for the first time ionic conductivity of LMAO ceramics and give insight into whether this material system has a potential for application as a solid electrolyte. The LMAO powders, with an average grain size of 55 nm, are synthesized by nebulized spray pyrolysis (NSP) and processed into dense ceramics (95-98% TD) using spark plasma sintering (SPS). The decrease of the lattice parameter with Li-doping indicates the incorporation of lithium into the spinel structure. X-ray diffraction structural analysis shows a systematic decrease of the occupancy of Al-octahedral (16d) sites with Li-doping, indicating that a fraction of the Li+ ions are located on the octahedral (16d) sites, and at the same time in order to retain charge neutrality, some of the Al3+ ions are moved to the tetrahedral (8a) sites. The conductivity study reveals that even at a high temperature (similar to 300 degrees C) the value of the Li-ion conductivity of LMAO, in the order of 10(-7) S.CM-1 is poor and at room temperature it is substantially lower (similar to 10(-14) S.cm(-1)). While the origin of this low conductivity remains unclear, it could be related either to the nano- and microstructure of the sintered ceramic or to the distribution of Li+ ions inside the lattice. Nevertheless, the results presented here suggest that more conductivity studies have to be performed in order to draw a final conclusion about potential of LMAO ceramics for application as a solid electrolyte in Li-ion batteries. (C) 2016 Elsevier B.V. All rights reserved

Chemical Vapor Synthesis and Structural Characterization of Nanocrystalline Zn1-xCoxO (x=0-0.50) Particles by X-ray Diffraction and X-ray Absorption Spectroscopy

WOS: 000277776900003Nanocrystalline Zn1-xCoxO (x = 0-0.50) particles are produced by chemical vapor synthesis using laser flash evaporation as a novel precursor delivery method. The crystal and local structure of the samples is studied using X-ray diffraction and X-ray absorption spectroscopy. A single wurtzite phase is observed in samples with cobalt contents as high as = 0.25 (actual content is 0.33 determined by atomic absorption spectroscopy). X-ray absorption spectra show that the Co2+ ions are incorporated into the ZnO wurtzite lattice substituting Zn2+ ions for cobalt contents between x = 0.001 and x = 0.20. Only small lattice deformations are observed in these solid solutions.German Research Foundation (DFG) through the Collaborative Research CenterGerman Research Foundation (DFG) [SFB 445]The financial support by the German Research Foundation (DFG) through the Collaborative Research Center SFB 445 is gratefully acknowledged. The authors thank Dr. Nadia Leyarovska from APS, Argonne National Laboratory, IL, for help at the EXAFS beamline and Andreas Gondorf and Prof. Dr. Axel Lorke, Experimental Physics, University of Duisburg-Essen, Germany, for FT-IR measurements

Garnet-Type Li 7 La 3 Zr 2 O 12 Solid Electrolyte Thin Films Grown by CO 2 -Laser Assisted CVD for All-Solid-State Batteries

The detailed characterization of garnet-type Li-ion conducting Li7La3Zr2O12 (LLZO) solid electrolyte thin films grown by novel CO2-laser assisted chemical vapor deposition (LA-CVD) is reported. A deposition process parameter study reveals that an optimal combination of deposition temperature and oxygen partial pressure is essential to obtain high quality tetragonal LLZO thin films. The polycrystalline tetragonal LLZO films grown on platinum have a dense and homogeneous microstructure and are free of cracks. A total lithium ion conductivity of 4.2·10−6 S·cm−1 at room temperature, with an activation energy of 0.50 eV, is achieved. This is the highest total lithium ion conductivity value reported for tetragonal LLZO thin films so far, being about one order of magnitude higher than previously reported values for tetragonal LLZO thin films prepared by sputtering and pulsed laser deposition. The results of this study suggest that the tetragonal LLZO thin films grown by LA-CVD are applicable for the use in all-solid-state thin film lithium ion batteries

Field assisted sintering of fine-grained Li7−3xLa3Zr2AlxO12 solid electrolyte and the influence of the microstructure on the electrochemical performance

The synthesis and processing of fine-grained Li7−3xLa3Zr2AlxO12 (x = 0.15, 0.17, 0.20) solid electrolyte (LLZO) is performed for the first time using a combination of nebulized spray pyrolysis (NSP) and field assisted sintering technique (FAST). Using FAST, the grain growth is suppressed and highly dense ceramics with 93% of the theoretical density are obtained. A tetragonal lattice distortion is observed after the sintering process. Although this structural modification has been reported to have lower Li-ion mobility compared to the cubic modification, the total conductivity of the sample at room temperature is found to be 0.33 mS cm−1, i.e. comparable to phase-pure cubic LLZO. The activation energy of 0.38 eV is also comparable to the literature values. Galvanostatic cycling of a symmetrical cell Li|LLZO|Li shows a good cycling stability over 100 h. The interfacial resistance in contact with Li-metal is determined using alternating current impedance spectroscopy to be 76 Ω cm2 and 69 Ω cm2 before and after cycling at different current densities, respectively

Direct preparation of ultrafine BaTiO3 nanoparticles by chemical vapor synthesis

Ultrafine, crystalline barium titanate (BaTiO3) nanoparticles were synthesized by chemical vapor synthesis (CVS). Titanium- and Barium-organometallic solid precursors were vaporized using a laser flash evaporator as precursor delivery unit. The process parameters such as precursor ratio, reactor temperature, and reactor length were varied in order to find the optimal conditions to allow the direct synthesis of crystalline particles with the stoichiometric composition. Crystalline, spherical nanoparticles with a size of about 8 nm, free of barium carbonates and with low degree of agglomeration were obtained using a precursor ratio of Ba/Ti = 4, a maximum reactor temperature of 1,700 A degrees C, and a total reactor length of 165 cm. The potential of the CVS process for the synthesis of nanoscaled, impurity-free, and phase-pure BaTiO3 particles in one step is presented. The results demonstrate the capabilities of the CVS method, not only for the preparation of BaTiO3, but also for many other multi-component systems

On processing-structure-property relations and high ionic conductivity in garnet-type Li 5 La 3 Ta 2 O 12 solid electrolyte thin films grown by CO 2 -laser assisted CVD

This study reports on the optimization of garnet-type Li-ion conducting Li5La3Ta2O12 (LLTaO) solid electrolyte thin film growth by CO2-laser assisted chemical vapor deposition (LA-CVD) and the films' detailed structural as well as electrochemical characterization. By adapting the LA-CVD process parameters, high quality LLTaO films with tailored microstructures are successfully grown, which allows to correlate the films' microstructure and phase composition with their electrochemical performance. Explicitly, the influence of grain boundaries on the ionic conductivity is studied, and possible strategies to lower the grain boundary resistance are given. As deposited LLTaO films show a total ionic conductivity of 7.8·10− 6 S·cm− 1 at 298 K (activation energy of 0.66 eV). By applying a post-annealing treatment the total ionic conductivity is improved up to 3.8·10− 5 S·cm− 1 at 298 K (activation energy of 0.52 eV). This is among the highest ionic conductivities reported for Li-ion conducting garnet-type thin films so far. A better suitability of garnet-type Li5La3Ta2O12 films for fundamental research as well as for application in all-solid-state thin film lithium ion batteries compared to commonly investigated Li7La3Zr2O12 films is proposed and discussed