Gas Permeability of Sandy Sediments: Effects of Phase Changes in Pore Ice and Gas Hydrates

Gas hydrates are potential energy resources which can be formed at low temperature and high pressure. The number of recoverable gas hydrates are limited due to the specific temperature, pressure conditions and technical limitations of gas production. Various production methods have been studied around the world to overcome these technical limitations. Gas production methods from gas hydrates are divided into methods of dissociating gas hydrates and non-dissociating gas hydrates. The dissociation methods including depressurization method, thermal injection method, and chemical inhibitor injection method can decrease in effective stress of the ground due to phase conversion. On the other hand, CH4-CO2 replacement method is geomechanically stable because it does not dissociate gas hydrates. Also, CH4-CO2 replacement method has the advantage of sequestering carbon dioxide while producing methane. However, CH4-CO2 replacement method has the disadvantage such as low production efficiency and understanding kinetics of gas production. In this study, soaking, gas permeability of gas hydrate layer and hydrate saturation are considered in order to promote the production efficiency of CH4-CO2 replacement method. Results show that production efficiency increases with the number of soaking process, the higher gas permeability and hydrate saturation. According to the experimental results in this study, the production efficiency can be increased by considering the soaking time, procedure and selecting the proper gas hydrates site.AcknowledgementThis work is supported by the Korea Agency for Infrastructure Technology Advancement(KAIA) grant funded by the Ministry of Land, Infrastructure and Transport (Grant 20CTAP-C152100-02). Also, it is supported by partial funding from NPRP grant # NPRP8-594-2-244 from the Qatar national research fund (a member of Qatar Foundation) and&#160; the Ministry of Trade, Industry, and Energy (MOTIE) through the Project &#8220;Gas Hydrate Exploration and Production Study (20-1143)&#8221; under the management of the Gas Hydrate Research and Development Organization (GHDO) of Korea and the Korea Institute of Geoscience and Mineral Resources (KIGAM).

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The Interpretation of Crystal Lattice Images

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010009600x ◽

1972 ◽

Vol 30 ◽

pp. 550-551

Author(s):

J. M. Cowley ◽

Sumio Iijima

Keyword(s):

Crystal Orientation ◽

Diffraction Theory ◽

Phase Changes ◽

Electron Wave ◽

Crystal Lattices ◽

Heavy Atoms ◽

Lattice Images ◽

The Right ◽

Intuitive Interpretation ◽

Suitable Approximation

The imaging of detailed structures of crystal lattices with 3 to 4Å resolution, given the correct conditions of microscope defocus and crystal orientation and thickness, has been used by Iijima (this conference) for the study of new types of crystal structures and the defects in known structures associated with fluctuations of stoichiometry. The image intensities may be computed using n-beam dynamical diffraction theory involving several hundred beams (Fejes, this conference). However it is still important to have a suitable approximation to provide an immediate rough estimate of contrast and an evaluation of the intuitive interpretation in terms of an amplitude object.For crystals 100 to 150Å thick containing moderately heavy atoms the phase changes of the electron wave vary by about 10 radians suggesting that the “optimum defocus” theory of amplitude contrast for thin phase objects due to Scherzer and others can not apply, although it does predict the right defocus for optimum imaging.

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Remote diagnostics of vibrations of dynamic objects by Doppler microwave sensors

Metrologiya ◽

10.32446/0132-4713.2020-3-25-42 ◽

2020 ◽

pp. 25-42

Author(s):

Dmitrii V. Khablov

Keyword(s):

Intelligent Systems ◽

Electromagnetic Waves ◽

Continuous Monitoring ◽

Phase Changes ◽

Vibration Diagnostics ◽

Remote Diagnostics ◽

Active Vibration ◽

Dynamic Objects ◽

Microwave Sensors ◽

Non Destructive

This paper describes a promising method for non-contact vibration diagnostics based on the use of Doppler microwave sensors. In this case, active irradiation of the object with electromagnetic waves and the allocation of phase changes using two-channel quadrature processing of the received reflected signal are used. The modes of further fine analysis of the resulting signal using spectral or wavelet transformations depending on the nature of the active vibration are considered. The advantages of this non-contact and remote vibration analysis method for the study of complex dynamic objects are described. The convenience of the method for machine learning and use in intelligent systems of non-destructive continuous monitoring of the state of these objects by vibration is noted.

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