Abstract
Natural gas hydrate is a clean and high-efficient energy resource, and more than 90% of its reserves are contained in fine-grained (typically clayey silts) sediment. In this work, for the first time, the micro-scale imaging is performed to explore hydrate phase transition, morphology evolution and fundamental characteristics (mineral compositions, pore structures and seepage capacity) in clayey silt sediments. The results indicate that clayey silts formation properties strongly depend on dominant minerals component in the sediments. The clay-rich clayey silt possesses more microcapillary interstice with smaller permeability than that in quartz-rich sediment. Hydrates generally occur as microfracture-filling (veins) and grain-displacing (nodulus) in sand-rich clayey silt. While they occur in the form of fracture-filling (vein) and foraminifera-filling in clay-rich clayey silt sediments. Biological fossils (especially foraminifera) provides potential space for
hydrate aggregates. But hydrate formed inside it depends on the structures of fossils, the mineral components and pore structure of surrounding matrix. The hysteresis between hydrate formation and decomposition found to be more significant in clary-rich clayey silt sediment than quartz-rich sediment. And this hysteresis inside foraminifera is much more serious compared with that in matrix. In addition, dispersed pore-filling hydrates forms during decomposition, which has adverse effect on continuous gas production.
hydrate aggregates. But hydrate formed inside it depends on the structures of fossils, the mineral components and pore structure of surrounding matrix. The hysteresis between hydrate formation and decomposition found to be more significant in clary-rich clayey silt sediment than quartz-rich sediment. And this hysteresis inside foraminifera is much more serious compared with that in matrix. In addition, dispersed pore-filling hydrates forms during decomposition, which has adverse effect on continuous gas production.
Original language | English |
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Article number | 127303 |
Number of pages | 18 |
Journal | Energy |
Volume | 274 |
Early online date | 27 Mar 2023 |
DOIs | |
Publication status | Published - 1 Jul 2023 |
Bibliographical note
The authors are grateful to the National Natural Science Foundation of China, China [51991365]; China Geological Survey Project, China [DD20211350]; Guangdong Major Project of Basic and Applied Basic Research, China [2020B0301030003]; Key Program of Marine Economy Development (Six Marine Industries) of Special Foundation of Department of Natural Resources of Guangdong Province, China [2021]56.Data Availability Statement
Data will be made available on request.Keywords
- Clayey silt
- Hydrate phase transition
- Micro-scale properties
- Micro-scale imaging