Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, Shenhu Area, South China Sea
ABSTRACT: Evaluating velocity-porosity relationships of hydrate-bearing marine sediments is essential for characterizing natural gas hydrates below seafloor as either a potential energy resource or geohazards risks. Four sites had cored using pressure and non-pressure methods during the gas hydrates...
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2022
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ftdoajarticles:oai:doaj.org/article:34b04f751c944463a2b39877027bed53 2023-05-15T17:12:07+02:00 Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, Shenhu Area, South China Sea Lin Lin Jun Cao Jin Qian Jiu-jing Shang Wei Zhang Jin-gan Lu Jin-qiang Liang 2022-04-01T00:00:00Z https://doi.org/10.31035/cg2022006 https://doaj.org/article/34b04f751c944463a2b39877027bed53 EN eng KeAi Communications Co., Ltd. http://www.sciencedirect.com/science/article/pii/S2096519222001161 https://doaj.org/toc/2096-5192 2096-5192 doi:10.31035/cg2022006 https://doaj.org/article/34b04f751c944463a2b39877027bed53 China Geology, Vol 5, Iss 2, Pp 267-275 (2022) Natural gas hydrates (NGHs) Methane hydrate P-wave velocity Porosity Saturation Pressure-core Engineering (General). Civil engineering (General) TA1-2040 Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.31035/cg2022006 2023-02-12T01:31:21Z ABSTRACT: Evaluating velocity-porosity relationships of hydrate-bearing marine sediments is essential for characterizing natural gas hydrates below seafloor as either a potential energy resource or geohazards risks. Four sites had cored using pressure and non-pressure methods during the gas hydrates drilling project (GMGS4) expedition at Shenhu Area, north slope of the South China Sea. Sediments were cored above, below, and through the gas-hydrate-bearing zone guided with logging-while-drilling analysis results. Gamma density and P-wave velocity were measured in each pressure core before subsampling. Methane hydrates volumes in total 62 samples were calculated from the moles of excess methane collected during depressurization experiments. The concentration of methane hydrates ranged from 0.3% to 32.3%. The concentrations of pore fluid (25.44% to 68.82%) and sediments (23.63% to 54.28%) were calculated from the gamma density. The regression models of P-wave velocity were derived and compared with a global empirical equation derived from shallow, unconsolidated sediments data. The results were close to the global trend when the fluid concentration is larger than the critical porosity. It is concluded that the dominant factor of P-wave velocity in hydrate-bearing marine sediments is the presence of the hydrate. Methane hydrates can reduce the fluid concentration by discharging the pore fluid and occupying the original pore space of sediments after its formation.©2022 China Geology Editorial Office. Article in Journal/Newspaper Methane hydrate Directory of Open Access Journals: DOAJ Articles China Geology 5 2 1 9 |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
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language |
English |
topic |
Natural gas hydrates (NGHs) Methane hydrate P-wave velocity Porosity Saturation Pressure-core Engineering (General). Civil engineering (General) TA1-2040 Geology QE1-996.5 |
spellingShingle |
Natural gas hydrates (NGHs) Methane hydrate P-wave velocity Porosity Saturation Pressure-core Engineering (General). Civil engineering (General) TA1-2040 Geology QE1-996.5 Lin Lin Jun Cao Jin Qian Jiu-jing Shang Wei Zhang Jin-gan Lu Jin-qiang Liang Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, Shenhu Area, South China Sea |
topic_facet |
Natural gas hydrates (NGHs) Methane hydrate P-wave velocity Porosity Saturation Pressure-core Engineering (General). Civil engineering (General) TA1-2040 Geology QE1-996.5 |
description |
ABSTRACT: Evaluating velocity-porosity relationships of hydrate-bearing marine sediments is essential for characterizing natural gas hydrates below seafloor as either a potential energy resource or geohazards risks. Four sites had cored using pressure and non-pressure methods during the gas hydrates drilling project (GMGS4) expedition at Shenhu Area, north slope of the South China Sea. Sediments were cored above, below, and through the gas-hydrate-bearing zone guided with logging-while-drilling analysis results. Gamma density and P-wave velocity were measured in each pressure core before subsampling. Methane hydrates volumes in total 62 samples were calculated from the moles of excess methane collected during depressurization experiments. The concentration of methane hydrates ranged from 0.3% to 32.3%. The concentrations of pore fluid (25.44% to 68.82%) and sediments (23.63% to 54.28%) were calculated from the gamma density. The regression models of P-wave velocity were derived and compared with a global empirical equation derived from shallow, unconsolidated sediments data. The results were close to the global trend when the fluid concentration is larger than the critical porosity. It is concluded that the dominant factor of P-wave velocity in hydrate-bearing marine sediments is the presence of the hydrate. Methane hydrates can reduce the fluid concentration by discharging the pore fluid and occupying the original pore space of sediments after its formation.©2022 China Geology Editorial Office. |
format |
Article in Journal/Newspaper |
author |
Lin Lin Jun Cao Jin Qian Jiu-jing Shang Wei Zhang Jin-gan Lu Jin-qiang Liang |
author_facet |
Lin Lin Jun Cao Jin Qian Jiu-jing Shang Wei Zhang Jin-gan Lu Jin-qiang Liang |
author_sort |
Lin Lin |
title |
Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, Shenhu Area, South China Sea |
title_short |
Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, Shenhu Area, South China Sea |
title_full |
Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, Shenhu Area, South China Sea |
title_fullStr |
Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, Shenhu Area, South China Sea |
title_full_unstemmed |
Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, Shenhu Area, South China Sea |
title_sort |
velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores, shenhu area, south china sea |
publisher |
KeAi Communications Co., Ltd. |
publishDate |
2022 |
url |
https://doi.org/10.31035/cg2022006 https://doaj.org/article/34b04f751c944463a2b39877027bed53 |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
China Geology, Vol 5, Iss 2, Pp 267-275 (2022) |
op_relation |
http://www.sciencedirect.com/science/article/pii/S2096519222001161 https://doaj.org/toc/2096-5192 2096-5192 doi:10.31035/cg2022006 https://doaj.org/article/34b04f751c944463a2b39877027bed53 |
op_doi |
https://doi.org/10.31035/cg2022006 |
container_title |
China Geology |
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5 |
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1 |
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9 |
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1766068889977880576 |