Characteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China

Abstract The Changjiang (Yangtze) is one of the largest rivers in the world. It formed a huge incised valley at its mouth during the Last Glacial Maximum; the incised-valley fill, approximately 80–110 m thick, supplies an important foundation for the generation of shallow biogenic-gas reservoirs. Tw...

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Autores principales:	Xia Zhang, Chun-Ming Lin
Formato:	article
Lenguaje:	EN
Publicado:	KeAi Communications Co., Ltd. 2017
Materias:	Biogenic gas Formation mechanism Late Quaternary Modern Changjiang delta Eastern China Science Q Petrology QE420-499
Acceso en línea:	https://doaj.org/article/c5129eb4c4e94e649bab0ab280cb24c2
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spelling	oai:doaj.org-article:c5129eb4c4e94e649bab0ab280cb24c22021-12-02T02:14:34ZCharacteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China10.1007/s12182-017-0157-21672-51071995-8226https://doaj.org/article/c5129eb4c4e94e649bab0ab280cb24c22017-04-01T00:00:00Zhttp://link.springer.com/article/10.1007/s12182-017-0157-2https://doaj.org/toc/1672-5107https://doaj.org/toc/1995-8226Abstract The Changjiang (Yangtze) is one of the largest rivers in the world. It formed a huge incised valley at its mouth during the Last Glacial Maximum; the incised-valley fill, approximately 80–110 m thick, supplies an important foundation for the generation of shallow biogenic-gas reservoirs. Two cores and 13 cone penetration tests were used to elaborate the characteristics, formation mechanism, and distribution of the shallow biogenic-gas reservoirs in the study area. The natural gas is mainly composed of CH4 (generally >95%) with a δ13CCH4 and δ13CCO2 of −75.8 to −67.7‰ and −34.5 to −6.6‰, respectively, and a δDCH4 of −215 to −185‰, indicating a biogenic origin by the carbon dioxide reduction pathway. Commercial biogenic gas occurs primarily in the sand bodies of fluvial-channel, floodplain, and paleo-estuary facies with a burial depth of 50–80 m. Gas sources as well as cap beds are gray to yellowish-gray mud of floodplain, paleo-estuary, and offshore shallow marine facies. The organic matter in gas sources is dominated by immature type III kerogen (gas prone). The difference in permeability (about 4–6 orders of magnitude) between cap beds and reservoirs makes the cap beds effectively prevent the upward escape of gas in the reservoirs. This formation mechanism is consistent with that for the shallow biogenic gas in the late Quaternary Qiantang River incised valley to the south. Therefore, this study should provide further insight into understanding the formation and distribution of shallow biogenic gas in other similar postglacial incised-valley systems.Xia ZhangChun-Ming LinKeAi Communications Co., Ltd.articleBiogenic gasFormation mechanismLate QuaternaryModern Changjiang deltaEastern ChinaScienceQPetrologyQE420-499ENPetroleum Science, Vol 14, Iss 2, Pp 261-275 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Biogenic gas Formation mechanism Late Quaternary Modern Changjiang delta Eastern China Science Q Petrology QE420-499
spellingShingle	Biogenic gas Formation mechanism Late Quaternary Modern Changjiang delta Eastern China Science Q Petrology QE420-499 Xia Zhang Chun-Ming Lin Characteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China
description	Abstract The Changjiang (Yangtze) is one of the largest rivers in the world. It formed a huge incised valley at its mouth during the Last Glacial Maximum; the incised-valley fill, approximately 80–110 m thick, supplies an important foundation for the generation of shallow biogenic-gas reservoirs. Two cores and 13 cone penetration tests were used to elaborate the characteristics, formation mechanism, and distribution of the shallow biogenic-gas reservoirs in the study area. The natural gas is mainly composed of CH4 (generally >95%) with a δ13CCH4 and δ13CCO2 of −75.8 to −67.7‰ and −34.5 to −6.6‰, respectively, and a δDCH4 of −215 to −185‰, indicating a biogenic origin by the carbon dioxide reduction pathway. Commercial biogenic gas occurs primarily in the sand bodies of fluvial-channel, floodplain, and paleo-estuary facies with a burial depth of 50–80 m. Gas sources as well as cap beds are gray to yellowish-gray mud of floodplain, paleo-estuary, and offshore shallow marine facies. The organic matter in gas sources is dominated by immature type III kerogen (gas prone). The difference in permeability (about 4–6 orders of magnitude) between cap beds and reservoirs makes the cap beds effectively prevent the upward escape of gas in the reservoirs. This formation mechanism is consistent with that for the shallow biogenic gas in the late Quaternary Qiantang River incised valley to the south. Therefore, this study should provide further insight into understanding the formation and distribution of shallow biogenic gas in other similar postglacial incised-valley systems.
format	article
author	Xia Zhang Chun-Ming Lin
author_facet	Xia Zhang Chun-Ming Lin
author_sort	Xia Zhang
title	Characteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China
title_short	Characteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China
title_full	Characteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China
title_fullStr	Characteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China
title_full_unstemmed	Characteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China
title_sort	characteristics and accumulation model of the late quaternary shallow biogenic gas in the modern changjiang delta area, eastern china
publisher	KeAi Communications Co., Ltd.
publishDate	2017
url	https://doaj.org/article/c5129eb4c4e94e649bab0ab280cb24c2
work_keys_str_mv	AT xiazhang characteristicsandaccumulationmodelofthelatequaternaryshallowbiogenicgasinthemodernchangjiangdeltaareaeasternchina AT chunminglin characteristicsandaccumulationmodelofthelatequaternaryshallowbiogenicgasinthemodernchangjiangdeltaareaeasternchina
_version_	1718402619068645376

Characteristics and accumulation model of the late Quaternary shallow biogenic gas in the modern Changjiang delta area, eastern China

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