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The role of fluid migration in the occurrence of shallow gas and gas hydrates in the south of the Pearl River Mouth Basin, South China Sea

Yang Jinxiu, Wang Xiujuan, Jin Jiapeng, Li Yuanping, Li Jie, Qian Jin, Shi Hesheng and Zhang Guangxu
The role of fluid migration in the occurrence of shallow gas and gas hydrates in the south of the Pearl River Mouth Basin, South China Sea
Interpretation (Tulsa) (May 2017) 5 (3): SM1-SM11

Abstract

High-amplitude anomalies (HAAs), bottom-simulating reflectors (BSRs), vertical acoustic blanking features, polygonal faults, and mass transport complexes are observed in high-resolution 3D seismic data from the south of the Pearl River Mouth Basin, South China Sea. We have focused on the role of fluid migration in the occurrence of shallow gas and gas hydrates. HAAs are interpreted to be shallow gas accumulations or gas hydrates, depending on their polarity and the presence of BSRs. Acoustic blanking features are probably caused by the presence of gas chimneys and overlying free gas due to features including chaotic and weak seismic reflections, pull-downs, and long distances of vertical extension. These gas chimneys root into the underlying late Oligocene gas reservoir. There is a close spatial relationship among the gas reservoir, gas chimneys, shallow gas accumulations, and BSRs, suggesting a genetic link. We have developed a schematic model to explain the processes of fluid migration, which supplied gas to the shallow gas accumulations and the gas hydrate system. When the gas reservoir was critically pressured, the focused fluid migration pathways may be formed or be reactivated, and gas was transported vertically along these conduits to the shallow strata. Then, there were two destinies for the migrated gas at shallow depths. One is that gas was trapped below low-permeability seals, such as mudstone or gas hydrates, forming shallow gas accumulations or free gas zones. The other one is that gas entered the gas hydrate stability zone and formed gas hydrates. In addition, this research indicates that the shallow hydrocarbon resource in this area may not be very prolific probably due to limited fluid migration.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 5
Serial Issue: 3
Title: The role of fluid migration in the occurrence of shallow gas and gas hydrates in the south of the Pearl River Mouth Basin, South China Sea
Affiliation: China University of Petroleum, Research Institute of Unconventional Oil and Gas and Renewable Energy, Qingdao, China
Pages: SM1-SM11
Published: 201705
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 57
Accession Number: 2017-074489
Categories: Applied geophysicsEconomic geology, geology of energy sources
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. chart, sects., sketch maps
N19°30'00" - N19°40'00", E115°00'00" - E115°12'00"
Secondary Affiliation: Chinese Academy of Sciences, Institute of Oceanology, CHN, ChinaChina National Offshore Oil Corporation, Shenzhen Branch, CHN, China
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201739
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