Representative Dynamic Accumulation of Hydrate-Bearing Sediments in Gas Chimney System since 30 Kyr BP in the QiongDongNan Area, Northern South China Sea

A stratigraphic complex composed of mass transport deposits (MTDs), where the gas occurrence allows for the formation of a gas chimney and pipe structure, is identified based on seismic interpretation in the QiongDongNan area of the northern South China Sea. During the Fifth Gas Hydrate Drilling Exp...

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Bibliographic Details
Published in:Journal of Marine Science and Engineering
Main Authors: Jinan Guan, Menghe Wang, Wei Zhang, Lihua Wan, Matthias Haeckel, Qi Wu
Format: Article in Journal/Newspaper
Language:English
Published: MDPI AG 2024
Subjects:
QiongDongNan slope area
methane hydrate-bearing sediments
gas chimney
mass transport deposit
evolution dynamics
fracturing criterion
Naval architecture. Shipbuilding. Marine engineering
VM1-989
Oceanography
GC1-1581
Methane hydrate
Online Access:https://doi.org/10.3390/jmse12050834
https://doaj.org/article/ec784434fac949489e9eb8ed01f0e8f6
Description
Summary:A stratigraphic complex composed of mass transport deposits (MTDs), where the gas occurrence allows for the formation of a gas chimney and pipe structure, is identified based on seismic interpretation in the QiongDongNan area of the northern South China Sea. During the Fifth Gas Hydrate Drilling Expedition of the Guangzhou Marine Geological Survey, this type of complex morphology that has close interaction with local gas hydrate (GH) distribution was eventually confirmed. A flow-reaction model is built to explore the spatial–temporal matching evolution process of massive GH reservoirs since 30 kyr before the present (BP). Five time snapshots, including 30, 20, 10, and 5 kyr BP, as well as the present, have been selected to exhibit key strata-evolving information. The results of in situ tensile estimation imply fracturing emergence occurs mostly at 5 kyr BP. Six other environmental scenarios and three cases of paleo-hydrate existence have been compared. The results almost coincide with field GH distribution below the bottom MTD from drilling reports, and state layer fracturing behaviors always feed and probably propagate in shallow sediments. It can be concluded that this complex system with 10% pre-existing hydrates results in the exact distribution and occurrence in local fine-grained silty clay layers adjacent to upper MTDs.

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