Evaluation of clayed silt properties on the behavior of hydrate production in South China Sea

ABSTRACT: Gas hydrate is one kind of potential energy resources that is buried under deep seafloor or frozen areas. The first trial offshore production from the silty reservoir was conducted in the South China Sea by the China Geological Survey (CGS). During this test, there were many unique charact...

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Bibliographic Details
Published in:China Geology
Main Authors: Qiang Chen, Gao-wei Hu, Neng-you Wu, Chang-ling Liu, Qing-guo Meng, Cheng-feng Li, Jian-ye Sun, Yan-long Li
Format: Article in Journal/Newspaper
Language:English
Published: KeAi Communications Co., Ltd. 2020
Subjects:
Natural gas hydrate
Reservoir physical properties
Hydrate structure
Thermal-physical properties
Irreducible water
NGH exploration trial engineering
Engineering (General). Civil engineering (General)
TA1-2040
Geology
QE1-996.5
Methane hydrate
Online Access:https://doi.org/10.31035/cg2020050
https://doaj.org/article/be916a190c084b4d98badb6357928bd3
Description
Summary:ABSTRACT: Gas hydrate is one kind of potential energy resources that is buried under deep seafloor or frozen areas. The first trial offshore production from the silty reservoir was conducted in the South China Sea by the China Geological Survey (CGS). During this test, there were many unique characteristics different from the sand reservoir, which was believed to be related to the clayed silt physical properties. In this paper, simulation experiments, facilities analysis, and theoretical calculation were used to confirm the hydrate structure, reservoir thermo-physical property, and bond water movement rule. And the behavior of how they affected production efficiency was analyzed. The results showed that: It was reasonable to use the structure I rather than structure II methane hydrate phase equilibrium data to make the production plan; the dissociation heat absorbed by hydrate was large enough to cause hydrate self-protection or reformation depend on the reservoir thermal transfer and gas supply; clayed silt got better thermal conductivity compared to coarse grain, but poor thermal convection especially with hydrate; clayed silt sediment was easy to bond water, but the irreducible water can be exchanged to free water under high production pressure, and the most obvious pressure range of water increment was 1.9–4.9 MPa.

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