Investigation of the Flow Characteristics of Methane Hydrate Slurries with Low Flow Rates

Gas hydrate blockage in pipelines during offshore production becomes a major problem with increasing water depth. In this work, a series of experiments on gas hydrate formation in a flow loop was performed with low flow rates of 0.33, 0.66, and 0.88 m/s; the effects of the initial subcooling, flow r...

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Bibliographic Details
Published in:Energies
Main Authors: Tang, Cuiping, Zhao, Xiangyong, Li, Dongliang, He, Yong, Shen, Xiaodong, Liang, Deqing
Format: Article in Journal/Newspaper
Language:English
Published: MDPI AG 2017
Subjects:
Natural Gas
Hydrate
Flow Assurance
Slurry
Sludge
Flow Characteristics
Science & Technology
Technology
Energy & Fuels
WATER CUT SYSTEMS
GAS HYDRATE
ICE-SLURRY
CRUDE-OIL
INHIBITORS
VISCOSITY
EMULSION
LOOP
MODEL
Methane hydrate
Online Access:http://ir.giec.ac.cn/handle/344007/14017
https://doi.org/10.3390/en10010145
Description
Summary:Gas hydrate blockage in pipelines during offshore production becomes a major problem with increasing water depth. In this work, a series of experiments on gas hydrate formation in a flow loop was performed with low flow rates of 0.33, 0.66, and 0.88 m/s; the effects of the initial subcooling, flow rate, pressure, and morphology were investigated for methane hydrate formation in the flow loop. The results indicate that the differential pressure drop (Delta P) across two ends of the horizontal straight pipe increases with increasing hydrate concentration at the early stage of gas hydrate formation. When the flow rates of hydrate fluid are low, the higher the subcooling is, the faster the transition of the hydrates macrostructures. Gas hydrates can agglomerate, and sludge hydrates appear at subcoolings of 6.5 and 8.5 degrees C. The difference between the Delta P values at different flow rates is small, and there is no obvious influence of the flow rates on Delta P. Three hydrate macrostructures were observed: slurry-like, sludge-like, and their transition. When the initial pressure is 8.0 MPa, large methane hydrate blockages appear at the gas hydrate concentration of approximately 7%. Based on the gas-liquid two-phase flow model, a correlation between the gas hydrate concentration and the value of Delta P is also presented. These results can enrich the kinetic data of gas hydrate formation and agglomeration and provide guidance for oil and gas transportation in pipelines.

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