Experimental Study on CH4 Hydrate Dissociation by the Injection of Hot Water, Brine, and Ionic Liquids

Thermal stimulation is an important method to promote gas production and to avoid secondary hydrate formation during hydrate exploitation, but low thermal efficiency hinders its application. In this work, hydrate dissociation was carried out in synthesized hydrate-bearing sediments with 30% hydrate...

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Bibliographic Details
Published in:Journal of marine science and engineering 2023-04, Vol.11 (4), p.713
Main Authors: Wu, Siting, Zhou, Xuebing, Lu, Jingsheng, Liang, Deqing, Li, Dongliang
Format: Article
Language:English
Subjects:
Accuracy
Brines
Chloride
Chlorides
Dissociation
Efficiency
Energy
Exploitation
Gas production
Heat
Hot water
hydrate
Hydrates
Injection
Intake temperature
ionic liquid
Ionic liquids
Ions
Liquids
Methane
Methane hydrates
Natural gas
Oil and gas production
saline
Saturation
sediment
Sediments
Sodium chloride
Stability
Steel pipes
thermal stimulation
Thermodynamic efficiency
Water flooding
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Summary:Thermal stimulation is an important method to promote gas production and to avoid secondary hydrate formation during hydrate exploitation, but low thermal efficiency hinders its application. In this work, hydrate dissociation was carried out in synthesized hydrate-bearing sediments with 30% hydrate saturation at 6.9 MPa and 9 °C. Ionic liquids, such as 1-butyl-3-methylimidazolium chloride (BMIM-Cl) and tetramethylammonium chloride (TMACl), were injected as heat carriers, and the promotion effects were compared with the injection of hot water and brine. The results showed that the injection of brine and ionic liquids can produce higher thermal efficiencies compared to hot water. Thermodynamic hydrate inhibitors, such as NaCl, BMIM-Cl, and TMACl, were found to impair the stability of CH4 hydrate, which was conducive to hydrate dissociation. By increasing the NaCl concentration from 3.5 to 20 wt%, the thermal efficiency increased from 37.6 to 44.0%, but the thermal efficiencies experienced a fall as the concentration of either BMIM-Cl or TMACl grew from 10 to 20 wt%. In addition, increasing the injection temperature from 30 to 50 °C was found to bring a sharp decrease in thermal efficiency, which was unfavorable for the economics of gas production. Suitable running conditions for ionic liquids injection should control the concentration of ionic liquids under 10 wt% and the injection temperature should be around 10 °C, which is conducive to exerting the weakening effect of ionic liquids on hydrate stability.
ISSN:2077-1312
2077-1312
DOI:10.3390/jmse11040713