Elucidating the Impact of Thermodynamic Hydrate Inhibitors and Kinetic Hydrate Inhibitors on a Complex System of Natural Gas Hydrates: Application in Flow Assurance

Abstract

To alleviate the hydrate blockage risk in oil and gas pipelines/production facilities, thermodynamic hydrate inhibitors (THIs) and kinetic hydrate inhibitors (KHIs) are the frequently used additives/chemicals. While these additives are highly effective, the impact of low dosage of THIs (under inhibited systems) and performance of KHIs at high water cut and/or high subcooling is not well understood. In this work, a high-pressure visual stirred tank reactor was employed to investigate the impact of THIs and KHIs on the kinetics of the complex hydrates of natural gas mixtures (CH4/C2H6/C3H8) and cyclopentane at high water-cut and high subcooling (∼21 °C). Various concentrations of a THI, mono-ethylene glycol (MEG) with a dosage ranging from 0.1 to 25 wt %, and multiple KHIs (polyvinylpyrrolidone (PVP k-30, PVP k-90), caprolactam, butyl glycol ether (BGE), and polyglycerin with 0.1 wt % dosage) were evaluated for hydrate formation kinetics, onset hydrate formation/nucleation temperature, and morphological changes. Gas uptake results reveal that hydrate blockage risk is higher at low MEG content (0.1 to 10 wt %) compared to the baseline, while a significant reduction in gas uptake was observed for the high MEG content trials (20–25 wt %). With 20 and 25 wt % MEG, the hydrate nucleation temperature was reduced by 10–12 °C compared to the baseline. In context to KHIs impact, 0.1 wt % BGE and caprolactam promoted the nucleation temperature and the rate of hydrate formation/gas uptake. However, PVPs not only reduced the gas uptake kinetics but also lessened the hydrate nucleation temperature by 6–8 °C compared to the baseline data. Our results may offer new insights into optimizing hydrate inhibitors dosage to diminish the risk of hydrate blockage in subsea pipelines.

Behavior of Gas Hydrate Formation in Long-Distance Pipelines for CO2 Transportation

“…To effectively prevent hydrate formation in pipelines, the injection of inhibitors is commonly employed in engineering. Injecting inhibitors is considered the most efficient and convenient method for preventing hydrate formation in long-distance pipelines . However, in practical engineering, determining the appropriate type and dosage of inhibitor is a crucial issue.…”

Enhanced Methane Hydrate Formation Kinetics in Frozen Particles of Biopolymer Solutions: Applicable to Methane Storage

“…The initial hydrate formation rate was calculated using eq and reported as a normalized rate for the first 30 min of hydrate growth (NR 30 ) Where V water is the amount of water (m 3 ) and R 30 is the hydrate growth rate (mol of methane consumed/min) calculated for the first 30 min of the hydrate growth phase, using the linear regression analysis method.…”

“…The initial hydrate formation rate was calculated using eq 9 and reported as a normalized rate for the first 30 min of hydrate growth (NR 30 ) 28 = R V NR (mol of methane/min /m of water)…”

“…In such structures, water molecules are the hosts, and gas molecules are the guests. 1 m 3 hydrate can hold up to 160–180 m 3 of gas volume under normal conditions. , It is precisely due to the property of containing a large amount of gas, hydrates are of interest in many areas besides the storage and transport of natural gas, − such as carbon dioxide capture, , mixture gas separation, seawater desalination, and others. However, one of the main problems in the deployment of hydrate-based technologies is the sluggish kinetics of hydrate formation.…”

Lightweight insulating oil-well cement filled with hollow glass microspheres and numerical simulation of its unsteady heat transfer process

“…The traditional strategy to prevent hydrate formation in a wellbore involves modifying the hydrate formation conditions by adding thermodynamic inhibitors [5][6][7]. Although this method has been widely used in marine oil and gas transportation, it has the disadvantage of requiring large quantities of inhibitors; moreover, it is expensive and results in severe pollution [8,9].…”