Where and How Are Hydrate Plugs Formed?

Sloan, Dendy; Creek, Jefferson L.; Sum, Amadeu K.

doi:10.1016/b978-1-85617-945-4.00002-9

Cited by 39 publications

(29 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…into hydrogen-bonded water cages at suitable pressure and temperature conditions (subsea pipeline conditions). 5,6 The most common industrial practice to avoid hydrate crystallization is the injection of thermodynamic hydrate inhibitors (THIs, e.g., glycols and methanol), which works while shifting the hydrate phase equilibrium conditions toward higher pressure or lower temperature. 7,8 However, the large amount of THIs (20−40 wt % with respect to the production water) is a critical concern.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2023

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%

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

et al. 2023

View full text Add to dashboard Cite

show abstract

“…Accordingly, their formation, transportability, blockage, and remediation in the main flowline, from the wellhead to the platform/gathering station, have been a mainstay for flow assurance in the oil and gas industry. 2,3 The operational mishaps associated with gas hydrates are often related to transient operations, that is, shut-in and restart of the main production system. Since most wellbores near the wellhead or above-ground vertical pipes and conduits are exposed and unprotected from the surrounding environments, they can be cooled quickly to the ambient temperature during shut-in conditions.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation to Quantify Gas Hydrate Formation during Shutdown in the Wellbore Near the Wellhead: Impact of Thermodynamic Inhibitors

2023

View full text Add to dashboard Cite

In most cases, concerns about gas hydrates in hydrocarbon production are often associated with shut-in and restart of the production system associated with the fluids in the wellhead and the main flowline. The exposure of the wellhead to cold temperatures during shutdown can cause severe hydrate formation even with stagnant fluid in the wellbore. Similar conditions may exist at the top of the gas line in flowlines for hydrate formation when gas is saturated with water. This study investigated the hydrate deposition kinetics and morphology at 10 MPa (ca. 1400 psi), with the goal of preventing severe solid hydrate formation from the vapor or supercritical phase near the wellhead or a vertical conduit exposed to cold conditions such as road overpass or river crossing during shutdown and providing operating guidelines for hydrate management by understanding the impact of volatile (methanol) and non-volatile (monethylene glycol, MEG) thermodynamic hydrate inhibitors (THIs). These results may also apply to top of line hydrate and its inhibition. It was verified that non-volatile THI is ineffective in preventing hydrate deposition near the wellhead, showing growth behavior of hydrate formation in the presence of MEG similar to that with lower pressure without inhibitors. However, volatile THI prevents hydrate deposition in a cold wellhead even though the experimental condition provides sufficient convection and water condensation. In the warm wellhead, volatile THI does not prevent hydrate formation, but it delays the growth of hydrate deposits. In the presence of volatile THI, the dissociation and reformation of hydrate deposits on the vertical wall are observed. This study provides a quantifiable method for hydrate growth in real-time and insight into better management strategies for THI usage to mitigate hydrate blockage risk near the wellhead.

show abstract

“…Methane hydrates present a prominent concern for flow assurance in the energy sector, as their growth can block the pipes and result in major safety hazards, equipment damage, financial loss, and catastrophes for the environment. 3,4 The most frequently employed hydrate inhibitors are antifreezes such as methanol and ethylene glycol. 5,6 Alcohols and glycols are categorized as thermodynamic inhibitors, which operate by shifting the hydrate forming conditions to a lower temperature and higher pressure.…”

Section: Introductionmentioning

confidence: 99%

Effects of Poly(vinylpyrrolidone) on the Dynamic Viscosity of Methane Hydrate Systems at High-Pressure Driving Forces: Investigation of Concentration, Molecular Weight, and Shear Rate

Guerra

McElligott

et al. 2022

Energy Fuels

View full text Add to dashboard Cite

The viscosity of methane hydrate slurries with poly(vinylpyrrolidone) (PVP) at 700 and 7000 ppm by weight, molecular weights of 40 000 (PVP40) and 360 000 (PVP360) Da, and shear rates of 400 and 80 s–1 were measured in a high-pressure rheometer with pressures up to 30 MPag and compared to pure water systems. The additives successfully reduced the formation of high-viscosity slurries but at low concentrations were incapable of delaying hydrate agglomeration at the late growth stage. The average relative time required for PVP40 solutions at 700 ppm to grow to 50 mPa·s was 1.9 times the water reference value but only 1.2 times to reach 200 mPa·s. Improved inhibition was observed for the higher concentration and higher molecular weight sets, where the relative times to reach 50 mPa·s were 8.2 and 2.6 times the water reference value, respectively. While the additives demonstrated antinucleation properties and suppressed crystal growth initially, they accelerated the hydrate clusters agglomeration rate and potentially weakened the hydrate mechanical properties.

show abstract

Where and How Are Hydrate Plugs Formed?

Cited by 39 publications

References 12 publications

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

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

Experimental Investigation to Quantify Gas Hydrate Formation during Shutdown in the Wellbore Near the Wellhead: Impact of Thermodynamic Inhibitors

Effects of Poly(vinylpyrrolidone) on the Dynamic Viscosity of Methane Hydrate Systems at High-Pressure Driving Forces: Investigation of Concentration, Molecular Weight, and Shear Rate

Contact Info

Product

Resources

About