Study of Agglomeration Characteristics of Hydrate Particles in Oil/Gas Pipelines

Wang, Wuchang; Li, Yuxing; Haihong, Liu; Peng, Zhao

doi:10.1155/2014/457050

Cited by 16 publications

(14 citation statements)

References 10 publications

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“…27,33 Insight into the properties and mechanisms of the agglomeration can be provided by the cohesive forces. 34,35 From previous studies, 30,36,37 the capillary liquid bridge (CLB) theory was shown to be the most appropriate model to explain the hydrate particle cohesive force phenomenon. This model describes the liquid bridge present between particles (as shown in Figure 2), which is shown in eq 1:…”

Section: ■ Introductionmentioning

confidence: 99%

Structural Effects of Gas Hydrate Antiagglomerant Molecules on Interfacial Interparticle Force Interactions

Monteiro

et al. 2021

Langmuir

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Gas hydrate interparticle cohesive forces are important to determine the hydrate crystal particle agglomeration behavior and subsequent hydrate slurry transport that is critical to preventing potentially catastrophic consequences of subsea oil/gas pipeline blockages. A unique high-pressure micromechanical force apparatus has been employed to investigate the effect of the molecular structure of industrially relevant hydrate antiagglomerant (AA) inhibitors on gas hydrate crystal interparticle interactions. Four AA molecules with known detailed structures [quaternary ammonium salts with two long tails (R1) and one short tail (R2)] in which the R1 has 12 carbon (C12) and 8 carbon (C8) and saturated (C–C) versus unsaturated (CC) bonding are used in this work to investigate their interfacial activity to suppress hydrate crystal interparticle interactions in the presence of two liquid hydrocarbons (n-dodecane and n-heptane). All AAs were able to reduce the interparticle cohesive force from the baseline (23.5 ± 2.5 mN m–1), but AA-C12 shows superior performance in both liquid hydrocarbons compared to the other AAs. The interfacial measurements indicate that the AA with an R1 longer alkyl chain length can provide a denser barrier, and the AA molecules may have higher packing density when the AA R1 alkyl tail length is comparable to that of the liquid hydrocarbon chain on the gas hydrate crystal surface. Increasing the salinity can promote the effectiveness of an AA molecule and can also eliminate the effect of longer particle contact times, which typically increases the interparticle cohesive force. This work reports the first experimental investigation of high-performance known molecular structure AAs under industrially relevant conditions, showing that these molecules can reduce the interfacial tension and increase the gas hydrate–water contact angle, thereby minimizing the gas hydrate interparticle interactions. The structure–performance relation reported in this work can be used to help in the design of improved AA inhibitor molecules that will be critical to industrial hydrate crystal slurry transport.

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Section: ■ Introductionmentioning

confidence: 99%

Structural Effects of Gas Hydrate Antiagglomerant Molecules on Interfacial Interparticle Force Interactions

Monteiro

et al. 2021

Langmuir

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“…Insights into AA mechanisms of action have been obtained by measuring cohesive and adhesive forces. 35,36 After overcoming initial difficulties, the micromechanical force (MMF) apparatus has shown great practical and fundamental potential because it measures directly hydrate interparticle cohesive forces. 23,37,38 For example, Dieker et al 39 and Aman et al 40 investigated the effect of carboxylic acids and crude oils on cyclopentane (CyC5) hydrate particle interactions.…”

Section: ■ Introductionmentioning

confidence: 99%

Correlating Antiagglomerant Performance with Gas Hydrate Cohesion

Phan

Stamatakis

Koh

et al. 2021

ACS Appl. Mater. Interfaces

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Although inhibiting hydrate formation in hydrocarbon− water systems is paramount in preventing pipe blockage in hydrocarbon transport systems, the molecular mechanisms responsible for antiagglomerant (AA) performance are not completely understood. To better understand why macroscopic performance is affected by apparently small changes in the AA molecular structure, we perform molecular dynamics simulations. We quantify the cohesion energy between two gas hydrate nanoparticles dispersed in liquid hydrocarbons in the presence of different AAs, and we achieve excellent agreement against experimental data obtained at high pressure using the micromechanical force apparatus. This suggests that the proposed simulation approach could provide a screening method for predicting, in silico, the performance of new molecules designed to manage hydrates in flow assurance. Our results suggest that entropy and free energy of solvation of AAs, combined in some cases with the molecular orientation at hydrate−oil interfaces, are descriptors that could be used to predict performance, should the results presented here be reproduced for other systems as well. These insights could help speed up the design of new AAs and guide future experiments.

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“…The issue of flow assurance has posed sufficient hazard for the oil and gas industry to employ dedicated flow assurance engineers [1]. forces [56]. The following sections describe the findings from literature relating these forces to agglomeration.…”

Section: Agglomerationmentioning

confidence: 99%

“…Hydrate particles in a suspension of oil and water will agglomerate, and according to many sources, the most accurate representations of agglomeration forces are influenced heavily by the capillary bridge force [1,56,[62][63][64]. Figure 8 presents the proposed capillary bridge geometry linking two nearby particles of radius R 1 and R 2 separated by a distance S; the two fluids of densities ρ 1 and ρ 2 form a surface with interfacial energy γ LL ; the bridge forms an internal contact angle θ p and an embracing angle α with the particle at an immersion depth of d.…”

Section: Capillary Actionmentioning

confidence: 99%

“…However, from a kinetic point of view, greater subcooling limits interparticle interaction through increased viscosities of the oil phase. And from an interfacial point of view, greater subcooling depletes liquid water which is necessary for the capillary action that dominates.2.3.3 Other ForcesAside from capillary action, Wang et al identified several other factors that affect the attractive forces driving hydrate particle agglomeration, though the majority of them are insignificant[56]. Gravity can influence particles of different densities in the vertical displacements.…”

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confidence: 99%

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Surfactant Effect on Hydrate Crystallization Mechanism

Dann

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SURFACTANT EFFECT ON HYDRATE CRYSTALLIZATION MECHANISM by Kevin Dann Gas hydrates pose economic and environmental risks to the oil and gas industry when plug formation occurs in pipelines. A novel approach using interfacial rheology was applied to understand cyclopentane clathrate hydrate formation in the presence of nonionic surfactant to achieve hydrate inhibition at low percent weight compared to thermodynamic inhibitors. The hydrate-inhibiting performance of low (CMC) concentrations of Span 20, Span 80, Pluronic L31, and Tween 65 at 2 • C on a manually nucleated 2 µL droplet showed a morphological shift in crystallization from planar shell growth to conical growth for growth rates below 0.20 mm 2 /min. Monitoring the internal pressure of a droplet undergoing planar hydrate crystallization provided a strong correlation (up to R = −0.989) of decreasing interfacial tension to the shrinking area of the water-cyclopentane interface. Results from the high-concentration batch of surfactants indicated that while initial hydrate growth is largely suppressed, the final stage of droplet conversion becomes rapid. This effect was observed following droplet collapse from the combination of large conical growths and low interfacial tensions. The low-concentration batch of surfactants saw rapid growth rates that diminished once hydrate shell coverage was completed. The most effective surfactant was the high-concentration Tween 65 (0.15 g/100mL), which slowed hydrate growth to 0.068 mm 2 /min, nearly an order of magnitude slower than that found for pure water at 0.590 mm 2 /min. High molecular weight (1845 g/mol) and HLB (10.5) close to 10 contribute to a large energy of desorption at an interface and are believed to be the sources of Tween 65's hydrate-inhibiting properties.

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Study of Agglomeration Characteristics of Hydrate Particles in Oil/Gas Pipelines

Cited by 16 publications

References 10 publications

Structural Effects of Gas Hydrate Antiagglomerant Molecules on Interfacial Interparticle Force Interactions

Structural Effects of Gas Hydrate Antiagglomerant Molecules on Interfacial Interparticle Force Interactions

Correlating Antiagglomerant Performance with Gas Hydrate Cohesion

Surfactant Effect on Hydrate Crystallization Mechanism

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