New insights into the effect of polyvinylpyrrolidone (PVP) concentration on methane hydrate growth. 2. Liquid phase methane mole fraction

Posteraro, Dany; Ivall, Jason; Marić, Milan; Servio, Phillip

doi:10.1016/j.ces.2014.12.008

Cited by 45 publications

(32 citation statements)

References 33 publications

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“…Kinetic hydrate inhibitors (KHIs) have been used since the mid 1990s to prevent gas hydrate blockages in oil and gas production flow lines. − The potential formation of these ice-like solids of clathrate small hydrocarbons constitutes one of the most significant flow assurance issues for offshore fields. − KHIs are formulations of one or more structurally specific water-soluble polymers in solvents and other synergists. KHIs can affect both the gas hydrate nucleation and crystal growth processes, delaying the build-up of gas hydrates for a length of time depending on the driving force (chemical potential) of the system. , KHIs have been shown to both increase the nucleation work required to form critical size nuclei and increase the effective number of sites where nucleation could occur . The driving force of the system is often described in terms of subcooling, but other factors including the absolute pressure must be taken into account. − There is evidence that KHIs can give total inhibition for an indefinite period up to a certain driving force …”

Section: Introductionmentioning

confidence: 99%

Non-Amide Polymers as Kinetic Hydrate Inhibitors─Maleic Acid/Alkyl Acrylate Copolymers and the Effect of pH on Performance

2021

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Kinetic hydrate inhibitors (KHIs) have been used for over 25 years to prevent gas hydrate formation in oil and gas production flow lines. The main component in KHI formulations is a water-soluble polymer with many amphiphilic groups, usually made up of amide groups and adjacent hydrophobic groups with 3–6 carbon atoms. KHI polymers are one of the most expensive oilfield production chemicals. Therefore, methods to make cheaper but effective KHIs could improve the range of applications. Continuing earlier work from our group with maleic-based polymers, here, we explore maleic acid/alkyl acrylate copolymers as potential low-cost KHIs. Performance experiments were conducted under high pressure with a structure II-forming natural gas mixture in steel rocking cells using the slow (1 °C/h) constant cooling test method. Under typical pipeline conditions of pH (4–6), the performance of the maleic acid/alkyl acrylate copolymers (alkyl = iso-propyl, iso-butyl, n-butyl, tetrahydrofurfuryl, and cyclohexyl) was poor. However, good performance was observed at very high pH (13–14) due to the thermodynamic effect from added salts in the aqueous phase and the removal of CO2 from the gas phase. A methyl maleamide/n-butyl acrylate copolymer gave very poor performance, giving evidence that direct bonding of the hydrophilic amide and C4 hydrophobic groups is needed for good KHI performance. Reaction of the maleic anhydride (MA) units in MA/alkyl acrylate 1:1 copolymers with dibutylaminopropylamine or dibutylaminoethanol gave polymers with good KHI performance, with MA/tetrahydrofurfuryl methacrylate being the best. Oxidation of the pendant dibutylamino groups to amine oxide groups improved the performance further, better than poly(N-vinyl caprolactam).

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Section: Introductionmentioning

confidence: 99%

Non-Amide Polymers as Kinetic Hydrate Inhibitors─Maleic Acid/Alkyl Acrylate Copolymers and the Effect of pH on Performance

2021

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“…While micelles still form in solution, most of the KHI chains are not in that structure. At much higher concentrations of KHI in solution, Posteraro had seen that further increasing concentrations of KHI (PVP) in solution did not substantially increase hydrate inhibition …”

Section: Resultsmentioning

confidence: 99%

Poly(styrene/pentafluorostyrene)‐block‐poly(vinyl alcohol/vinylpyrrolidone) amphiphilic block copolymers for kinetic gas hydrate inhibitors: Synthesis, micellization behavior, and methane hydrate kinetic inhibition

Rajput

Colantuoni

Bayahya

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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Amphiphilic block copolymers of short poly(styrene) (PS) or poly(2,3,4,5,6‐pentafluorostyrene) (PPFS) segments with comparatively longer poly(vinyl acetate) or poly(vinylpyrrolidone) (PVP) segments are synthesized using a 2‐cyanopropan‐2‐yl N‐methyl‐N‐(pyridin‐4‐yl)dithiocarbamate switchable reversible addition–fragmentation chain transfer (RAFT) agent toward application as kinetic gas hydrate inhibitors (KHIs). Polymerization conditions are optimized to provide water‐soluble block copolymers by first polymerizing more activated monomers such as S and PFS to form a defined macro chain‐transfer agent (linear degree of polymerization with conversion, comparatively low dispersity) followed by chain extensions with less activated monomers VAc or VP by switching to the deprotonated form of the RAFT agent. The critical micelle concentrations of these amphiphilic block copolymers (after VAc unit hydrolysis to vinyl alcohol units) are measured using zeta surface potential measurements to estimate physical behavior once mixed with the hydrates. A PS‐poly(vinyl alcohol) block copolymer improved inhibition to 49% compared to the pure methane–water system with no KHIs. This inhibition was further reduced by 27% by substituting the PS with a more hydrophobic PPFS. A block copolymer of PS–PVP exhibited 20% greater inhibition than the PVP homopolymer and substituting PS with a more hydrophobic PPFS resulted in a 35% further decreased in methane KHI. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2445–2457, 56, 2445–2457

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“…Experimental studies were conducted by Posteraro et al 68 and Ivall et al, 69 providing results in favor of the surface adsorption mechanism. Furthermore, Hutter et al 70 measured the inhibitor surface adsorption by neutron scattering experiments.…”

Section: Khis Based On Cyclic Amidesmentioning

confidence: 99%

Review of Kinetic Hydrate Inhibitors Based on Cyclic Amides and Effect of Various Synergists

Singh

Suri

2021

Energy Fuels

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This Review presents a comprehensive literature review of an important class of kinetic hydrate inhibitors (KHIs) that is based on cyclic amides (lactams). The major aspects of the KHIs, such as their synthesis, inhibition mechanism, toxicity, biodegradability, performance, and cloud point, are thoroughly discussed. Data for 70 KHIs made of homo/co/terpolymers from 330 experiments are collected and evaluated for performance. The effects of the inhibitor concentration, molecular weight, monomer ratio of the co/terpolymers, and 35 different synergist chemicals on various KHIs are also studied. In conclusion, the top 10 KHIs with the highest performances that had a cloud point above 70 °C are presented. The copolymer (1:1) N-vinylpyrrolidone/N-vinyl-caprolactam (VP/VCap) is found to have the highest induction time (IT) of 13 to 14 h at 0.25 wt % and at a cooling rate of 1 °C/h. Some KHIs like Inhibex BIO-800 and poly(N-vinyl azacyclooctanone) (PVACO) also have a very high ITs (17 and 13.5 h, respectively) at 0.25 wt % and at a cooling rate of 1 °C/h, but they have low cloud points (<25 °C). Guanidinium salts (n-Bu6GuanCl/n-Bu6GuanBr) and a phosphonium salt, (n-Pe)4PBr, are found to be the best synergists for the cyclic-amide-based KHIs. When used at 0.15 to 0.30 wt % along with the KHIs, they further increase the IT by 3–5 h.

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New insights into the effect of polyvinylpyrrolidone (PVP) concentration on methane hydrate growth. 2. Liquid phase methane mole fraction

Cited by 45 publications

References 33 publications

Non-Amide Polymers as Kinetic Hydrate Inhibitors─Maleic Acid/Alkyl Acrylate Copolymers and the Effect of pH on Performance

Non-Amide Polymers as Kinetic Hydrate Inhibitors─Maleic Acid/Alkyl Acrylate Copolymers and the Effect of pH on Performance

Poly(styrene/pentafluorostyrene)‐block‐poly(vinyl alcohol/vinylpyrrolidone) amphiphilic block copolymers for kinetic gas hydrate inhibitors: Synthesis, micellization behavior, and methane hydrate kinetic inhibition

Review of Kinetic Hydrate Inhibitors Based on Cyclic Amides and Effect of Various Synergists

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