Review of gas hydrate anti-agglomerant screening techniques

Salmin, Davi Costa; Estanga, Douglas; Koh, Carolyn A.

doi:10.1016/j.fuel.2021.122862

Cited by 35 publications

(17 citation statements)

References 94 publications

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“…The head groups in commercial AAs are often quaternary ammonium or phosphonium bonded to one or more butyl groups. Thus, the THF hydrate results help explain the improved effect of AAs in brines containing calcium as the calcium appear as to help slow hydrate crystal growth, a key step in the “hydrate-philic” AA mechanism . Four of the five additives investigated have active cationic groups, quaternary ammonium, phosphonium, and guanidinium.…”

Section: Resultsmentioning

confidence: 94%

Effect of Divalent Cations and Other Ions on the Tetrahydrofuran Crystal Inhibition of Quaternary Ammonium Salts─Relevance to the Efficiency of Gas Hydrate Quaternary Anti-agglomerants

Kelland,

Rønning

2023

ACS Omega

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Gas hydrate anti-agglomerants (AAs) are a class of low-dosage hydrate inhibitor that are used to prevent plugging of gas hydrates in oil and condensate upstream flow lines. Industrial AAs are mostly cationic surfactants which are “hydrate-philic”, i.e., they are designed to interact with and modify gas hydrate crystal growth. Tetrahydrofuran (THF) hydrate crystal growth studies have been used for many years to determine useful functional groups to incorporate into AA surfactants. In particular, quaternary ammonium and phosphonium salts with optimized alkyl groups show good THF crystal growth inhibition, which is a key property for AAs. AAs are often screened and tested in model brines containing sodium chloride despite the produced water containing various divalent cations. Recent studies have shown that AAs performed better when tested in brines containing both sodium and calcium ions rather than just sodium ions. Here, we present THF hydrate crystal growth studies on quaternary ammonium and phosphonium salts and other related molecules including guanidinium salts and amine oxides. Tests were carried out with a variety of cations including sodium, calcium, magnesium, and lithium at identical pre-determined subcooling, in order to investigate the effect of the ion size and charge density on the crystal growth inhibition. We also investigate the effect of using the more polarizable iodide ions compared to chloride ions. Our results show that crystal growth inhibition in solutions with calcium ions is somewhat greater than that with sodium ions, in agreement with past studies on the effect of AA performance with mono- and divalent cations. However, the variation does not seem to be primarily related to the charge density and polarizing ability of the cations. This study therefore provides evidence that AAs should be tested in brines containing all the ions present in the produced water and not just sodium chloride brine.

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Section: Resultsmentioning

confidence: 94%

Effect of Divalent Cations and Other Ions on the Tetrahydrofuran Crystal Inhibition of Quaternary Ammonium Salts─Relevance to the Efficiency of Gas Hydrate Quaternary Anti-agglomerants

Kelland,

Rønning

2023

ACS Omega

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“…There are also LDHIs that, when added in the water, prevent the agglomeration of gas hydrate crystals. [ 28 ] Thus, instead of a hydrate plug forming to eventually block the flow of hydrocarbon fluids, the hydrates are in the form of dispersed hydrate particles and flow along with the fluids as depicted in the schematic in Figure 4.…”

Section: Survey Of Gas Hydrate Technologies and Trl Classificationmentioning

confidence: 99%

Technology readiness level of gas hydrate technologies

Englezos

2022

Can J Chem Eng

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Gas or clathrate hydrates are non-stoichiometric crystalline materials known primarily for the operational and safety problems they pose during hydrocarbon processing as well as a potential source of unconventional natural gas.Gas hydrates also have a variety of other applications, mostly representing opportunities for technology development such as gas separations and seawater desalination. This dual nature of gas hydrates is best represented by the two faces of a Janus particle. Although the research on the various gas

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“…AAs are molecules that prevent the hydrate crystals from sticking together and forming larger compounds. Several polymers and surfactants are examples of AAs. − AAs suspend hydrate crystals in solution, resulting in dispersing hydrates as small particles and preventing the accumulation of hydrate. Although the AAs do not prevent hydrate formation, they prevent hydrate blockage in the pipelines …”

Section: Introductionmentioning

confidence: 99%

Impacts of Triethylene Glycol and Polyvinyl Caprolactam on Dissociation Conditions and Complete Inhibition Region of Methane Hydrate

Hamidpour,

Javanmardi,

Rasoolzadeh

et al. 2023

Energy Fuels

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In nearly all cases, the strength of low-dosage hydrate inhibitors (LDHIs) is evaluated by a comparison of the induction time. Since hydrate nucleation has a stochastic nature, measurement and correlation of the induction time are troublous and nonrepeatable. Thus, the development of new techniques to make the performance of LDHIs predictable and repeatable is necessary. This work aimed at employing the crystal growth inhibition (CGI) approach as a well-known repeatable technique to determine the complete inhibition region (CIR) of methane hydrate in the simultaneous attendance of triethylene glycol (TEG) as thermodynamic hydrate inhibitor (THI) and polyvinyl caprolactam (PVCap-7k) as LDHI. To determine the CIR, the hydrate dissociation measurements were carried out. For this purpose, two aqueous solutions of (0.46 wt % PVCap-7k + 15.00 wt % TEG), and (1.00 wt % PVCap-7k + 15.00 wt % TEG) were prepared. In the previous studies, the dissociation conditions of methane hydrate in the attendance of 0.10, 0.25, and 0.49 wt % of PVCap-7k were experimentally measured. To compare the inhibition impacts of TEG + PVCap-7k with PVCap-7k, the dissociation conditions of methane hydrate in the attendance of (1.00 wt % PVCap-7k) were also experimentally measured. Moreover, for thermodynamic modeling, a package including the van der Waals−Platteeuw (vdW-P) model for the hydrate phase, the Peng−Robinson (PR) equation of state (EoS) for the vapor-gas phase, and the Flory−Huggins (FH) model for the calculation of the water activity in an aqueous liquid phase was applied. It is concluded that the combined utilization of TEG and PVCap-7k results in a thermodynamic promotion impact on the methane hydrate. This is due to the strong thermodynamic promotion effect of PVCap that overcomes the thermodynamic inhibition impact of TEG. From the kinetic viewpoint, the combined utilization of TEG and PVCap-7k leads to a wide CIR (between 9 and 11.5 °C) which means a strong kinetic inhibition performance.

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Review of gas hydrate anti-agglomerant screening techniques

Cited by 35 publications

References 94 publications

Effect of Divalent Cations and Other Ions on the Tetrahydrofuran Crystal Inhibition of Quaternary Ammonium Salts─Relevance to the Efficiency of Gas Hydrate Quaternary Anti-agglomerants

Effect of Divalent Cations and Other Ions on the Tetrahydrofuran Crystal Inhibition of Quaternary Ammonium Salts─Relevance to the Efficiency of Gas Hydrate Quaternary Anti-agglomerants

Technology readiness level of gas hydrate technologies

Impacts of Triethylene Glycol and Polyvinyl Caprolactam on Dissociation Conditions and Complete Inhibition Region of Methane Hydrate

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