Effect of Kinetic Hydrate Inhibitor Polyvinylcaprolactam on Cyclopentane Hydrate Cohesion Forces and Growth

Wu, Reuben; Aman, Zachary M.; May, Eric F.; Kozielski, Karen; Hartley, Patrick G.; Maeda, Nobuyo; Sum, Amadeu K.

doi:10.1021/ef500265w

Cited by 25 publications

(26 citation statements)

References 22 publications

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“…26 By measuring the lateral film growth rate and applying the heat transfer-limited growth model from Mori, 21 Wu et al 25 calculated an initial film thickness in their baseline measurements that was consistent with values measured by Taylor et al 23 The presence of the KHI reduced both the growth rate and thickness of the hydrate film, suggesting the interaction of KHI with the water-oil or hydrateoil interfaces introduced additional mass transport limitations. Wu et al 27 32 proposed that the BRs were a subfraction of the resin class, in which the species interact strongly with asphaltenes resulting in co-precipitation.…”

Section: Introductionmentioning

confidence: 99%

Reduction of Clathrate Hydrate Film Growth Rate by Naturally Occurring Surface Active Components

et al. 2017

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During the production of offshore oil and gas, the cooling of hydrocarbons toward seafloor temperatures enables the formation of gas hydrates, which may restrict fluid flow and ultimately block the flowline. During the formation of a hydrate blockage, a hydrate film may grow between individual particles or between hydrate particles and the pipeline wall, respectively resulting in a higher slurry viscosity or a reduced hydraulic diameter. This hydrate film growth rate has been previously studied as a function of pressure, temperature, and hydrate guest species, but limited data are available to guide whether naturally-occurring surface active components in the oil may affect the hydrate film growth rate. In this study, we have used a micromechanical force (MMF) apparatus to quantify the film growth rate of cyclopentane hydrate at moderate subcooling. Naturally-occurring surface active species were obtained from an Australian crude oil by solvent extraction to separate out asphaltenes, binding resins, and free resins. Each crude oil fraction was then added to a chemically inert hydrocarbon phase, and the impact of the hydrate film growth rate was measured. The results illustrate that, at mass fractions below 300 ppm, the hydrate film growth rate was reduced by at least one order of magnitude with asphaltenes and free resins being the most and least effective fractions, respectively, at suppressing hydrate film growth rate. The presence of each fraction also caused an increase in the wetting angle of the water droplet on the hydrate particle surface, which suggested that these naturally-occurring components may adsorb to the hydrate particle surface. Measurements with the MMF revealed that each of the three fractions was able to reduce the hydrate particle cohesive force by two orders of magnitude.

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Section: Introductionmentioning

confidence: 99%

Reduction of Clathrate Hydrate Film Growth Rate by Naturally Occurring Surface Active Components

et al. 2017

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“…Currently, hydrate blockage has become a hot issue in flow-assurance in the petroleum industry [2] since Hammerschmidt [3] discovered hydrate blockage in gas pipelines for the first time. Controlling methods of hydrate blockage include traditional inhibition [4][5][6][7] and risk-control techniques [8][9][10][11][12]. As exploration and production is going into deeper water, the focus of flow-assurance strategies are shifting from traditional methods to risk-control techniques [2].…”

Section: Introductionmentioning

confidence: 99%

Study on the Decomposition Mechanism of Natural Gas Hydrate Particles and Its Microscopic Agglomeration Characteristics

Shi

Zhou

et al. 2018

Applied Sciences

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Research on hydrate dissociation mechanisms is critical to solving the issue of hydrate blockage and developing hydrate slurry transportation technology. Thus, in this paper, natural gas hydrate slurry decomposition experiments were investigated on a high-pressure hydrate experimental loop, which was equipped with two on-line particle analyzers: focused beam reflectance measurement (FBRM) and particle video microscope (PVM). First, it was observed from the PVM that different hydrate particles did not dissociate at the same time in the system, which indicated that the probability of hydrate particle dissociation depended on the particle’s shape and size. Meanwhile, data from FBRM presented a periodic oscillating trend of the particle/droplet numbers and chord length during the hydrate slurry dissociation, which further demonstrated these micro hydrate particles/droplets were in a dynamic coupling process of breakage and agglomeration under the action of flow shear during the hydrate slurry dissociation. Then, the influences of flow rate, pressure, water-cut, and additive dosage on the particles chord length distribution during the hydrate decomposition were summarized. Moreover, two kinds of particle chord length treatment methods (the average un-weighted and squared-weighted) were utilized to analyze these data onto hydrate particles’ chord length distribution. Finally, based on the above experimental data analysis, some important conclusions were obtained. The agglomeration of particles/droplets was easier under low flow rate during hydrate slurry dissociation, while high flow rate could restrain agglomeration effectively. The particle/droplet agglomerating trend and plug probability went up with the water-cut in the process of hydrate slurry decomposition. In addition, anti-agglomerates (AA) greatly prohibited those micro-particles/droplets from agglomeration during decomposition, resulting in relatively stable mean and square weighting chord length curves.

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“…In general, lower molecular weight gases such as CH 4 and CO 2 require higher pressures and lower temperatures to form stable hydrates (CH 4 forms a stable hydrate at 4 °C when the pressure reaches 3.9 MPa), whereas hydrocarbons such as propane require less severe conditions. Cyclopentane forms hydrates at ambient pressures and is often used as a model material. ,,− The dissociation temperature of cyclopentane hydrates formed at atmospheric pressure was measured previously, and it is ≈7.5 °C. ,− , …”

Section: Introductionmentioning

confidence: 99%

“…Hydrate inhibition chemicals have also been a focus. They generally fall into two classes: the traditional thermodynamic inhibitors (THIs), such as methanol and monoethylene glycol, and low-dosage hydrate inhibitors (LDHIs), such as kinetic inhibitors (KHIs) and anti-agglomerants (AA). , The objective of the thermodynamic inhibitors is to change the hydrate “envelope” in order that the pressures and temperatures of the system become outside of it . The KHIs delay the crystallization time to avoid blockage whereas the AAs make hydrate particles remain dispersed to avoid agglomerates …”

Section: Introductionmentioning

confidence: 99%

Growth Kinetics and Mechanics of Hydrate Films by Interfacial Rheology

2016

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A new approach to study and understand the kinetics and mechanical properties of hydrates by interfacial rheology is presented. This is made possible using a "double wall ring" interfacial rheology cell that has been designed to provide the necessary temperature control. Cyclopentane and water are used to form hydrates, and this model system forms these structures at ambient pressures. Different temperature and water/hydrocarbon contact protocols are explored. Of particular interest is the importance of first contacting the hydrocarbon against ice crystals in order to initiate hydrate formation. Indeed, this is found to be the case, even though the hydrates may be created at temperatures above the melting point of ice. Once hydrates completely populate the hydrocarbon/water interface, strain sweeps of the interfacial elastic and viscous moduli are conducted to interrogate the mechanical response and fragility of the hydrate films. The dependence on temperature, Tf, by the kinetics of formation and the mechanical properties is reported, and the cyclopentane hydrate dissociation temperature was found to be between 6 and 7 °C. The formation time (measured from the moment when cyclopentane first contacts ice crystals) as well as the elastic modulus and the yield strain increase as Tf increases.

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Effect of Kinetic Hydrate Inhibitor Polyvinylcaprolactam on Cyclopentane Hydrate Cohesion Forces and Growth

Cited by 25 publications

References 22 publications

Reduction of Clathrate Hydrate Film Growth Rate by Naturally Occurring Surface Active Components

Reduction of Clathrate Hydrate Film Growth Rate by Naturally Occurring Surface Active Components

Study on the Decomposition Mechanism of Natural Gas Hydrate Particles and Its Microscopic Agglomeration Characteristics

Growth Kinetics and Mechanics of Hydrate Films by Interfacial Rheology

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