Wax Deposition From Emulsion-water in Stratified Flow

Quan, Qing; Wang, W.; Wang, P.; Duan, Jimiao; Yang, Juheng; Yao, Haiyuan; Gong, Junbo

doi:10.1080/10916466.2015.1007381

Cited by 5 publications

(3 citation statements)

References 5 publications

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“…Therefore, it is significant to study the coupling characteristics of hydrate formation and wax precipitation in W/O emulsions. There are many independent studies on hydrate formation − and wax precipitation − in W/O emulsions. Limited studies have been reported about the interaction mechanism of hydrate formation and wax precipitation, and few recognized conclusions can be obtained.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Investigation of the Interaction between Hydrate Formation and Wax Precipitation in Water-in-Oil Emulsions

2018

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The study of the interaction between hydrate formation and wax precipitation in water-in-oil (W/O) emulsions is of great significance for the security of development in deep-water waxy oil and gas fields. Experiments of natural gas hydrate formation in W/O emulsions containing wax crystals were performed in a high-pressure autoclave. The macro-parametric data, including pressure, temperature, hydrate induction time, hydrate growth amount and rate, were compared and analyzed. Results indicated that the stage behavior of hydrate formation process was not affected by the precipitated wax crystals in W/O emulsions. The mass transfer resistance of hydrate nucleation was enhanced in waxy W/O emulsions. Hence, the hydrate induction time was prolonged and could be estimated by a semiempirical crystallization model developed based on the Freundlich adsorption isotherm theory. Meanwhile, the precipitated wax crystals in W/O emulsions affected the porosity of the hydrate shell, leading to a decrease in the average hydrate growth rate, but the total hydrate growth amount increased compared to the emulsified systems without wax crystals. The effect of hydrate formation and dissociation on the wax precipitation was studied, combined with the data analysis obtained from the polarizing microscopic observation. More wax crystals precipitated in the systems after hydrate dissociation compared to the systems without hydrate formation. The fractal box dimension of the precipitated wax crystals was relatively larger affected by hydrate formation and dissociation, implying that the structure of precipitated wax crystals was more intricate.

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Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Investigation of the Interaction between Hydrate Formation and Wax Precipitation in Water-in-Oil Emulsions

2018

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“…Wax deposition in pipeline transportation systems reduces the effective flowing area of the pipeline, reduces the transmission capacity of the pipeline and can even lead to plugging accidents in serious cases. Wax deposition in subsea oil pipelines is a significant flow assurance problem [6,7].…”

Section: Introductionmentioning

confidence: 99%

Experimental Measurements of Wax Precipitation Using a Modified Method of Simultaneous Centrifugation and High-Temperature Gas Chromatography

Liu

Duan

et al. 2021

Energies

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Wax precipitation and deposition are serious flow assurance problems. Wax precipitation is investigated simultaneously using centrifugation and high-temperature gas chromatography (C-HTGC) to obtain the amount and component distribution of precipitated wax in artificial waxy oil and diesel at different temperatures. However, the conventional C-HTGC method gives upper measurements of the amount of precipitated wax, as it ignores wax dissolved in crude oil in the centrifugal cake. A modified C-HTGC method was developed to obtain the precipitated solid fraction of crude oil, based on the mass balances of the non-crystallized fraction of the centrifuged cake. The weight, percent and carbon number distribution of precipitated solid wax crystals at different temperatures of artificial oil and 0# diesel were obtained. It was found that wax precipitation characteristics are affected by many factors, including the carbon number distribution of the oil, the sensitivity of alkane crystallization to temperature and the temperature of the waxy oil solution. The average carbon number of alkanes in precipitated wax crystals decreases with the decrease in temperature. The distribution of alkanes in solid wax crystals is roughly the same as that in 0# diesel but slightly heavier than in diesel. Alkanes with high carbon numbers precipitate simultaneously with those with low carbon numbers.

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“…The oil exploited from the Bohai Sea and South China Sea in China is mostly waxy [7]. The intense heat transfer between oil-gas pipeline and the subsea environment in the deep sea (4°C) aggravates the wax deposit.…”

Section: Introductionmentioning

confidence: 99%

A model of wax deposition under oil-gas two-phase stratified flow in horizontal pipe

Duan

Liu

et al. 2018

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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A model of wax deposition based on molecular diffusion mechanism, for oil-gas two-phase stratified pipe flow is developed. In the model, unidirectional fully developed flow analyses of momentum, heat and mass transfer are presented. And, a cube cage model is used to describe the wax deposit structure considering the effect of oil flow shear on the deposit. Calculation of wax deposit is compared well with a flow loop experiment. In particular, the model could give the wax deposit forming a crescent shape at the cross section of pipe, which is observed in different experiments. Furthermore, the cause of forming a crescent shape is revealed, which is indicated by the non-uniform circumferential distribution of mass flux for wax deposition along the pipe wall wetted by the oil. The mass flux from oil bulk flow to the oil-deposit interface is closely related to three parameters, diffusivity at oil-deposit interface, the temperature gradient at the oil-deposit interface at different time, and the slope of the wax solubility curve at oil-deposit interface temperature.

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Wax Deposition From Emulsion-water in Stratified Flow

Cited by 5 publications

References 5 publications

Experimental and Theoretical Investigation of the Interaction between Hydrate Formation and Wax Precipitation in Water-in-Oil Emulsions

Experimental and Theoretical Investigation of the Interaction between Hydrate Formation and Wax Precipitation in Water-in-Oil Emulsions

Experimental Measurements of Wax Precipitation Using a Modified Method of Simultaneous Centrifugation and High-Temperature Gas Chromatography

A model of wax deposition under oil-gas two-phase stratified flow in horizontal pipe

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