Wax Deposition of Water-in-crude Oil Emulsion in a Flow-loop Apparatus

Quan, Qing; Wang, W.; Wang, P.; Zhou, Yuanxin; Gong, Jing

doi:10.1080/10916466.2014.999944

Cited by 9 publications

(3 citation statements)

References 9 publications

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“…The variations of deposition rates with time in a Nigerian crude oil emulsion were recorded by Adeyanjua and Oyekunle by using a flow loop apparatus, in which the emulsified oil generated a thicker deposit during the period of experiment from 9 to 19 h. The authors attributed the thickness increase to the water droplets trapped in the deposits. Moreover, a similar trend that the deposit thickness initially decreased with the rise in water cut but increased thereafter was also observed by Mansourpoor et al and Quan et al, who claimed that the gelation of emulsions was responsible for the increased deposit thickness. Wang et al explored that the gelation behavior comprising emulsified water, waxy crystals, and aggregation of crude oil significantly affected the wax deposition when the two oil–water phases flowed in the pipe.…”

Section: Introductionsupporting

confidence: 83%

Experimental Study on the Effect of Wax Crystal-Water Droplet Aggregations on Wax Deposition of Water-in-Oil Emulsions

Wang

et al. 2023

Energy Fuels

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Wax deposition in waxy crude oil emulsions remains a flow assurance challenge in offshore production. Wax molecular diffusion driven by the positive temperature gradient from the liquid to the pipe wall has been widely studied and regarded as the primary wax deposition mechanism; however, a considerable wax deposit of emulsions at a zero-temperature difference was detected, in which condition molecular diffusion is not likely to occur, suggesting there were other mechanisms that contribute to wax deposition. In this work, the wax deposition mechanism of water-in-oil emulsions at a zero-temperature difference was explored by a cold finger apparatus regarding the role of wax crystals and water droplets on wax deposition. Through microscopy observation and component measurement of deposits, the wax deposition mechanism, namely, wax crystal-water droplet aggregation formation and adhesion behavior, was proposed. During wax deposition, wax crystals in the emulsion interacted with water droplets, organizing the basic structure of aggregation. The liquid oil phase was entrapped at the inner space of the aggregation and entrained by the wax crystal-water droplet structure to generate a wax deposit. The formation of wax crystal-water droplet aggregations depends on the experimental temperature, where a larger size of aggregations that formed at a lower temperature preferred to yield a thicker deposit under the same stirring speed, while for the same temperature operation conditions, the medium and low speed promoted the adhesion behavior of the aggregations to the cold finger resulting in an increase in deposits; however, the high stirring condition sloughed off the formed deposits, reducing the deposit mass. The findings denote that the presence of wax crystal-water droplet aggregations in emulsion should be considered when describing the wax deposition process at low temperatures.

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Section: Introductionsupporting

confidence: 83%

Experimental Study on the Effect of Wax Crystal-Water Droplet Aggregations on Wax Deposition of Water-in-Oil Emulsions

Wang

et al. 2023

Energy Fuels

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“…A similar trend in the effect of water on wax deposition rate was also observed by Kasumu and Mehrotra . Wang et al and Quan et al observed nonmonotonic variation in the deposition rate with increasing water content. , The investigators explained the nonmonotonic variation in the wax deposition rate based on a combination of a diffusion and a gelation mechanism. Wang et al further advanced the understanding of the gelling deposition mechanism on wax deposition and proposed an algebraic model to calculate deposition rate based on this mechanism …”

Section: Introductionsupporting

confidence: 72%

Entrapment of Water Droplets in Wax Deposits from Water-in-Oil Dispersion and Its Impact on Deposit Build-up

2016

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Wax deposition from water-in-oil emulsion/dispersion can entrap water droplets in the resulting paraffin deposits. This entrapment of water droplets can lead to a significant decrease in the yield stress of the deposits, which can cause the deposit to slough-off during wax deposition. This investigation presents the most comprehensive characterization of the entrapment of water droplets by deposit formation with cold finger and flow loop wax deposition experiments. NMR techniques were implemented to characterize the droplet size of the bulk and deposit in order to reveal the relationship between the droplet size of the bulk and the water content of the deposit. Furthermore, it is demonstrated that incorporation of droplets in the deposit lowers the yield stress of the deposit and causes the deposit to slough-off during pipe flow. Knowledge of such effects of the water phase on wax deposition is beyond conventional analysis based on heat and mass transfers and is expected to provide additional insights to the design of water–oil two phase transport pipelines.

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“…With the exploration of off-shore oil fields and the construction of the subsea pipelines, wax deposition of multiphase flow becomes an unavoidable problem for the production of the petroleum industry. − The buildup of wax deposition in the inner surface of subsea pipelines causes the reduction of cross-area, which is available for fluid transportation, and an increase in the risk of blockage of process equipment . Wax molecular diffusion is regarded as the mechanism for wax deposition. − In addition, many research studies in recent years have focused on the investigation of water appearance in wax deposition as the presence of water in deposition changes the properties and rheology of deposition, , which further influences the heat and mass transfer during deposition as well as the thickness of deposition. ,, …”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Entrapped Water Droplets in Wax Deposition from Water-in-Oil Emulsion Considering Wax Crystals Adsorption at the Oil–Water Interface

Wang

et al. 2019

Energy Fuels

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The presence of water in wax deposition from water-in-oil emulsion for petroleum transportation in pipelines has received much attention in recent years. This study investigated the formation of wax deposition with water droplets, considering interfacial adsorption by wax crystals. The prepared 20 vol % water-in-oil emulsion was used for the wax deposition experiment with an analysis of deposition mass/thickness and water volume fraction in deposition, determining that the water content in deposition during the whole deposition duration was constant and equaled to the water content in emulsion. Moreover, a polarizing microscope was employed to observe the microstructure of wax deposition, revealing that some water droplets were covered with wax crystals due to interfacial adsorption, while some droplets were enclosed by the network of wax crystals. Depending on these findings, two kinds of entrapment of water droplets in deposition were proposed. One contained the formation and growth of a crystal network accompanied with these wax-covered water droplets themselves; another one indicated that water droplets were surrounded by a crystal network, resulting in the movement of these droplets being limited and therefore the droplets settling in deposition. Furthermore, a comparison of the distribution of water droplets in deposition using a microscope and that in emulsion by focused-beam reflectance measurement was presented. It was observed that these small droplets were more likely to be incorporated into deposition in contrast with these large ones. The largest size measured for an entrapped water droplet was 115 μm, which was in accordance with the previous research claiming that the general diameter of water droplets incorporated into deposition was no more than ∼100 μm. Interfacial adsorption of wax crystals provides an additional insight to investigate water droplets in wax deposition.

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Wax Deposition of Water-in-crude Oil Emulsion in a Flow-loop Apparatus

Cited by 9 publications

References 9 publications

Experimental Study on the Effect of Wax Crystal-Water Droplet Aggregations on Wax Deposition of Water-in-Oil Emulsions

Experimental Study on the Effect of Wax Crystal-Water Droplet Aggregations on Wax Deposition of Water-in-Oil Emulsions

Entrapment of Water Droplets in Wax Deposits from Water-in-Oil Dispersion and Its Impact on Deposit Build-up

Experimental Investigation of Entrapped Water Droplets in Wax Deposition from Water-in-Oil Emulsion Considering Wax Crystals Adsorption at the Oil–Water Interface

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