Experimental Study of Single-Phase and Two-Phase Water-in-Crude-Oil Dispersed Flow Wax Deposition in a Mini Pilot-Scale Flow Loop

Panacharoensawad, Ekarit; Sarica, Cem

doi:10.1021/ef400275h

Cited by 51 publications

(96 citation statements)

References 22 publications

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“…Figure 7 also shows that the water content of several deposit samples was close to 0 vol %, which confirms the observations by Kasumu and Mehrotra 22 and Panacharoensawad and Sarica. 29 That is, the water content of the deposit may not be related to the deposition process; instead, it might represent "wetness" of the deposit surface or physical attachment of water droplets to the deposit surface and/or entrapment or occlusion of water droplets within the deposit. This observation suggests the importance of measuring the water content of the deposit and expressing the deposit mass on a water-free basis.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Solids Deposition from Wax–Solvent–Water “Waxy” Mixtures Using a Cold Finger Apparatus

Kasumu

Mehrotra

2015

Energy Fuels

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The solids deposition from one-phase and two-phase waxy mixtures (comprising a multicomponent paraffinic wax dissolved in a multicomponent solvent, and water) was studied using a cold finger experimental apparatus. The deposition experiments were performed with a 10 mass % wax solution, containing 0, 10, 20, and 30 vol % water, with two different rates of agitation, and for nine different deposition times ranging from 30 s to 24 h. The water content of the deposit was found to be not related to the water content of the waxy mixture. The short-duration experiments showed the deposition process to be very fast, with more than half of the deposition process completed in 30 s. Following a rapid rate of deposition initially, the deposit mass was observed to increase slowly to reach steady state at about 12 h. The deposit mass decreased with an increase in the agitation speed. The deposition data were modeled satisfactorily with a steady-state heat-transfer model and an unsteady-state model based on the moving boundary problem formulation. The results confirmed the liquid−deposit interface temperature to be equal to the wax appearance temperature (WAT) of the wax solution throughout the deposition process, i.e., for all deposition times. The results of this study provide further confirmation that the solids deposition process can be described adequately with an approach based solely on heat-transfer considerations. ■ INTRODUCTIONThe precipitation and deposition of solids are of significant importance in the production, transportation, and processing of "waxy" or paraffinic crude oils because wax deposition can damage oil reservoir formations and wells and cause blockage of pipelines and process equipment. Solids deposition in pipelines and process equipment causes an increase in pressure drop, an increase in pumping power requirement, and/or a decrease in efficiency. Challenges associated with solids deposition are more severe in cold environments, especially in subsea conditions, where seabed temperatures can be as low as 4°C. 1 With increasing prevalence of deep-water−oil recovery, 2 crude oil is transported over longer distances with an increase in exposure to low temperatures. Such solids deposition problems are expected to become worse and so will the control and remediation costs associated with them.Waxes are mixtures of long-chain hydrocarbons with carbon numbers ranging from 18 to 65. 3 Waxes occur in significant proportions in paraffinic crude oils. These waxes are less soluble in the crude oil at lower temperatures and tend to crystallize and deposit on cooler surfaces. The temperature at which the first wax crystals start to appear in the crude oil during cooling is known to as the wax appearance temperature (WAT) or the cloud point temperature (CPT). It is pointed out that the wax disappearance temperature (WDT, measured while heating a sample) has been shown to provide a better representation of the true solid−liquid phase transformation temperature or the liquidus temperature. 4 Although somewhat higher ...

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Solids Deposition from Wax–Solvent–Water “Waxy” Mixtures Using a Cold Finger Apparatus

Kasumu

Mehrotra

2015

Energy Fuels

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“…[150] The presence of water in two-phase flows, as either water-in-oil or oil-in-water blend, has been reported to have inconclusive effects on wax deposition. While many studies have reported a decrease in wax deposition with increasing water fraction, [115,[150][151][152][153][154][155] others have reported an increase in wax deposition with increasing water fraction, [156,157] or no significant change due to the presence of water. [55,105] Clearly, more studies are needed to establish a conclusive effect of the presence of water on wax deposition.…”

Section: Water Droplets and Emulsionmentioning

confidence: 99%

A review of heat‐transfer mechanism for solid deposition from “waxy” or paraffinic mixtures

et al. 2020

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Summarized in this review are a large number of experimental and modelling studies for advancing the heat-transfer-based mechanism for solid deposition from "waxy" or paraffinic oils and mixtures. This comprehensive heat-transfer approach is entirely different from a more popular molecular-diffusion mechanism. It has evolved from numerous publications, over three decades, which explored topics related to thermodynamic, rheological, crystallization, solid deposition, and shutdown and deposit-aging behaviour of prepared multicomponent paraffinic mixtures of varying compositions to simulate "waxy" crude oils. These investigations covered a wide range of compositions, temperatures, and cooling rates-under static, sheared, laminar and turbulent conditions-in both the hot and cold flow regimes. The heat-transfer mechanism for wax deposition is based on (partial) freezing or liquid-to-solid phase transformation process, for which steady-state and unsteady-state mathematical models have been developed and validated with extensive laboratory data. Furthermore, a shear-induced deformation model for the deposit aging phenomenon has been developed and validated; it is based on a partial release of the liquid phase from the incipient gel, thereby causing an enrichment of heavier alkanes and a corresponding depletion of lighter alkanes in the deposit. A successful analogy with the ice deposition process has confirmed the wax deposition process to be also controlled by heat transfer, without involving any other mechanism for wax deposition. All of these previous studies confirm that wax deposition is predominantly a thermally driven process. K E Y W O R D S aging, cold flow, heat transfer, solid deposition, waxy crude oil 1 | INTRODUCTION Crude oils are complex mixtures of hydrocarbons, including high molar mass alkanes or paraffins, which are referred to as waxes. Waxes contain carbon numbers ranging from 18-65. [1] Crude oils that contain a significant proportion of high molecular weight paraffins or waxes are referred to as paraffinic or "waxy" crude oils. Waxes tend to crystallize and deposit on cooler surfaces because of their decreased solubility in the crude oil at lower temperatures. The highest temperature at which the first crystals start to appear, upon cooling of a "waxy" crude oil, is called the wax appearance temperature (WAT), which is also referred to as the cloud point temperature (CPT). The precipitation and deposition of solids are of significant importance in the production,

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“…The mass‐based technique requires pigging the wax deposit and residual oil after each test using a pig (Figure ). Equations and were used to calculate the wax deposit thickness assuming uniform wax deposit . It should be noted that for this method, the test must be stopped at each time point to collect the deposit from the test section.…”

Section: Experimental Programmentioning

confidence: 99%

Investigation of inhibitors efficacy in wax deposition mitigation using a laboratory scale flow loop

Chi

Sarica

2016

AIChE Journal

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Statistically reliable wax inhibition experimental data was obtained by utilizing the newly built laboratory scale flow loop. The comb-shaped inhibitors are found more effective in decreasing the thickness compared to the linear inhibitor under the same conditions. Moreover, this becomes more predominant as the chain length of inhibitors increases. Interestingly, even though all the inhibitors decreased the deposit thickness, the wax content increased significantly. Besides, the longer chain length (PI-B) of the inhibitor results in a higher wax content. Since the combination of growth and aging influenced by the presence of inhibitor significantly, paraffin inhibition efficiency (PIE) based on the wax mass was proposed to quantitatively assess the inhibitors. Based on the PIE, PI-B, and PI-C have more inhibition efficiency than PI-A. Therefore, when selecting wax inhibitor, one should be aware about the strength of the deposit gel in addition to the reduction of the deposit mass. Fogler HS. The strength of paraffin gels formed under static and flow conditions. Chem Eng Sci. 2005;60(13):3587-3598. 44. Bello OO, Fasesan SO, Teodoriu C, Reinicke KM. An evaluation of the performance of selected wax inhibitors on paraffin deposition of Nigerian crude oils.

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Experimental Study of Single-Phase and Two-Phase Water-in-Crude-Oil Dispersed Flow Wax Deposition in a Mini Pilot-Scale Flow Loop

Cited by 51 publications

References 22 publications

Solids Deposition from Wax–Solvent–Water “Waxy” Mixtures Using a Cold Finger Apparatus

Solids Deposition from Wax–Solvent–Water “Waxy” Mixtures Using a Cold Finger Apparatus

A review of heat‐transfer mechanism for solid deposition from “waxy” or paraffinic mixtures

Investigation of inhibitors efficacy in wax deposition mitigation using a laboratory scale flow loop

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