Experimental Investigation of the Rheology and Crystal Morphology of Model Waxy Oils under Gelling Conditions

Marinho, Thiago O.; Oliveira, Márcia; Nele, Márcio

doi:10.1021/acs.energyfuels.9b01972

Cited by 12 publications

(12 citation statements)

References 70 publications

(155 reference statements)

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“…Crude oil is a complex mixture of hydrocarbons consisting of paraffins, naphthenes, aromatic, asphaltenes, resins, etc. Among these compounds, the long-chain paraffins are mainly responsible for various flow assurance issues, such as deposition and gelation of wax, during pipeline transportation of waxy crude oil at subsea conditions. , The paraffins are soluble in the crude oil at high reservoir temperatures (∼70–150 °C) and pressures (∼8–15 kPa). , Crude oil behaves like a Newtonian fluid at these reservoir conditions . The temperature of crude oil falls below the wax appearance temperature (WAT) during transportation at subsea conditions.…”

Section: Introductionmentioning

confidence: 99%

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New Method for Gelation Temperature Measurement without Disturbing the Crystal Network

Shinde

Kumar

2021

Ind. Eng. Chem. Res.

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The present study proposes a new nonoscillatory nonrotary (NONR) method to measure gelation temperature based on a temperature-dependent normal force. A variation in the normal force signal is observed due to the combined effect of volume shrinkage and wax crystal network. The sample retains fluidity above the gelation temperature, in the absence of a gel network. The proposed method shows good repeatability for a model waxy oil and real crude oils. The results of the NONR method are consistent with the results from earlier methods. Gelation temperature measurement using the NONR method does not require gel movement. However, all of the existing rheological methods use either shear stress or shear rate, which participates in the gelation process. The gelation temperatures of 15% macrocrystalline wax in the dodecane sample measured using constant shear stress, constant shear rate, oscillatory, and NONR methods are 26.6, 27.5, 26.8, and 27.0 °C, respectively.

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Section: Introductionmentioning

confidence: 99%

“…1,2 The paraffins are soluble in the crude oil at high reservoir temperatures (∼70− 150 °C) and pressures (∼8−15 kPa). 3,4 Crude oil behaves like a Newtonian fluid at these reservoir conditions. 5 The temperature of crude oil falls below the wax appearance temperature (WAT) during transportation at subsea conditions.…”

Section: Introductionmentioning

confidence: 99%

New Method for Gelation Temperature Measurement without Disturbing the Crystal Network

Shinde

Kumar

2021

Ind. Eng. Chem. Res.

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“…The same trends observed for the yield stress results apply for G 0 LVR , i.e., (i) when a geometry with a smooth moving part is employed, G 0 LVR presents the lowest value; (ii) an intermediate value is achieved when a grooved moving part is used with a smooth stationary part; and (iii) the highest G 0 LVR is obtained for the all-grooved geometry. There are several investigations pointing to the correlation between yield stress and storage modulus for drilling fluids [48], waxy crude oil [49,50], and model waxy oil [30,51]. In the particular case of waxy gels, both properties arise from the same phenomenon, i.e., oil gelation [52]; thus, it is reasonable to assume a strong correlation of both properties, as described in our previous study [30,51].…”

Section: Postcooling Rheometric Measurementsmentioning

confidence: 76%

“…There are several investigations pointing to the correlation between yield stress and storage modulus for drilling fluids [48], waxy crude oil [49,50], and model waxy oil [30,51]. In the particular case of waxy gels, both properties arise from the same phenomenon, i.e., oil gelation [52]; thus, it is reasonable to assume a strong correlation of both properties, as described in our previous study [30,51].…”

Section: Postcooling Rheometric Measurementsmentioning

confidence: 76%

Apparent wall slip effects on rheometric measurements of waxy gels

Marinho

Marchesini

Oliveira

et al. 2021

Journal of Rheology

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The effects of apparent wall slip on rheometric measurements of waxy gels are quantified for gels consisting of a macrocrystalline wax added in mineral oil in concentrations of 3.0 and 7.5 wt. %. The waxy gels are formed in situ in a stress-controlled rheometer, and rheological properties are then obtained. Seven different geometry configurations, including parallel plates, concentric cylinders, and vane, are employed. The surface roughness of the different geometries and wax crystals size are assessed to provide insight into the apparent wall slip phenomenon. In the presence of smooth surfaces, a decrease in approximately 80% in the measured yield stress value is observed in oscillatory tests, regardless of system composition. In addition, the storage modulus measurements are substantially different when obtained from smooth or grooved geometries. In creep experiments, the yield stress measurements decrease by 68%. As expected, apparent wall slip markedly affects the shape of the flow curves obtained, causing the appearance of kinks for smooth Couette geometry. Apparent slip velocities are calculated in the regime just above the yield stress, and it is found that for low concentrations apparent slip increases with concentration and decreases with the ratio between the shear stress and dynamic yield stress. The gathered results also demonstrate that the reproducibility of rheological measurements is improved by using geometries with grooved parts. By quantifying the effects of apparent wall slip on rheological measurements of waxy gels for different geometries, this work can provide useful information for the design of pipelines and oil transportation processes.

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“…Yu et al 30 studied the effect of EVA doped with Fe 3 O 4 magnetic spherical nanoparticles on the morphology of wax crystals and the flow behavior of Daqing crude oil through polarization optical microscopy and rheological tests. Marinho et al 31 investigated the influence of cooling rate and other six experimental variables on the yield stress of gelled waxy oils. They further assessed the wax crystal morphology by polarized light microscopy (PLM).…”

Section: Introductionmentioning

confidence: 99%

Effect of Initial Cooling Temperature on Structural Behaviors of Gelled Waxy Crude Oil and Microscopic Mechanism Investigation

et al. 2020

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A comprehensive investigation of the effect of initial cooling temperature on the structural behaviors of gelled waxy crude oil is conducted, including the "temperature-dependent viscoelasticity behaviors", "time-dependent viscoelasticity behaviors", "time-dependent deformation behaviors", "structural decomposition behaviors", "thixotropic behavior", and "microstructure manifestation". Two different structural behaviors are exhibited with contrary rigid and brittle structural characters, structural regeneration performances, and cooling rate and oscillation frequency responses. The strongest elastic-dominated viscoelasticity and thixotropic behaviors occur at the initial cooling temperature near wax dissolution temperature (WDT). With increasing initial cooling temperature, a noticeable decrease in viscoelasticity and thixotropic behavior results in the clustering of opposite structural behaviors. With decreasing initial cooling temperature below WDT, although the structural behavior can be clustered with that at the initial cooling temperature near WDT, the gradual decreasing viscoelasticity behavior is presented. The direct microscopic evidence on the rheological deterioration and improvement are provided by two microscopic observation methods. Meanwhile, two different kinds of wax crystals with contrary influences on rheological behaviors are observed at initial cooling temperatures lower than the WDT. Furthermore, a hypothesis is proposed to explain the influence mechanism of initial cooling temperature lower than the WDT on the structural behaviors of waxy crude oil. In addition, different motion behaviors and mechanical performances of wax crystals are exhibited in response to the external load and impact, which further characterizes the intrinsic differences of inner structures of waxy crude oil formed at different initial cooling temperatures.

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Experimental Investigation of the Rheology and Crystal Morphology of Model Waxy Oils under Gelling Conditions

Cited by 12 publications

References 70 publications

New Method for Gelation Temperature Measurement without Disturbing the Crystal Network

New Method for Gelation Temperature Measurement without Disturbing the Crystal Network

Apparent wall slip effects on rheometric measurements of waxy gels

Effect of Initial Cooling Temperature on Structural Behaviors of Gelled Waxy Crude Oil and Microscopic Mechanism Investigation

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