Gelation and Breakage Behavior of Model Wax–Oil Systems: Rheological Properties and Model Development

Abstract

Gelation and breakage of model wax−oil systems is investigated using microscopy, densitometry, rheometry, and XRD. Various model waxy oils are prepared, including 1 to 20 wt % (w/w) macrocrystalline wax in dodecane, 1 to 20 wt % microcrystalline wax in dodecane, and 5 wt % macrocrystalline wax in Primol 352. The influence of shear history, thermal history, and fluid composition is ascertained. A novel gel breakage model is introduced which spans the entire mechanical response of wax gels from initial Hookean behavior at low strains to equilibrium slurry flow at the infinite strain limit. The local rheology model will benefit shut-in and restart processes of waxy crude pipelines via application of standard fluid mechanics relationships.

Numerical study of pipeline restart of weakly compressible irreversibly thixotropic waxy crude oils

“…To examine various values of the compressibility number, d ¼ 4310 23 and d ¼ 4310 25 are considered while the other parameters are fixed. The pressure profiles corresponding to these parameters are shown in Figure 12a and b.…”

“…The gel state is assumed to follow a point function of absolute strain instead of time. [21][22][23] Hence, a strain-dependent apparent viscosity is established without a true yield stress. Gelled waxy crude oil may be classified as an irreversible thixotropic material with a known degradation and breakdown behavior.…”

“…Gel degradation kinetics has previously been established as a first-order (exponential decaying 7,24,25 ) and third-order process with respect to absolute imposed strain or time. 21,23 Here, firstorder and third-order degradation kinetics means that the rate of gel structure breakage is a first-order or third-order function of the structural parameter, respectively.…”

Numerical study of flow restart in the pipeline filled with weakly compressible waxy crude oil in non-isothermal condition

“…Creeping flow is defined by a corresponding high viscosity [6,[21][22][23][24]. In alternate approach, initial creep can be associated with elastic deformation [25]. However, in this study, initial creeping flow is accounted for by a high viscosity of the gel.…”

Estudo Sobre a Influência Da Contração Do Petróleo Ao Gelificar No Reinício Do Escoamento

“…A viscosidade dos fluidos Newtonianos varia inversamente com a temperatura absoluta, apresentando um comportamento exponencial conforme a lei de Arrhenius (28).…”