Some advances in crude oil rheology and its application

Abstract

Waxy crude oil exhibits complex shear-and-thermal-history-dependent non-Newtonian behaviors. In the past 10 years, driven by the petroleum industry, crude oil rheology has been an active field. Studies on crude oil rheology have been passing a way from simply relying on rheological measurements, through quantitative experimental simulation of shear and thermal history effects in pipelining, to recent development of correlation between flow properties and shear and thermal history. Currently, the study is toward quantitative inquiry of relations between the rheological behaviors and micro-structures of wax crystals as well as oil compositions. Advances achieved by the author' team are summarized, including simulation of the thermal and shear history effects, correlations and computation of flow properties, fractal characterization of morphology and structure of wax crystals, relations of rheological behaviors to fractal dimension and oil compositions, and the most successful example of the application of rheology in crude oil pipelining. Future studies are prospected.

Shear-Induced Change in Morphology of Wax Crystals and Flow Properties of Waxy Crudes Modified with the Pour-Point Depressant

“…S g became higher and higher with increased time of shear, while the grain size and surface of wax crystals became smaller and smaller, resulting in the decrease in the fractal dimension of wax crystals. The experimental result is in accordance with the studies by Lorge et al, Kané et al, , Venkatesan et al, Zhang et al, and Li et al…”

“…Nevertheless, no effort has been made thus far in establishing a quantitative relation between the shear history effect and change in morphology of waxy crystals according to the literature. Although studies by El-Gamal et al, Lorge et al, Kané et al, , Venkatesan et al, Zhang et al, and Li et al have shown that shear could change the morphology and structure of wax crystal congeries, few of them dealt with direct quantitative analysis on the morphology and structure of wax crystal congeries. Because of the high irregularity of the wax crystal microstructure, its quantitative characterization was a difficult job.…”

The effects of SKO on Assam crude oil

“…the addition of SKO to CO samples as in Fig. 4 , which is considered to be closely related to sample composition, such as wax, resins, and asphaltenes contents [ 13 , 55 – 57 ].…”

Application of Rheo-optic In Situ Measurement Technology to Study Waxy Crude Oil Rheology

“…1 Research on crude oil rheological properties is important for the determination of safety parameters and operational adjustments during storage and transportation. 2 − 4 In general, properties of crude oil, such as high wax appearance temperature (WAT), high pour point, and high wax content, can contribute to accidents that reduce oil transportation efficiency and block pipelines. Therefore, heat treatment or the addition of pour point depressants (PPDs) is generally used to improve the rheological properties of crude oil, but high production costs are a disadvantage.…”