Development of a new correlation to determine relative viscosity of heavy oils with varying asphaltene content and temperature

摘要

One of the important challenges in the oil industry is to transport high viscosity heavy oils through pipelines while minimizing potential transport issues due to implications of asphaltenes. After evaluation of what is available in the literature (Pal and Rhodes, 1989; Krieger and Dougherty, 1959), we have developed a new correlation for relative viscosity of heavy oils which is not only simpler with easy to obtain input data but also more accurate than the leading correlations published in the literature. For example, the proposed correlation requires the incorporation of only one fluid-specific parameter where the structure and size of unsolvated asphaltene nanoaggregate was taken based on the "Yen-Mullins" (Mullins et al., 2012) model. To check the accuracy and validity of the correlation along with the assumptions utilized, calculated values of the relative viscosity were cross-plotted against the available experimental data from the literature. The results were also compared with the results obtained from some of the leading published correlations, such as "Pal - Rhodes" (Pal and Rhodes, 1989) and "Krieger - Dougherty" (Krieger and Dougherty, 1959) correlations. The R-2 (R-squared) along with the other statistical parameters obtained for our model were shown to be superior to the other correlations considered, indicating that our correlation is able to explain the relative viscosity variations with respect to the selected parameters better than the subject set of correlations. In addition, we have also developed a methodology to predict the value of maximum packing volume fraction of asphaltene particles dispersed in deasphalted oils that can also be used in calculating the relative viscosity using "Krieger - Dougherty" (Krieger and Dougherty, 1959) and "Brouwers" (Brouwers, 2010) models.