A New Experimental and Modeling Investigation of Wax Precipitation in Pipelines Based on Asphaltene Content

In this paper, a new model is proposed for wax precipitation. Fugacity of the solid phase is calculated indirectly by considering the fugacity of the pure liquid phase. In this approach, crude oil is divided into five pseudo components using the SARA test results. Solubility parameters were calculated by SRK (Soave Modification of Redlich Kwong) equation of state, and the composition of components is calculated by employing Rachford Rice equation. Also, geneticalgorithm was used to improve the accuracy of results in WAT and wax weight. The average deviation of WAT (Wax Appearance Temperature) was 0.11 and 0.15% in the multi solid and solid solution models respectively, also the average deviation of the wax weight was 10.32 and 5.8% in the multi solid and solid solution models, respectively. The results showed that the solid solution model was more accurate in the prediction of wax precipitation in pipelines, as compared to the multi solid model. The optimized parameters in this solid solution model were more effective and had a dynamic influence. The multi solid and solid solution models had a remarkable accuracy with the experimental data. There was no logical explanation for asphaltene on wax precipitation and WAT. As a result, asphaltene was omitted in five crude oils in order to investigate the effect on the wax weight percentage and WAT. Results reveal that after omitting asphaltene, WAT and wax weight percentage were decreased.