Correlation Between Oil Composition and Paraffin Inhibitors Activity

Abstract Highly paraffinic crudes were characterized by means of physico-chemical analysis (pour point, cloud point and API gravity) and hydrocarbon analysis (wax content, paraffin class-type separation, gel permeation chromatography and high temperature simulated distillation). Although all the studied samples were typical light crudes (32 - 43 API), their high paraffin content was responsible for solidification even above room temperature (33 - 48 C). Several commercial paraffin inhibitors were evaluated with these crudes, being pour point depression the selected activity criteria. Some products evidenced good activity when added to three of the crudes under study, while others induced insignificant changes in the pour point under similar dosages. Correlations between crude oil composition and paraffin inhibitors activity were assessed. The normal / cyclo+iso-paraffins ratio of the crudes that were not affected by the paraffin inhibitors was found higher. The molecular weight distribution (GPC) of the crudes sensitive to additives showed a bimodal character. Additionally, the Concentration of components with more than 24 carbon atoms was found lower than 39 % wt, as determined by simulated distillation. On the other hand, the crudes insensitive to the action of inhibitors displayed monomodal molecular weight distributions with larger contributions of heavy components (more than 52 % wt). Doping experiments carried out with Cl 3-C20 and C20-C44 paraffin extracts and using polarized light microscopy for cloud point determinations, supported the previous findings and permitted to assess the inefficiency of commercial paraffin inhibitors for crudes rich in C24+ alkanes. P. 681