Influence of Hydrocarbon Distribution in Crude Oil and Residues on Asphaltene Stability

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• 作者：Javier Dufour ; Jos A. Calles ; Javier Marugn ; Ral Gimnez-Aguirre ; Jos Luis Pea ; Daniel Merino-Garca
• 刊名：Energy & Fuels
• 出版年：2010
• 出版时间：April 15, 2010
• 年：2010
• 卷：24
• 期：4
• 页码：2281-2286
• 全文大小：878K
• 年卷期：v.24,no.4(April 15, 2010)
• ISSN：1520-5029

文摘

Flow assurance problems caused by asphaltene deposition are related to the solvent quality of the surrounding medium rather than the amount of asphaltenes. Traditionally, solvent quality has been focused on resins, which are the most similar fraction to asphaltenes, in terms of aromaticity and polarity. Still, no answer is available to the question whether resins (defined as the soluble fraction in n-heptane but insoluble in n-pentane) act as co-solvents or have a more critical interaction with asphaltenes. This work deals with the study of asphaltenes stability in two South American crude oils and their distilled residues (190⁺, 370⁺, and 565⁺). The total amount of asphaltenes for each sample has been determined by the IP-143 standard method. When asphaltene percentage is normalized to whole crude oil using the true boling point (TBP) data from distillation following the ASTM D-2812 standard, a shift to a greater asphaltene mass is observed when light cuts are removed. Stability of asphaltenes and aggregation kinetics have been assessed by focused-beam laser reflectance measurements (FBRMs). Differences between each crude oil and its residues are observed. FBRM evidence has been confirmed by transmittance analysis using a Turbiscan device. Resins (defined as C5-insoluble and C7-soluble) and an aromatic compound [α-methyl-naphthalene (αMN)] have been doped into the original crude, to assess their effect on stability. Results have shown that the C5−C7 fraction increases asphaltene stability to a similar extent as a diaromatic molecule, such as αMN. All of this evidence may indicate that the effect of C5−C7 resins and diaromatic addition and the removal of light ends have a similar impact on asphaltene stability, supporting the belief that the solvent quality as a whole rules asphaltene behavior.