Abstract
Composition and molecular mass distribution of n-alkanes in asphaltenes of crude oils of different ages and in wax deposits formed in the borehole equipment were studied. In asphaltenes, n-alkanes from C12 to C60 were detected. The high molecular weight paraffins in asphaltenes would form a crystalline phase with a melting point of 80–90 °C. The peculiarities of the redistribution of high molecular paraffin hydrocarbons between oil and the corresponding wax deposit were detected. In the oils, the high molecular weight paraffinic hydrocarbons C50–C60 were found, which were not practically detected in the corresponding wax deposits.
Highlights
Waxes and asphaltenes are the most important constituents of crude oils because they have a great influence on crude oil properties
It was found that the n-alkanes with a wide range of carbon numbers were present in oil asphaltenes, which were determined by gas chromatography (GC) (Fig. 1)
In asphaltenes 1–3, n-alkanes were present with a carbon number of 10–60; their molecular mass distribution (MMD) were polymodal with clearly marked predominance of one of the modes at C16–C18, C12–C14, and C54–C56, respectively
Summary
Waxes and asphaltenes are the most important constituents of crude oils because they have a great influence on crude oil properties. Waxes are a complex mixture of solid (at ambient temperature) hydrocarbons which consist mainly of paraffin hydrocarbons with a small amount of. Edited by Yan-Hua Sun naphthenic and aromatic hydrocarbons as well as polar compounds. Waxes that are composed primarily of normal alkanes (n-alkanes) with a chain length of C18–C30 and crystallize in large flat plates (macrocrystalline structures) with a melting point of 40–60 °C are referred to as paraffin waxes (Jowett 1984). Waxes, which consist primarily of the higher molecular weight n-alkanes within C30–C60, with a high share of iso-paraffins and naphthenes, and have much higher melting point ranges (above 60–90 °C), are referred to as microcrystalline waxes. According to Musser and Kilpatrick (1998), paraffinic and microcrystalline waxes have molecular weight ranges of 350–600 and 300–2500, respectively
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