Ruthenium-ion-catalyzed oxidation of asphaltenes of heavy oils in Lunnan and Tahe oilfields in Tarim Basin, NW China

The application of ruthenium-ion-catalyzed oxidation (RICO) products of asphaltenes of heavy oils in Lunnan and Tahe oilfields and Well TD2 in oil–oil and oil–source correlations was explored. The RICO products included n-alkanoic acids, α,ω-di-n-alkanoic acids, branched alkanoic acids, tricyclic terpanoic acids, hopanoic acids, gammacerane carboxylic acid, regular sterane carboxylic acids and 4-methylsterane carboxylic acids. The n-alkyl chains and biomarkers bonded on the asphaltenes were uneasily to be biodegraded. The distribution and absolute concentration of n-alkanoic acids in RICO products of heavy oils in Lunnan and Tahe oilfields are different from those of Well TD2. The biomarkers bonded on the asphaltenes, especially steranes, have a similar distribution to that of the counterparts in the saturated fraction. The sterane carboxylic acids and 4-methylsterane carboxylic acids in the RICO products of heavy oils in Lunnan and Tahe oilfields, dominated by C30 sterane and C31 4-methylsterane carboxylic acids, respectively, are significantly different from those of Well TD2, whose dominating sterane and 4-methylsterane carboxylic acids are C28 sterane and C29 4-methylsterane acids, respectively. The RICO products of asphaltenes further indicate that the Upper Ordovician may be the main source rock for the twice charged hydrocarbon of heavy oils in Lunnan and Tahe oilfields.