Ruthenium-ion-catalyzed oxidation (RICO) has been used to investigate asphaltenes from three oils with the same origin in the Juquan Basin and three oils with the same origin but with different degree of biodegradation in the Turpan Basin, Northwest China. The preliminary resultsshowed that the biomarkers bonded on the asphaltenes with the same origin is similar and is correlated with the freebiomarker in saturates. The bonded biomarkers have norelationship with the biodegradation. An application on the severely biodegraded oils is reported here. The biomarkerand benzenecarboxylic methyl esters reflecting the structure of the asphaltenes after RICO should provide a new way for oil-source correlation and it should be specially useful forseverely biodegraded oil-source correlation. Ruthenium-ion-catalyzed oxidation (RICO) has been used to investigate asphaltenes from three oils with the same origin in the Juquan Basin and three oils with the same origin but with different degree of biodegradation in the Turpan Basin, Northwest China. The preliminary resultsshowed that the biomarkers bonded on the asphaltenes with the same origin are similar and is correlated with the free biomarker in saturates. The application bio-keying with the free biomarker in saturates. The application on severely biodegraded oils is reported here. The biomarkerand benzenecarboxylic acid methyl esters reflecting the structure of the asphaltenes after RICO should provide a new way for oil-source correlation and it should be specially useful forseverely biodegraded oil-source correlation.