METHOD OF SEPARATING OIL IN ORDER OF POLARITY AND ITS CONTRIBUTION TO COMPREHEND THE CHARACTERISTICS OF STABLE CARBON ISOTOPE OF CRUDE OIL

A method of separating oil by polarity has been constructed for exploring the relationship between the polarity of organic molecules and the δ13C of them in crude oil.We divide a sample of oil from Shengli oil field into five parts by this method,and measure the δ13C of each part.Similarly,we divide another sample of the same oil into four parts by the old method,and measure theδ13C of each part.By contrasting these two methods in their steps of experiments and separating results,we conclude that:(1) they are similar that the polarity increases from the first component to the last component in both methods;yet(2) they are distinct in details: in the polar method oil sample is separated into five parts,one more than that in the old method and more meticulous;(3) by comparing each part of them,we point that aromatic hydrocarbon and nonhydrocarbon both have a large span in polarity;and(4) we show that the polarity of organic molecules in oil increases as their δ13C value rises in isotopic theory and the analysis of our experiment results.In the end,we construct a mathematical model on this conclusion to explain the reverse order in oil.