Following a previously reported experimental procedure, a heavy petroleum sample was fractionated by mixing a predefined volume of oil with liquid propane above its saturation pressure at different propane/oil ratios. The separated fractions, considered two mutually saturated liquid phases in equilibrium at p and T separation conditions, were denominated solid residue and liquid extract and were characterized by chemical and spectroscopic methods including elemental compositional and SARA analyses, FTIR, and NMR. The results show that the amount yielded or produced increases for the solid residue and decreases for the liquid extract as the propane/oil ratio increases and that the four SARA components are present in both fractions, independently of the propane/oil ratio used in the fractionation process. The data also indicate that polar components are present in the liquid extract even at the highest dilutions that correspond to rather low solubility parameters. Complementary results show that after the flocculation process and the subsequent liberation of propane, the solid residue and the liquid extract were easily recombined with minimal losses by remixing both fractions. Physical and chemical analysis indicated that the recombined and the original oil presented similar characteristics in terms of API gravity, SARA, elemental composition, FTIR, and NMR, but substantial differences in their rheological behavior. The similarity between original and recombined oil is also evidenced by ¹H DOSY NMR that shows that sets of aggregates are present in the spectra for both oil samples.

中文翻译：

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丙烷诱导原油馏分分离的固体残渣和液体萃取物的表征

按照先前报告的实验程序，通过将预定体积的油与高于其饱和压力的液态丙烷在不同的丙烷/油比下混合，来分离重质石油样品。分离的馏分，被认为是在p和T处处于平衡状态的两个相互饱和的液相分离条件分别为固体残留物和液体提取物，并通过化学和光谱方法进行了表征，包括元素组成和SARA分析，FTIR和NMR。结果表明，随着丙烷/油比的增加，固体残留物的产量或产量增加，而液体提取物的产量降低，并且两种馏分中均存在四种SARA成分，而与分馏中使用的丙烷/油比无关过程。数据还表明，即使在对应于相当低溶解度参数的最高稀释度下，液体提取物中也存在极性成分。补充结果表明，在絮凝过程和随后的丙烷释放之后，通过将两种馏分重新混合，可以轻松地将固体残留物和液体提取物重新混合，损失最小。物理和化学分析表明，重组油和原始油在API重力，SARA，元素组成，FTIR和NMR方面表现出相似的特性，但它们的流变行为却有很大差异。原始油和重组油之间的相似性也可以通过以下方式得到证明：¹ H DOSY NMR表明这两种油样品的光谱中都存在聚集体。