• 责任者：Sun Xiuli (School of Earth Environments and Water Resources ; Yangtze University ; Wuhan 430100 ; China) ; Wan Yonggang
• 刊名：Acta Petrolei Sinica
• 出版年：2013
• 卷期：34(6)
• 关键词：轻烃 ; light hydrocarbon ; 实验研究 ; experimental studies ; 塔里木盆地 ; Tarim Basin
• 页码：p.1060-1069
• 图表：6 illus., 1 table, 27 refs.
• 分类号：1003
• issnNo：ISSN0253-2697
• isbnNo：CN11-2128/TE

     Light hydrocarbon indices of C5-C8 play an important role in petroleum exploration and exploitation, while a large number of uncertainties occur in their applications due to the volatile nature of crude oils. A simulation experiment on natural evaporation of a condensate sampled from Ordovician marine formations in the central area of the Tarim Basin was conducted in the laboratory. On the basis of experimental results, a series of light hydrocarbon indices were screened and refined in order to make them more resistant to natural evaporation and more functional in applications. The results indicated that impacts of natural evaporation on C5-C8 light hydrocarbon indices largely depend on both molecular weights and chemical structures of individual compounds. Evaporation amounts of C5-C8 normal alkanes decrease progressively with increase of carbon number, and those of C7 compounds with different molecular configurations follow an descending order of isoheptane, n-heptane, methylcyclohexane and toluene, while dimethylcyclopentanes show an eguivalent amount of natural evaporation. In general, natural evaporation has a minor impact on the ratios of normal alkanes to cycloalkanes and isoalkanes to cycloalkanes, and so does on ratios of light hydrocarbons that have similar natural evaporation rates and identical molecular configurations. During oil evaporation, stable carbon isotopic compositions of individual C6-C8 compounds within liquid residues are progressively enriched in 13 C with increasing evaporation, while the varying extent of carbon isotope ratios for C6-C8 normal alkanes decreases gradually with increase of carbon number. When an evaporative loss is less than 70 %,  δ^13C values of C6-C8 normal alkanes show no much variations （〈1.0‰） ; and when an evaporative loss exceeds over 70%, δ^13C values of all nor mal alkanes, isoalkanes and light aromatics vary obviously （ 〉1.0‰）, with the exception of cycloalkanes whose δ^13C value still chan-ges a little （~ 1.0‰）, this indicated that δ^13C value of cycloalkanes can be used with confidence. Thus, some light hydrocarbon indices less affected by natural evaporation, such as ratios of normal alkanes to eycloalkanes and isoalkanes to eyeloalkanes, and δ^13C value of cycloalkanes, were applied successfully to maturity determination and type classification of crude oils in the central area of the Tarim Ba- sin, demonstrating a good practicability and bright application future.