生油岩五环芳烃的热演化及成熟度参数

THERMAL EVOLUTION AND MATURITY PARAMETERS OF PENTACYCLIC AROMATIC HYDROCARBONS IN SOURCE ROCKS

塔里木盆地中生界生油岩中的五环芳烃化合物的热演化呈规律性变化。成熟度较低的样品中的含量较高，苯并芘和苯并荧蒽的含量较低。随着成熟度的增加，含量逐渐下降，而苯并芘和苯并荧蒽的含量不断增多，这表明两者的成因及其演化途径不同。前者可能为有机质早期演化的产物，而后者主要来自环化和芳构化作用。生油层剖面样品分析资料表明，苯并[e]芘／和（苯并[e]芘＋苯并[a]芘）／之比值是良好的成熟度参数，它们可指示生油岩成油高峰期。

The thermal evolution of pentacyclic aromatic compounds shows a regular change in Mesozoicsource rocks from the Tarim Basin, northwestern China. It is noted that low mature samples are highin perylene and low in benzopyrenes and benzofluoranthenes. With depth, the perylene concentrationdecreases gradually, whereas benzopyrenes and benzofluoranthenes increase, suggesting that the originand evolutionary pathway of these compounds be different. Perylene may be the product of organicprecursor during early diagenesis. However, benzopyrenes and benzofluoranthenes are mainly generated from cyclization and aromatization. Analytical data of systematic source rock samples indicate thatthe ratios of benzo[e] pyrene/perylene, (benzo[e] pyrene+benzo[a] pyrene)/perylene and benzofluoranthenes/perylene are potentially useful as maturity parameters, with their maximum values overlapping the oil-generation peak.