东营凹陷沙三 、 沙四段石油运移地球化学特征及意义

摘 要　 利用生物标志化合物、 碳同位素和原油烷烃色谱等地球化学指标研究了东营凹陷沙 三段(Es 3 )、 沙四段(Es 4 )油气运移的基本规律。 油源对比证实, 利津和牛庄洼陷 Es 3 、 Es 4 生 油岩分别向其附近和周缘地区提供了油源。 根据 “ 地质色层” 原理, 分析了原油中烷烃含量、 nC 21 - / nC 22 + 比值、 甾烷 C 29 ααα ββ ββ+αα 比值、 烷烃主峰碳数、 δ 13 C 值、 原油密度和粘度等地 球化学指标的变化规律, 表明利津和牛庄洼陷内石油具有 “ 离心” 式运移的典型特征, 反映 了压实流盆地古流体势场对油气运移的控制作用。 研究结果对压实流盆地油气运移、 聚集理 论模型和模拟方法的研究具有重要的地质意义。     

Fractionation of azaarenes during oil migration

A comparative study of alkylbenzoquinolines in crude oils and rock extracts (bitumens) from Japan and Sumatra shows that the ratios of nitrogen-masked isomers (NMIs) to nitrogen-exposed isomers (NEIs), and the ratio of higher homologs to lower homologs is higher in crude oils than in corresponding bitumens. Also, a regular increase in the ratios of NMIs to NEIs with increasing migration distance is observed for a series of crude oils from the Sarukawa Oil Field, northeastern Japan. These results are attributed to the preferential migration of NMIs caused by their weak adsorption on clay minerals and/or their low solubility in interstitial water, and the selective removal of lower honologs caused by their irreversible adsorption onto clays during oil migration, which are regarded as geochromatographic phenomena. It is suggested that those ratios can be used to estimate the degree of fractionation of oils during primary and secondary migration.