【摘要】 对鄂尔多斯盆地西峰油田三叠系延长组六个油砂样品中游离烃、封闭烃、束缚烃的饱和烃馏分进行了GC—MS分析。样品中长链烷基苯在C16-C20范围内具有较明显的偶碳优势。研究表明:长链烷基苯的演化受成熟度的影响,表现为随着成熟度的增加,长链正构烷基苯的碳数分布前移,长链烷基苯异构体相对丰度减小;而正构烷基苯相对丰度有增加的趋势。长链烷基苯主要是细菌、藻类和高等植物类脂化合物中脂肪酸在粘土矿物催化下发生环化脱羧再芳构化或单环芳烃与脂肪酸烷基化反应形成的产物。已形成的长直链烷基苯通过β分裂、单分子均裂形成苯甲基、烯烃,苯甲基通过氢转移到长链烷基苯的α碳上,烯烃再与α碳结合形成带支链的烷基苯。长链烷基苯的检出进一步验证了当时沉积物处于较强还原环境。长链烷基苯在不同赋存状态烃的分布特征,可以应用于油气聚集时间和成藏差异的研究。更多还原

【Abstract】 Saturated hydrocarbon fractions of free oil, sealing oil and bound oil,which are extracted from six oil sands of Yanchang Formation in Xifeng oilfield of northwestern Ordos Basin, Northwest China, have been analyzed by GC/MSD(6890N/5973N)in order. The long chain alkyl benzenes in six samples show an even carbon number predominance ranging from C_ 16 to C_ 20 in carbon number. Our study shows that maturity has an effect on the evolution of long chain alkyl benzenes, that is, with the increase of maturity, the carbon number distribution of alkyl benzenes shifts to the lower homologues isomers; relative abundance of alkyl benzenes isomeride decreases, whereas n-alky benzenes increase. Long chain alkyl benzenes is the product of cyclization-decarboxylation-aromatization of fatty acid, with the help of clay minerals catalytic effect, which comes from bacteria, seaseed and higher plant lipid; or the reaction product of monocylic aromatics and fatty acid alkyl group under the same conditions. The formed long and linear chain alkyl benzene changes into benzene methyl and alkene through β-scission and monomolecular homolysis, and then benzene methyl shifts to the position of α-Carbon in the long chain alkyl benzene through H-transfers. The finding of long chain alkyl benzene proves the relatively strong reducing environments during deposition at that time. The distribution characteristics of long chain alkyl benzene in different state hydrocarbon can be used for petroleum accumulation dating.更多还原