为研究有机质在粘土矿物中的赋存状态和二者的结合方式以及有机质的热稳定性,提取济阳坳陷东营凹陷古近系沙河街组泥质烃源岩和东海陆架表层泥质沉积物中的粘土组分(粒径〈2μm),依次进行索氏抽提、碱性水解和酸性水解处理,得到原始和相继处理过程所得碱解和酸解粘土样品及相应的有机组分,继而进行原始和碱解、酸解粘土样品的微观形貌(SEM)、比表面积(BET)、X-射线衍射(XRD)和热重/微分热重(TG/DTG)分析对比。结果显示,索氏抽提有机质主要赋存于粘土矿物外表面和堆积于孔隙中,碱解有机质主要赋存于粘土矿物边缘破键处,而酸解有机质主要赋存于膨胀型粘土蒙皂石层间。前者为物理吸附或束缚的游离有机质,后两者为化学吸附的结合有机质。有机质与粘土矿物的不同结合关系造成它们热稳定性的差异,显示出二者间复杂的作用关系及其对生烃的多阶段性影响。研究不同赋存态有机质的相对和绝对数量对深入研究油气成因和烃类初次运移具有十分重要的意义。
To study the occurrence of absorbed organic matter in clay minerals, the bounding of organic matter and clay minerals, and thermostability of the organic matter, we took samples from the argillaceous hydrocarbon source rocks of the Neocene Shahejie Formation in Jiyang Depression and from mud on surface of the East China Sea continental shelf. Clay components ( 〈 2 μm) were obtained from theses samples for sequential treatments including soxhlet extract,base hydrolysis and acid hydrolysis. The original clay samples and their absorbed or- ganic matters as well as that obtained during base hydrolysis and acid hydrolysis were compared in respects of microscopic shape ( SEM), specific surface area ( BET), X-ray diffraction (XRD) and thermal gravity/differen- tial thermal gravity (TG/DTG). Results show that extracted organic matter mainly occurs on the outer surface and in micro-pores of clay minerals, base hydrolysed organic matter can be found near broken bound on margin of clay minerals, and acid hydrolayse organic matter mainly occurs in inter-layers of expandable smectite in clay minerals. The former is free organic matters with physical adsorption or bound and the latter two are the com- bined organic matter with chemisorption. The various associative relations between the organic matter and clay minerals caused difference in their thermostability and further affected the hydrocarbon generation in the area. A study on the absolute and relative contents of organic matters with various occurrences is therefore considered significant for understanding the hydrocarbon origin and its primary migration.