济阳坳陷古近系—新近系泥岩孔隙结构特征

对济阳坳陷东营凹陷和沾化凹陷古近系—新近系泥岩的岩心样品,进行了X衍射全岩物相测试,有机碳测定,孔隙度、渗透率测定及扫描电镜和显微镜下观察,发现泥岩中普遍含碎屑矿物,其中长石含量较高,粘土矿物以碎屑粘土为主,泥岩中碳酸盐矿物含量较高.泥岩中各种面状孔隙是主体孔隙,由微孔隙构成,孔隙含量较高,分布较均匀.泥岩孔隙结构基本可归纳为细孔喉型、粗孔喉型及混合过渡型等三种类型.最后分析探讨了影响泥岩孔隙结构主要因素为:①碳酸盐含量使孔隙基本面貌产生差异;②压实作用使孔隙度减小,欠压实对孔隙结构有保护作用;③有机质丰度、成熟度及赋存状态与溶蚀孔隙发育关系密切相关;④有机质富集有利于异常压力发育,对孔隙起保护作用.

Characteristics of Pore Structures of Paleogene-Neogene Argillaceous Rocks in the Jiyang Depression

Samples of the Paleogene-Neogene argillaceous rocks in the Dongying and Zhanhua sags of the Jiyang depression have been analyzed on the basis of the X-ray diffraction test of the bulk rock. The studies of organic carbon, porosity and permeability show that detrital minerals are widespread in the, in which the feldspar content is higher. The clay minerals are dominated by detrital clay, and the carbonate content is relatively high in the argillaceous rocks. Flat pores are the main pores formed by micropores and distributed rather evenly in the argillaceous rocks, in which the pore content is higher than that in sandstone. On the whole, the pore structures can be grouped into three basic types, i. e. fine pore throat, thick pore throat and mixed pore throat. The main influencing factors on the pore structures in the argillaceous rocks are considered as follows: (1) the different carbonate contents cause differences in the basic features of the pores; (2) compaction causes the porosity to reduce, and undercompaction protect the pore structure; (3) the abundance and maturity as well as occurrences of the organic matter have close relations with the corrosion pores; and (4) the abundant organic matter is favorable for abnormal pressure to grow, which can protect the pore system.