油气地质与采收率2017，Vol.24Issue(5)：34-39,6.
鄂尔多斯盆地苏东地区下古生界马五5亚段白云岩成因及特征
Genesis and characteristics of Lower Palaozoic dolomite of submember Ma55 in Majiagou Formation,Sudong region in Ordos Basin
摘要
Abstract
In order to study the characteristics and genesis of dolomite in the main gas reservoirs of the Lower Paleozonic submember Ma55 in the Sudong region,methods such as thin section observation,X-ray diffraction,scanning electron microscopy,cathodoluminescence and trace elements analysis were used to analyze the dolomite samples.The results show that the Lower Paleozoic submember Ma55 in the Sudong region are characterized by dolomitization,which can be concluded as follows:There are three types of dolomite:penecontemporary dolomite,reflux seepage dolomite and buried dolomite in submember Ma55 of the Majiagou Formation.The original intergranular pores developed well in the dolomite reservoirs,and they are dominated by intercrystal pores and suintercrystal dissolved pores.Occasionally,some non-constitutive dissolution pores,residual intergranular pores and a small amount of paste pores were observed.Cathodoluminescence experimental results show the presence of light-emitting micrite dolomite (containing sand-gravel clastics)indicating the development of muddy gravel dolomite in the study area.The X-ray diffraction results show that the order degree of penecontemporary dolomite is not high,average 0.443,and reflux seepage dolomite has a high degree of order,average 0.574.The ordered degree of buried dolomite is as high as 1.The dolomite composition is simple,and the ratio of Ca2+and Mg2+ is close to the stoichiometric CaMg (CO3)2,which verifies the accuracy of the order degree of dolomite obtained by X-ray diffraction.And the main trace element characteristics indicate that the reflow infiltration dolomite mainly occurs in seawater diagenetic medium.关键词
准同生型白云岩/回流渗透型白云岩/白云石化/有序度/下古生界/苏东地区/鄂尔多斯盆地Key words
penecontemporary dolomite/reflux seepage dolomite/dolomitization/order degree/Lower Paleozoic/Sudong region/Ordos Basin分类
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宋磊,宁正福,丁冠阳..鄂尔多斯盆地苏东地区下古生界马五5亚段白云岩成因及特征[J].油气地质与采收率,2017,24(5):34-39,6.基金项目
国家自然科学基金项目“页岩储层纳孔微缝耦合系统全息表征方法研究”(41672132). （41672132）
