鄂尔多斯盆地靖边潜台西侧奥陶系马五4亚段岩溶作用与孔隙演化

The Karstification and Porosity Evolution of Ma54 Sub Member, Ordovician Majiagou Formation, Western Jingbian Tableland in the Ordos Basin

摘要: 岩溶作用对鄂尔多斯盆地靖边潜台西侧奥陶系马家沟组马五4亚段储层的形成及分布具有重要意义。在大量钻井岩心及铸体薄片观察、扫描电镜鉴定等分析方法的基础上，对研究区马五4亚段岩溶作用与孔隙演化规律进行了深入研究。研究结果表明：研究区马五4亚段碳酸盐岩储层经历了同生期岩溶、表生期岩溶和埋藏期岩溶3期岩溶作用；且不同岩溶作用对该储层的孔隙形成和演化起关键性作用，根据研究区马五4亚段孔隙形成和演化特征，将其划分为准同生阶段——孔隙建设期、近地表浅埋藏阶段——孔隙胶结破坏期、风化壳大气淡水阶段——孔隙溶解建设期、中–深埋藏成岩阶段——孔隙充填破坏期4个演化阶段，并建立了孔隙演化模式。

Abstract: The karstification was of great significance for the formation and distribution of the reservoir in the Ma54 of Ordovician Majiagou Formation in the western Jingbian tableland in the Ordos basin. Based on the analysis of observation of drilling cores, casting slices and scanning electron microscope, the karstification and regulation of porosity evolution in Ma54 were studied in depth. The results show that the areas of carbonate karst of Ma54 sub member are divided into three categories, such as syngenetic, supergene and buried stage karstifications, and different karstifications play an important role on the formation and evolution of the reservoir porosity. According to the characteristics of porosity formation and porosity evolution, the Ma54 is divided into four stages, such as penecontemporaneous stage—pores construction period, shallow burial stage—pores cementation destruction period, uplift weathering stage—pores corrosion construction period and mid-deep-burial stage—pores-filling and destruction period; porosity evolution models are established.