鄂尔多斯盆地东南部长6成岩作用及其对孔隙的影响

Diagenesis and its influence on porosity of Chang 6 reservoir in southeast Ordos Basin

应用薄片鉴定、扫描电镜、X-衍射等方法分析鄂尔多斯盆地东南部长6储层岩性特征、成岩作用及其对储层孔隙的影响。结果表明,研究区长6储层以长石砂岩和岩屑质长石砂岩为主,砂岩颗粒多为磨圆度中等-好,分选性中等,其成岩阶段主要处于中成岩A期。主要成岩作用有压实作用、胶结作用、溶蚀作用、交代作用、其中压实作用和胶结对储层孔隙空间起破坏作用,使储层孔隙分别减少了原始孔隙的68.8%和16.90%;而后期的溶蚀作用对储层孔隙空间起建设作用,使储层孔隙增加了原始孔隙3.67%,为油气聚集空间贡献了一定的作用。

Based on such means as thin section identification, scanning electron microscope and X-ray diffraction, the authors stud-ied reservoir lithology, types of diagenesis and influence on pore evolution of Chang 6 reservoir in southeast Ordos Basin. The mainsandstone types of Chang 6 reservoir are arkose and lithic feldspathic sandstones. Most sand grains are round-subangular and moder-ately sorted. The sandstone belongs to stage A of middle diagenetic stage. Diagenesis includes compaction, cementation, dissolutionand metasomatism. Compaction and cementation reduced inidal pore volume by 68.8% and 16.90% respectively. Later, dissolution in-creased pore volume by 3.67%, which was useful to oil and gas accumulation.