鄂尔多斯盆地西南部长6段粘土矿物特征

根据物性、粘土矿物X 衍射和扫描电镜等测试分析,鄂尔多斯盆地西南部延长组长6 段超低渗透砂岩粘土矿物类型为绿泥石、伊蒙混层和伊利石,粘土矿物相对含量分带性明显,研究区的东部绿泥石含量较高,而西部伊蒙混层含量较高。粘土矿物特征与储集层物性的相关性分析认为,伊蒙混层含量、伊利石含量均与储集层孔渗性能呈负相关;绿泥石含量与储集层孔渗性呈正相关;研究区东部储集层的质量优于西部。

Characteristics of Clay Minerals in Chang-6 Member in Southwestern Ordos Basin

Based on the petrophysical property, clay mineral X-ray diffraction and SEM observation, the characteristic of clay mineral in super-low permeability sandstone of Chang-6 member of Yanchang formation in southwestern Ordos basin is studied. The result shows that the clay minerals consist of chlorite, illite/smectite mixed layer and illite; and the occurrence of chlorite is pore space lining or pore space filling, and the occurrence of illite/smectite mixed layer and illite is bridging or pore space filling; the relative content of clay minerals is characterized by obvious zonality, namely, high chlorite content appears in the eastern part of the studied area, and high illite/smectite mixed layer content occurs in the western part. According to the correlation analysis of clay minerals and the reservoir petrophysical property, the contents of illite/smectite mixed layer and illite show an inverse correlation to the porosity and permeability of the reservoir, while the content of chlorite manifests a positive correlation to the porosity and permeability, indicating that the quality of the reservoir in the eastern part is better than that in the western part of the studied area.