鄂尔多斯盆地R地区长6储层成岩演化与孔隙特征研究

Diagenetic evolution and pore characteristics of Chang 6 reservoir in R area of Ordos Basin

借助阴极发光、SEM、X衍射、铸体薄片、压汞等测试分析技术,探讨了鄂尔多斯盆地R地区长6储层砂岩成岩演化序列、成岩相、微观孔隙特征,结果表明:发育于三角洲平原的长6储层,岩性以细粒长石砂岩为主,先后经历了压实、胶结、溶蚀等成岩作用,处于中成岩晚期阶段,其中胶结作用对储层物性破坏显著,是储层致密的主要原因;结合沉积环境及孔隙特征将成岩作用划分为5种成岩相,长6储层原生残余粒间孔与次生溶蚀孔混合发育,平均孔隙度6.71%,平均渗透率0.46×10^(-3)μm^2,储层均质性较强,属特低孔特低渗储层;在孔隙演化过程中,机械压实、胶结作用对储层物性起破坏作用,溶蚀作用则对储层物性起改善作用。

By using cathode-luminescence,SEM,x-ray diffraction,casting thin section and intrusive mercury,the diagenetic evolution sequence,stage and micro-pore characteristics of Chang 6 reservoir in R area of Ordos Basin was discussed.The results show the main lithology is feldspathic sandstone and it mainly experienced compaction,cementation and dissolution.The cementation made an obvious damage on reservoir property,which was the main reason for reservoir density.Combined with sedimentary environment and pore characteristics,digenesis was divided into 5 diagenetic facies.Primary and secondary pore were mixedly developed,the average porosity is 6.71% and average permeability is 0.46 ×10^(-3)μm^2.This reservoir has strong heterogeneity and it belongs to low porosity and low permeability.In process of pore evolution,mechanical compaction and cementation play a destructive role in reservoir physical properties,while the solution can improve the physical properties.