鄂尔多斯盆地姬塬地区延长组成岩作用及孔隙演化定量分析

以岩心、岩石薄片观察为基础,结合电镜扫描、阴极发光、X射线衍射等分析方法,对研究区砂岩储层的成岩作用及其孔隙演化进行了研究。研究结果表明:其储层主要经历了压实作用、胶结作用和溶蚀作用,目前处于中成岩A期,Ro值在0.7%~1.1%之间,经历的古地温在90℃~130℃之间;对孔隙演化起主要控制作用的是压实作用,其次为胶结作用、溶蚀作用;压实作用使原始孔隙减少16.37%~20.02%,胶结作用可使孔隙减少4.79%~6.45%,溶蚀溶解作用对孔隙影响不大,孔隙仅增加0.91%~2.49%。

Diagenesis and porosity evolution quantitative analysis of Yanchang Formation in Jiyuan area,Ordos basin

The reservoir of Yanchang Formation in Jiyuan area in Ordos basin, is a set of subaquatic distributary channels and mouth bar sandstone bodies formed in delta front facies, and mainly composed of arkosic arenite, is a unique reservoir with low porosity（average of 13.37%） and exceptional low perme ability （average of 4.46 × 10^-3μm^2）. On the basis of core observation, thin section observation and SEM analysis, cathodoluminescence and x-ray diffraction, diagenesis and porosity evolution of reservoir sand are thoroughly studied in this area, which indicated that reservoir sand of Yanchang Formation underwent compaction, cementation and solution during the diagenesis, and now it is at the A-stage of middle diage nesis stage （Ro=0.7 %- 1.1% ,T= 90℃-130℃ ）. Compaction plays the most important role in porosity evolution. The compaction makes the primary porosity decrease 16.37%-20.02%, cementation reduces porosity by 4.79%-6.45%, solution increases porosity only by 0. 91%-2.49%.