四川盆地河包场须家河组碱性成岩作用

Alkali Diagenesis of Xujiahe Sandstone in Hebaochang Block in Sichuan Basin

四川盆地河包场须家河组首次发现了碱性成岩环境下典型的石英溶蚀现象和以石英溶蚀为典型特征的次生孔隙类型。通过镜下薄片鉴定、扫描电镜观察及X-衍射分析等方法,结合区域地质条件,对该地区碱性成岩作用特征及形成机理进行了深入研究。研究结果表明,须家河组砂岩经历了强烈的成岩作用,整体处于晚成岩B期,成岩环境经历了从早期酸性向晚期碱性的转变,碱性成岩作用改造使须二段砂岩物性明显改善。

The typical quartz dissolution of alkali diagenesis of Xujiahe formation in Hebaochang block in Sichuan basin is firstly discovered,which forms secondary porosity characterized by such a quartz dissolution.Based on the analyses of thin section,scanning electron microscope,X-ray diffraction,combined with the regional geology conditions,the characteristics and formation mechanism of alkali diagenesis in this area are studied.The results show that the sandstone of Xujiahe formation undergoes strong diagenesis and enters into the stage of late diagenetic B,with transition from early acidity to late alkalinity.The alkali diagenesis reconstructs the sandstone of Xujiahe formation and allows its physical property to be much better.