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钙屑砂岩在整个川西坳陷须家河组四段广泛发育,且普遍致密。采用铸体薄片、扫描电镜、物性分析和水岩实验等手段,对丰谷构造须四段钙屑砂岩的基本特征进行了分析,探讨了沉积环境、成岩作用和构造运动对该类型优质储层形成的控制作用。结果表明,研究区钙屑砂岩分选中等—好,成分成熟度低,主要的储集空间为粒间溶孔和残余粒间孔,属特低孔特低渗储层。沉积作用和成岩作用是钙屑砂岩优质储层形成的主控因素。其中,发育在高能相带、且碳酸盐岩岩屑含量高(>90%)是钙屑砂岩优质储层发育的先决条件;而埋藏成岩过程中有机酸的溶蚀、烃类的早期充注和早期方解石胶结物的少量生成是钙屑砂岩优质储层孔隙保存及次生溶孔形成的关键。
Calcareous sandstone is widely developed and generally dense in the fourth member of Xujiahe Formation in the whole western Sichuan depression. The basic characteristics of calcareous sandstone in the fourth member of Fenggu structure are analyzed by means of casting thin slice, scanning electron microscope, physical property analysis and water-rock experiment. The effects of sedimentary environment, diagenesis and tectonic movement on the type of high-quality reservoir The formation of the control role. The results show that the calcareous sandstones in the study area are middle-good and low in maturity. The main reservoir space is intergranular dissolved pores and residual intergranular pores, belonging to the ultra-low-porosity and ultra-low permeability reservoirs. Deposition and diagenesis are the main controlling factors for the formation of high-quality reservoirs of calcium sandstone. Among them, the development of high-energy facies belts, and carbonate rock cuttings content is high (> 90%) is a prerequisite for the development of high-quality calcium carbonate sandstone reservoirs; organic acid erosion during burial diagenesis, hydrocarbon early charge And early calcite cementation is a small amount of calcium carbonate sandstone reservoirs of high quality reservoirs and secondary porosity formation key.