巴楚地区志留系柯坪塔格组储层致密影响因素

Impact factors of the tight reservoir of the Kepingtage formation of Silurian in Bachu area

根据沉积学和储层地质学的原理和研究方法,利用普通及铸体薄片、扫描电镜、压汞、物性等测试分析资料,在储层岩石学特征、物性及孔隙结构特征研究的基础上,从沉积环境、砂岩成分和结构及成岩作用3个方面,重点分析了柯坪塔格组储层致密的影响因素。结果表明,研究区柯坪塔格组主要分布在下临滨,水动力相对较弱,岩屑砂岩发育,塑性碎屑成分含量较高,压实作用强;颗粒粒度细—中粒,分选中等—好,磨圆次棱,形成的胶结物较多,胶结作用中等—强,以钙质胶结影响最大。压实作用和胶结作用是储层致密的主要因素,压实作用对储层原始孔隙的破坏程度大于胶结作用的破坏程度。溶蚀作用形成的次生孔不发育,且部分被沥青充填,抑制了后期的成岩作用,也导致储层不发育。

According to the principle and study method of sedimentology and reservoir geology and based on the analysis of the reservoir petrology feature, physical property and pore texture feature, the impact factors of the tight reservoir of the Kepingtage formation are analyzed by using the thin sections, scanning electron microscope, pres- surized mercury and physical property from the sedimentary environment, composition and structure of sandstone and diagenesis. The result shows that Kepingtage formation mainly is distributed in lower shoreface, whose hydron- amic intensity was relatively weak, the lithic sandstone developed, and the composition of the plastic fragment was higher, the diagenesis is strong, the cementation was medium to strong because of fine-medium grain, medi- um-good sorting and second prismatic rounding, the influence of calcium cementation is the largest for Kepingtage reservoir. The compaction and cementation are the main reasons for the tight reservoir, and the damage degree of the compaction was greater than that of the cementation for the original pore of the reservoir. Secondary pore resulted from the dissolution was not developed very well and some of the pores were filled in by asphalt, the diagenesis was restrained in the later stage, by which the reservoir was not developed.