This study experimentally investigated the impact of CO₂ miscible flooding on oil recovery and alteration of rock properties in two carbonate cores consisting of more than 98% calcite: Edwards white representing a homogenous medium mainly consisted of micropores, and Indiana limestone representing a heterogeneous medium mostly composed of macropores. Several methods were applied to investigate the alteration of rock properties by CO₂-water-carbonate minerals interactions: 1) Core flooding to measure overall changes, 2) MICP and X-ray CT to analyze small pores and large pores, respectively, 3) SEM, PCM, and ICP to verify physical and chemical reactions.

Oil recovery was higher in Edwards white than in Indiana limestone, since characteristic of Edwards white contributes to sufficient contact time and stable displacement between oil and CO₂. From the analysis of the alteration of rock properties in homogenous sample, dissolution facilitates the enlargement of pore sizes. Therefore, fluid flow becomes more favorable. The precipitation is not critical determinant of alteration process, despite the high proportion of small pores. For heterogeneous sample, both dissolution and precipitation significantly affect to alteration of pore structure. Particularly, the precipitation seriously damaged to the main flow channels. These undesirable effects on fluid flow appeared at injection point, which was exposed to fresh CO₂ for a long time.

This study suggests that pore structure analysis allows a more exact interpretation and judgment of the alteration of pore structure by dissolution and precipitation and can assist in designing injection plans, particularly near the injection area or in complex pore structure.

这项研究通过实验研究了CO ₂混相驱油对两个碳酸盐岩心（含98％以上方解石）的采收率和岩石性质变化的影响：Edwards White代表均质介质，主要由微孔组成； Indiana石灰岩代表非均质介质。由大孔组成。几种方法被用来研究CO _2-水-碳酸盐矿物相互作用引起的岩石性质的变化：1）岩心驱替以测量总体变化，2）MICP和X射线CT分别分析小孔和大孔，3） SEM，PCM和ICP验证物理和化学反应。

爱德华兹白油的采收率高于印第安纳州石灰石，因为爱德华兹白油的特性有助于充分的接触时间和油与CO ₂之间的稳定置换。从均质样品中岩石性质的变化分析，溶解促进了孔径的扩大。因此，流体流动变得更有利。尽管小孔比例很高，但降水并不是改变过程的关键决定因素。对于异质样品，溶解和沉淀都会显着影响孔结构的变化。特别是，降水严重损害了主流道。这些对流体流动的不良影响出现在注入点，该注入点长时间暴露于新鲜的CO ₂中。

这项研究表明，孔隙结构分析可以更准确地解释和判断由于溶解和沉淀引起的孔隙结构变化，并且可以帮助设计注入计划，尤其是在注入区域附近或复杂的孔隙结构中。