We conducted a comprehensive experimental study on the effect of the CO₂ injection rate (flow rate: represented by the macroscopic capillary number, N_c) on CO₂ saturation ($S_{{\mathrm{C}\mathrm{O}}_2}$) and the CO₂ distribution in porous, brine-saturated Berea sandstone. We measured two independent geophysical parameters, P-wave velocity (V_p) and electrical resistivity (ρ*), to monitor the two-phase flow. V_p showed clear dependency on $S_{{\mathrm{C}\mathrm{O}}_2}$ in the transition zone between the capillary limit (CL) and the viscous limit (VL), but not near the CL. The ${V_{\mathrm{p}}-S}_{{\mathrm{C}\mathrm{O}}_2}$ relationship showed that the characteristic size of connected CO₂ volumes decreased with increasing N_c, whereas resistivity increased continuously with increasing $S_{{\mathrm{C}\mathrm{O}}_2}$. Therefore, resistivity is sensitive to $S_{{\mathrm{C}\mathrm{O}}_2}$ under flow conditions between the CL and VL. The ρ*–$S_{{\mathrm{C}\mathrm{O}}_2}$ relationship showed that CO₂ penetration increased with increasing N_c. These results indicate that we can use V_p and ρ* to monitor CO₂ flow in pore spaces because the injected CO₂ forms pathways and replaces brine under a wide range of N_c values.

我们对CO ₂注入速率（流速：由宏观毛细管数N _c表示）对CO ₂饱和度（${\mathrm{小号}}_{{\mathrm{C}\mathrm{Ø}}_2}$）和在盐水饱和的Berea多孔砂岩中的CO ₂分布。我们测量了两个独立的地球物理参数，即P波速度（V _p）和电阻率（ρ *），以监测两相流。V _p明显依赖于${\mathrm{小号}}_{{\mathrm{C}\mathrm{Ø}}_2}$在毛细管极限（CL）和粘性极限（VL）之间的过渡区域，但不在CL附近。的${V_{\mathrm{p}}-\mathrm{小号}}_{{\mathrm{C}\mathrm{Ø}}_2}$关系表明，连接的CO ₂体积的特征尺寸随N _c的增加而减小，而电阻率则随n _c的增加而连续增加${\mathrm{小号}}_{{\mathrm{C}\mathrm{Ø}}_2}$。因此，电阻率对${\mathrm{小号}}_{{\mathrm{C}\mathrm{Ø}}_2}$在CL和VL之间的流动条件下。该ρ * -${\mathrm{小号}}_{{\mathrm{C}\mathrm{Ø}}_2}$的关系表明，随着N _c的增加，CO _2的渗透增加。这些结果表明，我们可以使用V _p和ρ *来监视CO ₂在孔空间中的流动，因为注入的CO _2会形成路径并在很大的N _c值范围内替代盐水。