When CO₂ is injected into aquifers, CO₂ will dissolve into the water phase. CO₂ dissolution initiated by diffusion, will increase the density of the water phase and thereby commence the convective flow of CO₂. The objective of the presented work was to visually investigate the effects of permeability on the convective mixing of supercritical CO₂ with water at realistic reservoir conditions (pressure and temperature). This required construction of a high-pressure transparent Hele-Shaw cell that allowed visualization of CO₂ transport, and the development of experimental procedures.

To develop the high-pressure Hele-Shaw cell, stress/strain calculations and simulations were carried out to select the best building materials for realistic working pressure and temperature and required dimensions to study convection. Porous media of different permeabilities were prepared using glass beads of different sizes. The experiments were carried out at 100 bar and 50 °C using a deionized water solution with Bromothymol blue (BTB) as pH indicator.

In the constructed Hele-Shaw 2D-cell, the cell volume was formed by two glass plates separated by an adjustable spacer. In the present study, the cell thickness was 5.0 mm in the main part of the cell volume. The high-pressure Hele-Shaw cell has made it possible to investigate CO₂-dissolution and mixing with water at pressures and temperatures realistic for CO₂-storage reservoirs in a porous medium for the first time.

CO₂ mixing and finger initiation in the water phase without the presence of porous media was an instantaneous process. The rate for CO₂ dissolution and mixing with water was found to increase with increasing permeability. The CO₂ dissolution pattern was found to depend on the permeability. Fingering of CO₂-rich high-density water was observed with the highly permeable porous medium. Piston-like displacement was observed in lower permeable porous medium.

当将CO ₂注入含水层时，CO ₂将溶解到水相中。由扩散引发的CO ₂溶解将增加水相的密度，从而开始CO ₂的对流。本文工作的目的是在实际储层条件（压力和温度）下直观地研究渗透率对超临界CO ₂与水对流混合的影响。这需要构建高压透明的Hele-Shaw池，该池允许可视化CO ₂传输，并开发了实验程序。

为了开发高压Hele-Shaw电池，进行了应力/应变计算和模拟，以选择最佳的建筑材料来满足实际的工作压力和温度以及研究对流所需的尺寸。使用不同大小的玻璃珠制备不同渗透性的多孔介质。使用溴代百里酚蓝（BTB）作为pH指示剂的去离子水溶液在100 bar和50°C下进行实验。

在构造的Hele-Shaw 2D细胞中，细胞体积由两块玻璃板形成，两块玻璃板之间用可调垫片隔开。在本研究中，细胞体积的主要部分的细胞厚度为5.0毫米。高压Hele-Shaw池使首次研究多孔介质中CO _2的溶解度和在与CO ₂储存库实际相适应的压力和温度下与水混合成为可能。

在不存在多孔介质的情况下，在水相中进行CO ₂混合和手指引发是一个瞬时过程。发现CO ₂溶解和与水混合的速率随着渗透率的增加而增加。发现CO ₂溶解模式取决于渗透率。用高渗透性多孔介质观察到富含CO _2的高密度水的指法。在较低渗透性的多孔介质中观察到活塞状位移。