Experimental Investigation on Salt Precipitation Behavior during Carbon Geological Sequestration: Considering the Influence of Formation Boundary Solutions

The issue of salt precipitation during CO2 geological storage in saline aquifers has presented significant challenges to the injectivity of current CO2 geological storage projects. Numerous research efforts have been dedicated to investigating this problem; however, many laboratory studies have overlooked the influence of boundary conditions on the solution supply. This paper addresses this gap by conducting a pore-scale experimental study incorporating solution supply in a specially designed micromodel. The results reveal that in the absence of a solution supply, salt precipitates in a dendritic structure and is spatially dispersed, which only marginally decreases the injectivity. In contrast, under conditions with solution supply, different salt precipitation behaviors are observed based on the injection rate of CO2. At low CO2 injection rates, a salt cluster precipitates at the inlet, and the combination of significant porosity reduction and the formation of wet salt leads to a severe decrease in permeability. However, increasing the injection rate prevents salt accumulation at the inlet; instead, a U-shaped band of salt forms on both sides of the mainstream area and the outlet. These research findings shed light on the influence of solution supply boundary conditions on salt precipitation behavior and provide crucial guidance for effectively managing salt-related challenges in CO2 geological storage projects.