Carbon dioxide injection into deep saline aquifers is governed by a number of physico-chemical processes including mineral dissolution and precipitation, multiphase fluid flow, and capillary trapping. These processes can be coupled; however, the impact of fluid–rock reaction on the multiphase flow properties is difficult to study and is not simply correlated with variations in porosity. We observed the impact of rock mineral dissolution on multiphase flow properties in two carbonate rocks with distinct pore structures. Observations of steady-state $$\hbox {N}_2$$ N 2 –water relative permeability and residual trapping were obtained, along with mercury injection capillary pressure characteristics. These tests alternated with eight stages in which 0.5% of the mineral volume was uniformly dissolved into solution from the rock cores using an aqueous solution with a temperature-controlled acid. Variations in the multiphase flow properties did not relate simply to changes in porosity, but corresponded to the changes in the underlying pore structure. In the Ketton carbonate, dissolution resulted in an increase in the fraction of pore volume made up by the smallest pores and a decrease in the fraction made up by the largest pores. This resulted in an increase in the relative permeability to the nonwetting phase, a decrease in the relative permeability to the wetting phase, and a modest, but systematic decrease in residual trapping. In the Estaillades carbonate, dissolution resulted in an increase in the fraction of pore volume made up by pores in the central range of the initial pore size distribution, and a corresponding decrease in the fraction made up by both the smallest and largest pores. This resulted in a decrease in the relative permeability to both the wetting and nonwetting fluid phases and no discernible impact on the residual trapping. In summary, the impact of rock matrix dissolution will be strongly dependent on the impact of that dissolution on the underlying pore structure of the rock. However, if the variation in pore structure can be observed or estimated with modelling, then it should be possible to estimate the impacts on multiphase flow properties.

中文翻译：

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矿物溶解对两种碳酸盐岩中排水相对渗透率和残余捕集的影响

二氧化碳注入深部咸水层受许多物理化学过程的控制，包括矿物溶解和沉淀、多相流体流动和毛细管捕集。这些过程可以耦合；然而，流体-岩石反应对多相流动特性的影响很难研究，并且不仅仅与孔隙度的变化相关。我们观察了岩石矿物溶解对两种具有不同孔隙结构的碳酸盐岩的多相流特性的影响。获得了稳态$$\hbox {N}_2$$ N 2 - 水相对渗透率和残余捕集的观察结果，以及压汞毛细管压力特性。这些测试交替进行八个阶段，其中 0. 使用温控酸的水溶液将 5% 的矿物从岩芯均匀地溶解到溶液中。多相流动特性的变化不仅与孔隙度的变化有关，而且与底层孔隙结构的变化有关。在酮碳酸盐中，溶解导致由最小孔隙组成的孔隙体积分数增加，由最大孔隙组成的分数减少。这导致非润湿相的相对渗透率增加，润湿相的相对渗透率降低，以及残余捕集的适度但系统的减少。在 Estaillades 碳酸盐中，溶解导致由初始孔径分布中心范围内的孔构成的孔体积分数增加，并且由最小和最大孔构成的分数相应减少。这导致润湿和非润湿流体相的相对渗透率降低，并且对残余捕集没有明显影响。总之，岩石基质溶解的影响将在很大程度上取决于溶解对岩石下伏孔隙结构的影响。但是，如果可以通过建模观察或估计孔隙结构的变化，则应该可以估计对多相流动特性的影响。这导致润湿和非润湿流体相的相对渗透率降低，并且对残余捕集没有明显影响。总之，岩石基质溶解的影响将在很大程度上取决于溶解对岩石下伏孔隙结构的影响。但是，如果可以通过建模观察或估计孔隙结构的变化，则应该可以估计对多相流动特性的影响。这导致润湿和非润湿流体相的相对渗透率降低，并且对残余捕集没有明显影响。总之，岩石基质溶解的影响将在很大程度上取决于溶解对岩石下伏孔隙结构的影响。但是，如果可以通过建模观察或估计孔隙结构的变化，则应该可以估计对多相流动特性的影响。