Chapter 10 - CO2 Storage in Deep Saline Aquifers

Abstract

CO2 geological storage is a promising means of mitigating CO2 emissions, and deep saline aquifers appear to hold the largest potential storage capacity. Large-scale injection of CO2 into saline aquifers will induce a variety of coupled physical and chemical processes including multiphase fluid flow, solute transport, and chemical reactions between fluids and formation minerals. Thermodynamic and dynamic investigations are needed to study the sequestration capacity, CO2 leakage, and environmental impacts. Meanwhile, co-injection of CO2 with impurities may substantially reduce the capture and sequestration costs, but it is necessary to investigate the effect of impurities on both thermodynamic and dynamic models. In this chapter, CO2 capture and storage is briefly introduced. The development of the thermodynamic model representing phase equilibrium and thermodynamic properties for CO2-storage-related systems is reviewed, and the model based on Statistical Associating Fluid Theory (SAFT) is introduced in detail. Thermodynamic properties of density and equilibrium composition for CO2-storage-related systems are presented with an SAFT-based model, and the effect of impurities is investigated. Future work to extent the SAFT-based model to represent viscosity, interfacial properties, as well as the fluid behavior on confined pores is discussed. It is expected that the model can be further incorporated into process models to provide a reliable long-term prediction pertaining to geological carbon sequestration, such as sequestration capacity, CO2 leakage, environmental impacts, and so forth.