A Methodology for Assessing and Improving the Capacity of CO2 Injection in Saline Aquifers

Abstract

Abstract Carbon capture and storage (CCS) is recognized as one of the key strategies to mitigate greenhouse gas emissions and tackle climate change. In CCS, carbon dioxide (CO2) is captured from industrial processes, compressed, and injected into geological formations, such as saline aquifers, for long-term storage. However, the success of CCS depends on the capacity of geological formations to store CO2 safely and securely. As saline aquifers form one of the potential known geological storage, evaluating the capacity reliably early in time is valuable. This paper presents a methodology for assessing the CO2 capacity using a material balance approach and comparing the results with dynamic simulation in order to define if an early reliable estimation is possible. The methodology includes four main steps: (1) data collection and analysis, (2) reservoir characterization understanding, (3) modelling and simulation, and (4) sensitivity analysis and optimization. The first step involves collecting and analysing data on the reservoir and injection operations, such as geological and hydrogeological parameters, reservoir pressure, and injection rate. The second step focuses on characterizing the saline aquifer using geological data. The third step involves developing a material balance model to simulate the injection and storage of CO2 in the aquifer, then compared to the dynamic simulation. The fourth step involves performing sensitivity analysis and optimization to evaluate the impact of different parameters on CO2 storage capacity, including operating condition, injection pressure and rate, then the optimum strategy for improving the injection efficiency can be identified. The proposed methodology was applied, and the results showed that the material balance model could help to predict the behaviour of CO2 storage capacity at an early stage with reasonable and acceptable accuracy. Sensitivity analysis on reservoir permeability, injection rate, and reservoir pressure has been conducted and the results are discussed in this paper. The optimization analysis identified that increasing the injection rate and maintaining high reservoir pressure could significantly improve CO2 storage capacity. In conclusion, the proposed methodology provides a comprehensive and systematic approach for assessing the capacity of CO2 in saline aquifers at an early stage as well as the potential solutions to improve the capacity.