Feasibility and Performance Evaluation of CO2-EWR Systems: The Simulation Study on CO2 Injectivity and Storage Capacity Enhancement

Abstract

The rapid increase in global warming due to greenhouse gas emission, accompanying the development of human civilization, has led to the establishment of the global common goal of achieving called Net-zero, by 2050. To reach this goal, several efforts are being made through the expansion of renewable energy and methods such as CCS (Carbon Capture and Storage). This study describes a simulation study aimed at improving the efficiency of CO₂ storage using the CO₂-EWR (Enhanced Water Recovery) technology, as well as an evaluation of its feasibility in the field, through indirect comparative analysis with pilot data.

The CO₂-EWR technology takes advantage of the concept that the pressure in the aquifer decreases due to the extraction of produced water, allowing for additional CO₂ injection into the aquifer due to the reduced pressure. In the field experiment, a steel pipe with a diameter of 0.2 m and a length of 5 m was filled with glass beads (70-110 µm) to simulate aquifer conditions. In the experiments, absolute permeability was measured, and 85 Bar of supercritical CO₂ was injected into the pipe, simulating aquifer conditions of 35°C and 80 Bar. And supercritical CO₂ flow rate at the breakthrough point at the back end of the pipe was measured. The absolute permeability, measured using Darcy’s law, was found to be approximately 6548 mD and CO₂ flow rate at the breakthrough point was 5.46 kg. The simulation modeling conditions involved filling a pipe of the same size with small size glass beads (40-70 µm) and injecting 40°C, 84 Bar supercritical CO₂ into a simulated environment of 40°C and 80 Bar, with a breakthrough point of supercritical CO₂ flow rate measured at 3.69 kg. Although a direct comparison between the field data and the modeling conditions is difficult due to differences in conditions, the higher permeability and injection pressure in the field data suggest meaningful results. Near future, direct comparisons of modeling results under identical conditions as the field site, along with additional CO₂-EWR tests, simulating various conditions, are expected to provide reasonable data. This data will contribute to optimizing the CO₂ injection efficiency and storage capacity, offering a guideline for field application.

 

Acknowledgement

This work was supported by Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government (MOTIE) (20212010200010, Technical development of enhancing CO₂ injection efficiency and increase in storage capacity)