Optimizing CO 2 -Water Injection Ratio in Heterogeneous Reservoirs: Implications for CO 2 Geo-Storage

Emad A. Al-Khdheeawi ()
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Emad A. Al-Khdheeawi: Oil and Gas Engineering Department, University of Technology-Iraq, Baghdad 10066, Iraq

Energies, 2024, vol. 17, issue 3, 1-14

Abstract: The performance of carbon geo-sequestration is influenced by several parameters, such as the heterogeneity of the reservoir, the characteristics of the caprock, the wettability of the rock, and the salinity of the aquifer brine. Although many characteristics, like the formation geology, are fixed and cannot be altered, it is feasible to choose and manipulate other parameters in order to design an optimized storage programme such as the implementation of CO 2 injection techniques, including continuous injection or water alternating CO 2 , which can significantly increase storage capacity and guarantee secure containment. Although WAG (water-alternating-gas) technology has been widely applied in several industrial sectors such as enhanced oil recovery (EOR) and CO 2 geo-sequestration, the impact of the CO 2 -to-water ratio on the performance of CO 2 geo-sequestration in heterogeneous formations has not been investigated. In this study, we have constructed a 3D heterogeneous reservoir model to simulate the injection of water alternating gas in deep reservoirs. We have tested several CO 2 -water ratios, specifically the 2:1, 1:1, and 1:2 ratios. Additionally, we have estimated the capacity of CO 2 trapping, as well as the mobility and migration of CO 2 . Our findings indicate that injecting a low ratio of CO 2 to water (specifically 1:2) resulted in a much better performance compared to situations with no water injection and high CO 2 -water ratios. The residual and solubility trappings were notably increased by 11% and 19%, respectively, but the presence of free mobile CO 2 was reduced by 27%. Therefore, in the reservoir under investigation, the lower CO 2 -water ratio is recommended due to its improvement in CO 2 storage capacity and containment security.

Keywords: WAG; CO 2 storage; heterogeneity; residual trapping; solubility trapping (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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