Abstract
As the global energy perspective shifts towards renewable sources, sustainable energy storage solutions become crucial for ensuring consistent energy supply. Underground storage systems of gases show a promising solution for such demands, where depleted oil & gas reservoirs, salt caverns and saline aquifers are the main focus of such development efforts.This study explores the potential of saline aquifers for subsurface storage of carbon dioxide (CO2), focusing on the challenges posed by salt precipitation in the near-wellbore area. A phenomenon that can significantly reduce the permeability and porosity of the aquifer, decreasing storage efficiency and potentially causing mechanical damage of the formation. The primary objective is to investigate how near-wellbore dry-out and salt precipitation affect the performance and reliability of CO2 storage in saline aquifers.
Experimental analyses were conducted to observe the effects of varying brine concentrations on permeability and porosity. Core plugs from Berea sandstone and Bentheimer sandstone were saturated with different Sodium Chloride brine concentrations, then subjected to dry in oven to replicate the conditions of gas injection cycles and salt precipitation in the aquifer. The results indicate that increased brine concentrations lead to higher salt precipitation, which clogs pore spaces and reduces permeability, thereby impacting injectivity. Berea sandstone, with smaller pore spaces, shown a more significant reduction in permeability compared to Bentheimer sandstone. A critical threshold brine concentration was identified at 10-12 wt.%, beyond which permeability drastically declines, indicating a significant reduction in injectivity.
The study emphasizes the importance of understanding the rock’s microscopic structure and petrophysical properties for predicting and managing the impacts of salt precipitation on CO2 injectivity and storage. Recommendations for further research include experimental studies on the microscopic level of rock formations, water permeability experiments, and the use of reservoir simulation software for more accurate predictions. These insights aim to contribute to more effective CO2 storage strategies, as well as other potential gases such as Hydrogen or Natural gas, ultimately helping in mitigating global warming and providing long-term energy storage solutions and sustainable energy supplies.
Date of Award | Sept 2024 |
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Original language | English |
Supervisor | Christina Toigo (Supervisor) |