Experimental Investigation on CO2-Sensitive Gel-Type Sealant for Sealing Leaky Carbon Sequestration Wellbores

Abstract Potential upward leakage of CO2 and reservoir fluid within a leaky sequestration well poses potential environmental and economic risks. This study explores the latest methods for fixing wells in challenging situations where CO2 is present. An in-depth series of tests was carried out to examine how a special methyl methacrylate-based gel, modified to react to CO2, behaves and functions in carbon capture areas. The experiment looked at how much the gel expanded over time using laser profilometry to measure its growth under various conditions. The study also measured the gel's properties and its ability to seal when there was no CO2 present by comparing the behavior of different concentrations of sealant. Tests using thermogravimetric analysis and thermo-stability measurements were carried out to understand the sealant's reactions at higher temperatures, as well as carbon dioxide leak tests under downhole conditions, were also part of the research. The study found that the gel's effectiveness in sealing wells is influenced by several factors including exposure time, concentration of gel (monomer), substance used to trigger the reaction (CO2, for instance), and temperature. The research demonstrated that the gel-based sealant was able to expand up to 20 times its original size when exposed to CO2 and moisture. Additionally, the sealant showed a high capacity to resist, maintain its structure, and work at high temperatures (up to 140°C) and CO2 pressure (approximately 1550 psi). Moreover, experiments suggested that the sealant naturally formed a seal with CO2 over time, reducing the chance of leaks and completely stopping them at the right concentration.