In the quest to secure the integrity of carbon capture and storage (CCS) wells, researchers have made a significant stride by investigating the intricate behavior of well interfaces under the coupled effects of temperature, fluid flow, and mechanical stress. Lee J. Hosking, a researcher from Brunel University of London, has led a study that delves into the damage modeling of CO2 injection well interfaces, shedding light on critical factors that could influence the future of CCS technologies.
The study, published in the journal ‘Deep Underground Science and Engineering’ (which translates to ‘Deep Underground Science and Engineering’), employs a sophisticated model of thermo-poroelasticity combined with interface damage mechanics. This approach allows for a comprehensive analysis of the casing–cement and cement–formation interfaces, which are crucial for maintaining well integrity during CO2 injection.
Hosking and his team utilized cohesive interface elements and a bilinear traction–separation law to describe the interfaces, enabling them to simulate the complex interactions that occur during CO2 injection. “Understanding the behavior of these interfaces is paramount for ensuring the long-term safety and efficiency of CCS operations,” Hosking explained. “Our research highlights the importance of considering initial defects and the evolution of damage in these critical components.”
The simulations revealed that tensile radial stress developed at both the casing–cement and cement–formation interfaces under the conditions studied. Notably, the hoop stress in the cement sheath remained compressive after 30 days of CO2 injection, but its magnitude decreased at lower injection temperatures. This finding suggests a heightened risk of tensile stress and radial cracking as the injection temperature is reduced.
One of the most compelling aspects of the study is the impact of pre-existing defects on well integrity. The research demonstrated that the inclusion of a pre-existing defect led to earlier damage initiation and a significantly larger microannulus. “The presence of initial defects can substantially alter the damage progression and the overall integrity of the well,” Hosking noted. “This underscores the need for meticulous inspection and maintenance of CO2 injection wells to prevent potential failures.”
The commercial implications of this research are profound for the energy sector. As CCS technologies become increasingly vital for reducing carbon emissions, ensuring the integrity of injection wells is crucial for both safety and economic viability. The findings from Hosking’s study provide valuable insights that could shape future developments in well design, construction, and monitoring practices.
By emphasizing the importance of accounting for initial defects and damage evolution, this research offers a roadmap for enhancing the reliability and performance of CCS wells. As the energy sector continues to evolve, such advancements will be instrumental in achieving sustainable and efficient carbon management solutions.