CO2 plume monitoring and injection optimization based on pathlines, source clouds and time clouds: Field application at the Illinois Basin-Decatur carbon sequestration project

The performance of CO₂ injection in geological carbon storage projects can be significantly influenced by the effects of gravity and subsurface heterogeneity, making effective monitoring and optimization essential. While streamlines are widely used to visualize fluid flow, they rely on instantaneous velocity fields and cannot account for dynamic conditions. To overcome this, we propose novel tools—pathlines, source clouds (streaklines), and time clouds (timelines)—to track CO₂ movement across varying flow fields, particularly during the post-injection stage when gravity effects dominate. These tools serve as a foundation for optimizing injection strategies to enhance storage efficiency.

Pathlines trace the trajectories of CO₂ particles over time, capturing dynamic flow field changes. Streaklines and timelines extend this by visualizing all particles emitted from a point or at a specific time, represented as source and time clouds in 3D. These tools enable precise visualization of CO₂ movement in the reservoir, critical for optimizing storage efficiency. Our optimization framework identifies optimal injection rates by equalizing arrival times, maximizing storage efficiency under operational constraints. Using analytical sensitivities, a sequential quadratic programming (SQP) algorithm minimizes arrival time variance from the perforation zones, providing a comprehensive and effective strategy for CO₂ injection optimization.

Applied to the Illinois Basin-Decatur Project (IBDP), our methods demonstrate improved plume visualization and optimization. Pathlines accurately represent plume distribution, while source and time clouds capture movement from perforations and front propagation. Optimizing injection rates across three perforation zones increased storage efficiency by 10.4 %, showcasing the effectiveness of this approach in advancing geological carbon storage projects.