Assessment of CO₂ Sequestration in a Stack Storage Complex in the San Juan Basin, NM Available to Purchase

Effective CO₂ sequestration requires not only minimizing carbon emissions but also optimizing storage efficiency while ensuring the integrity of storage sites. This research focuses on the assessment of CO₂ injection in a stack storage system, specifically targeting the Entrada (high-permeability) and Bluff (low-permeability) formations within the San Juan Basin. By leveraging a single well to inject CO₂ across multiple formations, the goal is to enhance storage efficiency, reduce the spatial extent of CO₂ plumes, and minimize the area requiring long-term monitoring.

A high-resolution hydrodynamic reservoir model was developed and validated using historical injection rates and pressure data from nearby saltwater disposal wells. This model was used to simulate 30 years of CO₂ injection, aiming to store 50MtCO_2f through a stacked storage configuration. Three well-completion strategies were explored: (1) a base case with injection into Entrada only, (2) a case with commingled injection into both formations through a single well, and (3) 6 scenarios using smart well-completion techniques to simultaneously inject CO₂ into the Entrada and Bluff formations at controlled rates. Different injection rates were tested to identify the best scenario that minimizes CO₂ plume size while meeting the storage target.

Simulation results from the base case of injecting into Entrada only revealed that at an injection rate of 80MMSCFD, 50MtCO₂ can be injected over 30 years. The commingled injection case showed that over 90% of injected CO₂ entered the Entrada formation, leading to larger plume size (64.69 square miles after 100 years of post-injection monitoring) and an expanded area requiring monitoring. In contrast, the optimized injection strategy, with CO₂ allocated at varying rates (25%, 31%, and 34% of the total injection rate of 80MMSCD) to the Bluff formation, resulted in the best scenario case significantly reducing the Entrada plume spatial extent by 22% while increasing the plume size in the Bluff formation by approximately 94%, accompanied by a 77% increment in the storage capacity. Ultimately, the best scenario reduced the total area requiring monitoring, demonstrating the effectiveness of a stack storage approach in controlling CO₂ migration and pressure fronts.

This study highlights the importance of optimizing CO₂ in stacked storage systems to maximize sequestration efficiency. By carefully managing injection rates, the spread of CO₂ plumes can be controlled, reducing monitoring costs and ensuring safe, long-term storage. The findings provide valuable insights for improving the practical implementation of CO₂ capture and storage projects using stack storage systems.