Evaluating Containment Integrity and Fault Slip Risk for CO2 Storage in a Complex Tectonic Setting, India

Summary This study evaluates the containment integrity and fault slip risk for CO2 geological storage in the Naharkatiya field, Upper Assam Basin. Leveraging the region’s depleted hydrocarbon reservoirs, well-developed infrastructure, and subsurface datasets, the study supports Assam’s suitability for long-term CO2 sequestration. A comprehensive workflow integrates seismic data interpretation, structural mapping, and geomechanical modelling to assess the risk of fault reactivation and CO2 containment breach. Key reservoir formations demonstrate favourable porosity and permeability, with sealing provided by the regional shale and claystones. The study identifies complex fault systems, including northeast-southwest trending major and orthogonal minor faults, influencing reservoir compartmentalization and potential leakage pathways. Fault Slip Potential (FSP) analysis, conducted under varying CO2 and water injection scenarios, highlights that containment is most vulnerable under high-pressure conditions, especially with supercritical CO2 injection rates exceeding 50 million barrels per year. Shorter faults near injection sites exhibit elevated reactivation risks due to their unfavourable orientation within the local stress regime. The results emphasize the importance of optimizing injection strategies and continuous monitoring to maintain caprock integrity and mitigate fault reactivation. The findings contribute to de-risking CO2 storage projects in the structurally complex Upper Assam Basin and align with India’s climate change mitigation efforts.