Experience with Using Controlled Source Electromagnetics (CSEM) for CCUS Monitoring and Future Applications

An electromagnetic (EM) geophysical survey using Controlled Source Electromagnetic (CSEM) methods was conducted in North Dakota, USA, to evaluate its feasibility for monitoring subsurface CO₂ fluid plumes. This study assesses the advantages, constraints, and necessary enhancements of both passive and active electromagnetic techniques in the context of carbon capture and storage (CCS). Surface log-scale resolution was successfully achieved, demonstrating the method's capability to delineate fluid plume boundaries and estimate fluid volumes with high accuracy. These findings underscore CSEM's ability to detect subtle resistivity changes associated with CO₂ saturation, an essential factor in monitoring fluid migration and ensuring storage integrity. A detailed petrophysical analysis supported the construction of a robust 3D anisotropic model, which accounted for heterogeneities in reservoir properties and included local noise assessments to optimize survey parameters and data quality. Integrating magnetic and electric field measurements proved crucial in enhancing spatial resolution and sensitivity to subsurface changes, facilitating precise characterization of geological formations and fluid distributions. Results confirmed the effectiveness of this integrative geophysical approach for dynamic reservoir monitoring, enabling time-lapse (4D) imaging to track plume evolution over time. The promising outcomes suggest significant potential for CSEM in ongoing and planned CO₂ storage projects, particularly for verifying containment, detecting leakage pathways, and informing injection strategies. Furthermore, the techniques and insights gained from this study hold broader implications for monitoring other subsurface energy storage systems, including underground hydrogen storage, recharge aquifers, and even geothermal reservoir development. As global interest in subsurface storage technologies grows, advanced EM methods like CSEM are poised to be pivotal in supporting sustainable and secure energy transition initiatives.