Technology Focus: Reservoir Surveillance (September 2025)

_ In carbon capture and storage (CCS), injecting CO2 is only the beginning. Ensuring it remains securely stored underground—undisturbed and undetected in the atmosphere—is the true challenge. At depths of thousands of feet, where extreme pressures and temperatures prevail, tracking CO2 movement becomes a complex task. In this environment, reservoir surveillance is not just a support activity—it is fundamental to the credibility and scalability of CCS. To meet these demands, engineers and scientists are deploying a new generation of surveillance solutions that blend physics-based models, real-time sensing technologies, and machine learning. In paper SPE 225486, controlled source electromagnetics is applied to detect subtle plume migration and saturation changes, offering a powerful complement to seismic data. Paper SPE 223005 highlights the use of distributed fiber-optic sensing—distributed acoustic, distributed temperature, and strain—to monitor injection behavior in carbonate aquifers where conventional imaging falls short. Paper SPE 224150 introduces a machine-learning-based proxy model trained on simulation data, enabling rapid optimization of injection strategies and predictive tracking of pressure and saturation for improved storage performance. These innovations are transforming subsurface monitoring into a proactive, continuous, and intelligence-driven function—one capable of building regulatory confidence, operational certainty, and public trust. As of mid-2025, more than 50 CCS facilities are capturing approximately 51 million tons of CO2 annually, with over 600 additional projects in the pipeline. Yet the success of these efforts rests on a single truth: If we cannot monitor it, we cannot manage it. Surveillance is no longer a technical afterthought—it is the foundation of long-term CCS integrity. Summarized Papers in This September 2025 Issue SPE 225486 - Controlled-Source Electromagnetics Provide Promise for CCS Applications by Panagiotis Kirmizakis, King Fahd University of Petroleum and Minerals, et al. SPE 223005 - Fiber Optics Monitor CO2 Injection in Carbonate Saline Aquifer by Jane E. Mason, ADNOC, et al. SPE 224150 - ML-Based Co-Optimization Framework Improves CO2 Sequestration and Oil Recovery by Kassem Alokla, Texas A&M University, et al. Recommended Additional Reading at OnePetro: www.onepetro.org. SPE 222348 - Chemical Tracer for Soil CCS Monitoring Application: Monitoring CO2 Storage in Saline Aquifers Using Advanced Chemical Tracer and Detection Technology by Hiyam Al Muntheri, Abu Dhabi National Oil Company, et al. OMC 2025-642 - Ravenna CCUS Project: Fiber-Optic Deployment for Measurement, Monitoring, and Verification Purposes by Sara Moriggi, Eni, et al. SPE 220695 - Plastic Deformation and Resulting Enhancement in Caprock-Failure Limit by Yidi Wu, The Pennsylvania State University, et al.