Risk-Based and Proportionate Measure, Monitoring and Verification (MMV) Plans That Meet Key Regulations

Abstract Carbon Capture and Storage (CCS) is a key technology for reducing CO2 emissions by storing captured CO2 in deep underground formations. However, the storage phase presents several technical risks. These include limited capacity for injected volumes, low injectivity (difficulty in injecting CO2), and the potential for CO2 to leak from the storage site. It is important to understand that CO2 storage is not simply the reverse of oil and gas production. CO2 is chemically and thermodynamically different from hydrocarbons and behaves unpredictably under varying subsurface conditions, especially when injection pressures rise beyond virgin pressures. Regulators around the world require risk-based Measurement, Monitoring, and Verification (MMV) plans. These plans must demonstrate that storage operators are responsible and fully prepared to detect, assess, and respond to any unexpected CO2 migration or signs of possible loss of containment. A key tool in developing a risk-based MMV plan is the Containment Risk Assessment (CRA). The CRA identifies potential leak pathways and evaluates the likelihood and impact of leaks. It supports the design of the MMV plan by focusing monitoring efforts on higher-risk areas. The MMV plan includes selected technologies for monitoring, implementation strategies, and clear response actions in case of a confirmed or suspected leak. CRA incorporates geological data, well information (existing and planned), and dynamic simulations to predict how CO2 and any displaced fluids may behave underground. It evaluates all possible leak paths, even unlikely ones, and identifies both physical containment barriers and mitigation options. These findings are organized using bowtie diagrams, which help visualize how risks are managed. They also highlight the need for procedural barriers, such as early detection protocols and corrective actions. Ultimately, regulators seek operators who can demonstrate they understand the risks and are prepared to manage them effectively, ensuring safe, long-term CO2 storage.