Safe and permanent storage is of the upmost importance and in order to achieve the goals of the program, the research focus area, Simulation and Risk Assessment, was created. Research in this focus area is an integrated effort to develop advanced simulation models of the subsurface and integrate the results into a risk assessment that includes both technical and programmatic risks.  As the simulation models are refined with new data, the uncertainty surrounding the identified risks decreases, in turn providing a more accurate risk assessment and mitigation plan for each project site.

Simulation Models
Existing numerical models that simulate geochemical, mechanical, and flow behavior of geologically-stored CO₂ are limited by scale and coupled effects occurring in geologic formations. Recently, significant progress has been made in the application of commercial simulators from the oil and gas industry for CO₂ storage. In addition, several models have been developed specifically for storage of CO₂ in saline formations and coal seams. Development of refined and coupled geochemical, mechanical, and flow models will better predict design and implementation of CCS field projects that increase effective use of storage capacity, injectivity, and containment.

Research will continue to develop innovative, advanced simulation models that can be readily integrated with advanced MVA technologies and risk assessment protocols. These models will include full coupling of multiple physical and chemical processes and describe the effects of the coupled processes on CO₂ transport. Some of these physical and chemical processes include:

• Geochemical processes (subsurface chemical reactions among CO₂, groundwater/brine, and rock)
• Geomechanical processes (how faults and fractures affect fluid pressure and CO₂ migration, and the converse of fluid pressure inducing rock deformation)
• Heat processes (temperature changes induced by CO₂ injection, associated CO₂ phase changes and chemical reactions)
• Fluid flow processes

Risk Assessment
Risk assessment and management for CO₂ sequestration efforts generally include two primary aspects: (1) programmatic risks (including resource and management risks) that may inhibit project progress or costs and (2) sequestration (technical) risks inherent to the scientific and engineering objectives of a sequestration project. For CO₂ sequestration, programmatic risks are dictated in part by the technical risks and vice-versa. For example, the risk associated with long-term financing of a CO₂ sequestration effort (a programmatic risk) is linked to some extent with the risk of excessive release of CO₂ through fractures in the geologic formation in which it is stored (a technical risk).  For a CO₂ sequestration effort, a useful risk assessment should:

• Identify all vulnerabilities associated with the effort
• Estimate the likelihood of damage associated with each vulnerability
• Estimate the costs of recovery from the damage
• Identify and summarize possible protective measures and their costs  
• Estimate savings that may result from better protective measures

There are several key technical risk features, events and processes for geologic CO₂ storage and these include:

• The release of CO₂ from its storage location (e.g., via wellbores, faults or fractures, etc.)
• Potential injection pressure increases or seismic events
• Gravity-driven CO₂ movement or residual trapping
• Displacement of brine or other fluids

A comprehensive risk assessment program will typically involve assembling a working group of scientists, engineers, and administrators to track details of both programmatic and technical sequestration risks and to develop risk mitigation approaches in real-time during project execution. Both qualitative and quantitative protocols will be developed to ensure the safe and permanent storage of CO₂.