DOE partnered with The Ohio State University (OSU) to conduct research that focuses on enhancing geophysical methods to better characterize subsurface geologic conditions and monitor the effects of CO2 injection. Subsurface seismic and electromagnetic techniques are the only remote detection methods that can provide a detailed image of the subsurface. OSU’s efforts focused on improving the interpretation methods for subsurface seismic and electromagnetic (EM) techniques to enhance CO2 plume tracking. The primary scope of this research has been to generate three dimensional (3-D) models (crosshole and surface models) for both electromagnetic and seismic methods for the purpose of tracking CO2 at injection sites (Figure 1). Formation density and seismic return velocity are the key parameters required for testing and modeling seismic measurements. Conductivity and electric permittivity of the geology and the injected CO2 are critical parameters of the model variation for the electromagnetic measurements. The resultant models based on these data were then analyzed to determine the detection limits for geophysical imaging, using high frequency electromagnetic and seismic measurements. These models are capable of optimizing the spatial distribution of wellbores for CO2 plume tracking based on site-specific geologic data.
OSU has developed a graphical user interface-program called GphyzCO2 for the purpose of optimizing project site monitoring, verification, and accounting plans to track CO2 plumes. Program outputs were used to help aid the design of cross-hole, hole-to-surface, and geophysical surveys for the purpose of monitoring CO2 injection sites. The program is capable of determining the optimum number and location of wells necessary to approximate the extent of CO2 plume migration and displaying data in a three dimensional format.
The overall goal of the Department of Energy’s (DOE) Carbon Storage Program is to develop and advance technologies that will significantly improve the effectiveness of geologic carbon storage, reduce the cost of implementation, and prepare for widespread commercial deployment between 2020 and 2030. Research conducted to develop these technologies will ensure safe and permanent storage of carbon dioxide (CO2) to reduce greenhouse gas (GHG) emissions without adversely affecting energy use or hindering economic growth.
Geologic carbon storage involves the injection of CO2 into underground formations that have the ability to securely contain the CO2 permanently. Technologies being developed for geologic carbon storage are focused on five storage types: oil and gas reservoirs, saline formations, unmineable coal seams, basalts, and organic-rich shales. Technologies being developed will work towards meeting carbon storage programmatic goals of (1) estimating CO2 storage capacity +/- 30 percent in geologic formations; (2) ensuring 99 percent storage permanence; (3) improving efficiency of storage operations; and (4) developing Best Practices Manuals. Developing and deploying these technologies on a large scale will require a significantly expanded workforce trained in various carbon capture and storage (CCS) technical and non-technical disciplines that are currently under-represented in the United States. Education and training activities are needed to develop a future generation of geologists, scientists, and engineers who possess the skills required for implementing and deploying CCS technologies.
The National Energy Technology Laboratory (NETL), through funding provided by the American Recovery and Reinvestment Act (ARRA) of 2009, manages 43 projects that received more than $12.7 million in funding that focus on conducting geologic storage training and support fundamental research projects for graduate and undergraduate students throughout the United States. The training and projects can be categorized under one or more of the DOE Carbon Storage Program’s five Technology Areas: (1) Geologic Storage and Simulation and Risk Assessment (GSRA), (2) Monitoring, Verification, Accounting (MVA) and Assessment, (3) CO2 Use and Re-Use, (4) Regional Carbon Sequestration Partnerships (RCSP), and (5) Focus Area for Sequestration Science. This training effort is conducting research that can be used to characterize geologic formations and track CO2 movement in the subsurface as part of MVA operations.
The project developed a new software tool to design and execute surface and downhole geophysical information to provide definitive evaluation and monitoring tools for CCS sites. The tool better estimates CO2 storage capacity prior to injection operations and helps to ensure the goal of 99 percent CO2 storage permanence. The project also provided training opportunities for students to gain knowledge in CCS, to contribute to the human capital needed for large-scale CCS. By addressing MVA issues in the context of geologic reservoirs, a vital contribution has been made to the scientific, technical, and institutional knowledge base needed to cultivate a trained work force with skill sets in geology, geophysics, geomechanics, geochemistry, and reservoir engineering. Ultimately, OSU provided practical guidelines for use of geophysical imaging techniques at CO2 injection sites, and provided easy to use geophysical evaluation tools for researchers and stakeholders.
In addition to training students in CCS-related technology areas, the main purpose of this investigation was to develop a 3D software package that is able to:
Provide a quantifiable and verifiable means to establish geophysical methods for characterizing the background (pre-injection) geologic features of a CO2 injection site using seismic, EM and borehole methods.
Determine the sensitivity of geophysical methods to monitor changes in a plume’s distribution in the subsurface and coincident changes in the geologic regime over time in order to ensure accurate storage capacity estimates and CO2 storage permanence using data from a CO2 storage site to design injection models and simulate various injection and monitoring scenarios.
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