The project awarded to Virginia Tech’s Virginia Center for Coal and Energy Research (VCCER) will evaluate unconventional geologic storage options in the Central Appalachian Basin (Figure 1). Previous RCSP research studies have identified promising storage reservoirs for CO2 storage (conventional and unconventional) in central Appalachia and tested coal seam storage through a nearly 1,000 metric ton field validation test. Results from these studies form the basis to inject up to 20,000 metric tons into unconventional geologic formations in the Oakwood coal bed methane (CBM) field in Buchanan County, Virginia. Recent evaluations indicate the potential for promising opportunities for carbon storage are Pennsylvanian age coal seams and Devonian age organic-rich shales.
This project will design and implement characterization, injection, and monitoring activities to test unconventional formations (coal and organic shales) ability to store CO2 economically and safely as well as track the migration of CO2 throughout the injection and post-injection phases. In addition, this research will test the injectivity of CO2 into unmineable coal seams and the potential for enhanced coalbed methane recovery (ECBM) by stressing the coal under continuous CO2 injection for a period of one year. Storage of CO2 in developed and depleted organic shale layers, such as the Marcellus, Lower Huron and Chattanooga, will also be investigated with a targeted CO2 injection test into a depleted shale gas well. Different reservoir models will be used before, during, and after injection to simulate injectivity and track plume behavior. Multiple MVA technologies will be used to obtain critical data needed to perform tracking and characterize the behavior of the CO2 coal seam interaction. Overall monitoring of plume migration, injection operations, and CO2 injectate/formation reactions will be accomplished using downhole seismic, advanced geophysical logging, gas desorption and adsorption analysis, and analyzing gas and water from nearby recovery wells. Additional leakage monitoring will be performed using the near surface techniques of soil gas and soil flux measurements, tracer and isotope studies, vegetative stress and geo-microbiology studies, and ambient CO2 and methane (CH4) analysis.
The U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) is supporting small-scale field projects (injection of less than 500,000 metric tons of CO2 per year) to explore various geologic CO2 storage opportunities within the United States and portions of Canada. DOE’s small-scale field projects efforts are designed to validate the CO2 storage capability in various depositional systems within the potential storage types. Understanding these different storage classes provides insight into how their depositional systems influence current fluid flow within these reservoirs and how stored CO2 would be anticipated to migrate through the storage reservoir for a larger volume commercial scale project. The data gathered during these small-scale field projects provide valuable information about specific formations that have not been extensively evaluated for CO2 storage potential. DOE’s Carbon Storage Program strategy includes an established set of field test objectives applicable to small-scale projects, including (1) confirming storage resources and injectivity; (2) validating the effectiveness of simulation models and monitoring, verification, and accounting (MVA) technologies; (3) developing guidelines for well completion, operations, and abandonment in order to maximize CO2 storage potential and mitigate any potential release; (4) developing public outreach plans and communicating the benefits of carbon capture, utilization, and storage (CCUS) to stakeholders; and (5) satisfying the regulatory permitting requirements for small-scale CCUS projects.
Existing small-scale field projects have been conducted by the Regional Carbon Sequestration Partnerships (RCSP) during their Validation Phase. These small-scale tests have provided valuable data, but complex issues surrounding the processes associated with geologic CO2 storage and monitoring across various types of formations and depositional environments still remain. Due to the need to further understand CO2 behavior in various formations and depositional environments, NETL’s Carbon Storage Program is supporting additional research to augment the information gathered during the Validation Phase RCSP small-scale field projects. Virginia Tech is evaluating the long-term storage potential of CO2 in coal seams and organic shales by injecting up to 20,000 metric tons of CO2 into these unconventional reservoirs in central Appalachia. The project will also evaluate enhanced coalbed methane extraction (ECBM) applications during CO2 injection activities.
This effort supports the NETL Carbon Storage Program goals described in the Technology Program Plan. Specifically, it supports goals for small-scale injection studies that include:
Confirming storage resources and injectivity estimates for coal and shale storage target formations.
Validating the effectiveness of simulation models and monitoring, verification, and accounting (MVA) technologies to (1) predict and measure CO2 movement within geologic storage formations and (2) confirm the integrity of the seal formations that prevent the upward movement of CO2.
Developing guidelines for well completion, operations, and abandonment in order to maximize CO2 storage potential and mitigate any potential release.
Developing public outreach plans and communicating the benefits of CCUS to various stakeholders.
Satisfying the regulatory permitting requirements for small-scale CCUS projects.
Gathering information to improve estimates for storage capacity that could be used to update regional and national storage resource and capacity estimates.
The benefit of this research lies in proving the storage potential of coal seams with ECBM and other stacked unconventional formations in central Appalachia. Many of the CBM operations in the Central Appalachian Basin are approaching maturity, thus providing large reservoirs suitable for CO2 storage. Carbon dioxide injection into coal seams could increase CBM reserves by 20 to 40 percent while concurrently increasing the storage capacity for large volumes of CO2, however further understanding the effects of CO2 injection on coalseam injectivity and methane production is critical.
This project has been designed to reduce the uncertainties associated with long-term CO2 storage options in coal seams, developed organic shales, and depleted organic shales. This will be accomplished by designing and implementing characterization, injection, and monitoring activities to test unconventional storage formations in central Appalachia (Figure 1) and tracking the migration of CO2 throughout the injection and post-injection phases. The results of the project will help researchers better understand the effect of matrix swelling—caused by adsorption of CO2 on the coal surface—on injectivity and ECBM while providing much needed information on other unconventional reservoir options.
The data gathered as part of this research effort and pilot study will be shared with the Southeastern Carbon Sequestration Partnership (SECARB), integrated into the National Carbon Sequestration Database and Geographic Information System (NATCARB), and integrated into the U.S. 2012 Carbon Utilization and Storage Atlas.
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