Carbon dioxide (CO2) injected into geologic reservoirs for long-term sequestration, or the brine it displaces, may leak through natural or manmade pathways. Using a leakage estimation model, we simulated fluid leakage from a storage reservoir and its migration into overlying formations. The results are discussed in the context of policies that seek to assure long-term sequestration and protect groundwater. This work is based on a case study of CO2 injection into the Mt. Simon sandstone in the Michigan sedimentary basin, for which we constructed a simplified hydrologic representation of the geologic formations. The simulation results show that (1) CO2 leakage can reach an aquifer containing potable water, but numerous intervening stratigraphic traps limit the rate to be orders of magnitude less than the rate of leakage from the storage reservoir; (2) U.S. Department of Energy guidelines for storage permanence allow for more leakage from larger injection projects than for smaller ones; (3) well leakage permeability is the most important variable in determining leakage processes and substantial leakage requires that numerous wells leaking with the anomalously high permeability of 10-10m2; and (4) leakage can reduce the U.S. Environmental Protection Agency's Area of Review.
Bibliographical noteFunding Information:
We thank David Bael, Joseph Dammel, Joshua Donato, Nathan Paine, and Mina Rahimi for their research assistance, Melisa Pollak for helping with data collection and analysis for the 3-D model, and Thomas Elliot and Bin Guo for getting ELSA modeling initiated. We also thank the anonymous reviewers whose comments and insights helped us to improve the paper. This research was funded by the Department of Energy, Office of Fossil Energy , under grant DE-FE-0000749 , and by the National Science Foundation under Sustainable Energy Pathways grant ( 1230691 ) and under grant CMMI-0919140 . J.M.B. developed the methodology, acquired data, conducted analyses, analyzed results, and wrote the paper. E.J.W. wrote the paper. J.P.F. wrote the paper. C.A.P. analyzed results and wrote the paper. Disclaimer: neither the U.S. government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation or favoring by the U.S. governing or any agency thereof. The views and opinions of authors expressed herein, do not necessarily state or reflect those of the U.S. government or any agency thereof.
- Area of Review
- CCUS policy
- Carbon sequestration
- Geologic storage