Description of the Research Opportunity
Geologic sequestration of CO2 (GCS) into subsurface reservoirs can play an important role in limiting future emission of CO2 into the atmosphere (e.g., Benson and Cole, 2008). For GCS to become a viable option to reduce greenhouse gas emissions, large-volume injection of super-critical CO2 into deep sedimentary formations is required. However, hazards associated with injection of CO2 into deep formations require evaluation before widespread sequestration can be adopted safely (Zoback and Gorelick, 2012). One of these hazards is the potential to induce seismicity on pre-existing faults or fractures. If these faults or fractures are large and critically stressed, seismic events can occur with magnitudes large enough to pose a hazard to surface infrastructure and, possibly more critically, the seal integrity of the cap rock.
Forecasting seismicity rates and seismic hazard has become a viable tool for regulators and operators in assessing the potential impact of underground injection, mainly in the oil and gas realm. These tools are based on hydromechanical formulations that relate fluid injection to seismicity rate using rate-and-state formulations of failure in the basement rock (e.g. Norbeck and Rubinstein, 2018). The same methods can be employed in geologic carbon sequestration (GCS) settings to first order with little change in the underlying physics. Additionally, the extension from seismicity rate to standard seismic hazards computations is identical for the GCS settings (Rubinstein et al., 2021).
The noted change in forecasting seismic hazard in GCS settings from oil and gas settings is that not only are potentially damaging ground motions at the surface a concern, but the integrity of the sealing layer also is a major implementation concern as sequestered CO2 may escape the injection formation and eventually make its way into the atmosphere. Small magnitude seismicity near sealing layers can impose significant stresses that have the potential to lead to loss of sealing capacity on the sealing layer itself. Therefore, the development of peak stress criteria within the sealing layers, akin to peak ground motion models for surface damage, would mark a substantial improvement in the extension of seismic hazard forecasting in GCS.
We seek a Mendenhall Postdoctoral Fellow to advance the capability of forecasting seismicity rate and seismic hazard due to GCS. This work may broadly encapsulate geomechanical modeling work, seismic hazard analyses, ground motion derivations specific to GCS settings, and statistical seismology. The work ideally is carried out using a combination of the aforementioned activities and would yield important contributions to the safe adoption of GCS.
A successful proposal would develop new approaches to understanding the:
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relevant adaptation of subsurface pore pressure modeling for GCS including, for example, relative permeability and buoyancy effects;
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modeling of peak stresses in sealing layers and defining metrics can be included in hazard analyses for likely scenarios of seismicity;
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inclusion of GCS-specific modeling and ground motion metrics into seismic hazard analyses.
The proposed work would apply and develop innovative tools and methods that can be translated into field- and basin-wide analyses of seismic hazard associated with GCS. The methods and tools would vastly improve existing models of seismic hazard forecasting in GCS.
Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.
References:
Benson, S. and Cole, D.R. (2008) CO2 Sequestration in Deep Sedimentary Formations. Elements, 4, 325-331, http://dx.doi.org/10.2113/gselements.4.5.325
Norbeck,J. H., and Rubinstein, J. L. (2018) Hydromechanical earthquake nucleation model forecasts onset, peak, and falling rates of induced seismicity in Oklahoma and Kansas, Geophys. Res. Lett. 45, no.7, 2963–2975, doi: https://doi.org/10.1002/2017GL076562
Rubinstein, J.L., Barbour, A.J., and Norbeck, J.H. (2021) Forecasting Induced Earthquake Hazard Using a Hydromechanical Earthquake Nucleation Model. Seismological Research Letters,92 (4), 2206–2220, doi: https://doi.org/10.1785/0220200215
Zoback, M.D. and Gorelick, S.M. (2012) Earthquake triggering and large-scale geologic storage of carbon dioxide, Proc Natl Acad Sci USA 109, doi: https://doi.org/10.1073/pnas.1202473109
Proposed Duty Station(s)
Pasadena, California
Moffett Field, California
Areas of PhD
Seismology, geology, geophysics, geomechanics, civil engineering, petroleum engineering, material sciences or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).
Qualifications
Applicants must meet one of the following qualifications: Research Geologist, Research Geophysicist, Research Hydrologist, Research Petroleum Engineer, Research Physicist, Research Geodesist, Research Engineer, Research Environmental Engineer
(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)
