PEER has published Report No. 2025/14, Fragility Curves for Gas Leakage Through Caprock of the Underground Gas Storage Reservoir in California. The report was authored by Yingqi Zhang, Jonny Rutqvist, Preston Jordan, and William Foxall, of the Energy Geosciences Division, Lawrence Berkeley National Laboratory.
Access the report and 2 page summary. Access the full listing of PEER reports.
Abstract
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project conducted by the Pacific Earthquake Engineering Research Center (PEER) with the Lawrence Berkeley National Laboratory (LBNL) and funded by the California Energy Commission (CEC). The overall project is titled “Performance-based Earthquake Engineering Assessment Tool for Natural Gas Storage and Pipeline Systems” henceforth referred to as the “OpenSRA Project”
The overall goal of the OpenSRA project is to create an open-source research-based seismic risk assessment tool for natural gas infrastructure that can be used by utility stakeholders to better understand state-wide risks, prioritize mitigation, plan new gas infrastructure, and help focus post-earthquake repair work.
The project team includes researchers from LBNL, UC Berkeley, UC San Diego, University of Nevada Reno, the NHERI SimCenter at UC Berkeley, and Slate Geotechnical Consultants and its subcontractors Lettis Consultants International (LCI) and Thomas O’Rourke. Focused research to advance the seismic risk assessment tool was conducted by Task Groups, each addressing a particular area of study and expertise, and collaborating with the other Task Groups.
This report is part of the product of Task Group C: Performance of natural gas storage well casing and caprock. The focus of this subtask report is the potential leakage through a caprock via activated faults. Advanced full-physics modeling was developed. Then Monte Carlo simulations were performed for failure analyses, with the goal of providing usable input to develop fragility (probability of failure) curves. The risk analysis followed the Performance-Based Earthquake Engineering (PBEE) framework provided by Moehle and Deierlein (2004). In this framework, the selected damage measure was cumulative gas leakage in the 30 years following fault rupture through the caprock. Simulations were run by varying parameter ranges. These ranges were selected to provide credible high side estimates of the damage measure. The simulations found both overpressure in the storage reservoir and substantial increase in fault damage zone permeability are needed for leakage to occur.
The method and steps demonstrated in this report could subsequently be followed by consideration of additional scenarios or more site-specific information to improve the fragility functions developed for the OpenSRA software.