Quantitative Risk Assessment Approaches for Induced Seismicity. NRC Committee on Earth Resources Induced Seismicity and Energy Tech Washington, DC

Transcription

1 Quantitative Risk Assessment Approaches for Induced Seismicity NRC Committee on Earth Resources Induced Seismicity and Energy Tech Washington, DC Grant S. Bromhal, US DOE, NETL Josh White, LLNL November 4, 2013

2 NRAP s Induced Seismicity Working Group Lawrence Berkeley National Laboratory C. Bachmann T. Daley B. Foxall L. Hutchings T. Kneafsey J. Rutqvist H. Murakami-Wainwright National Energy Technology Laboratory G, Bromhal D. Crandall E. Lindner H. Siriwardane (WVU) Lawrence Livermore National Laboratory S. Carroll L. Chiaramonte S. Johnson W. Trainor-Guitton J. Wagoner J. White Pacific Northwest National Laboratory Z. Hou C. Murray Los Alamos National Laboratory C. Bradley B. Carey D. Coblentz R. Lee WG Lead: Joshua White, jawhite@llnl.gov External Collaborators J. Savy, Savy Risk Consulting J. Dieterich, UC Riverside

3 Some points from the NAS Study on Induced Seismicity CCS may have potential for inducing seismic events, but much is unknown. Methodologies can be developed for quantitative, probabilistic hazard assessments of induced seismicity risk. Need for federal agencies to coordinate on induced seismicity response.

4 National Risk Assessment Partnership Technical Team Wade, LLC Stakeholder Group

5 Typical scenario of concern Injection creates relatively small CO 2 plume, surrounded by larger plume of pressurized brine. Pressure increase along a welloriented fault could trigger seismic (or aseismic) slip. The fault is sufficiently large to produce concerning earthquakes. Fault is sufficiently small that it may have been unobserved or poorly characterized during site selection. Overall risk is controlled by several components in a complex system.

6 Typical scenario of concern * Figure not to scale Overall risk is controlled by several components in a complex system.

7 Four key risks associated with induced seismicity 1 Damage Risk Induced ground motions can damage nearby infrastructure 2 Nuisance Risk Induced ground motions can annoy nearby populations 3 Brine Leakage Risk Slip-enhanced leakage pathways can allow brine to contaminate protected groundwater. 4 CO 2 Leakage Risk Slip-enhanced leakage pathways can allow CO 2 to contaminate protected groundwater. Helpful to consider each separately. Though related, they have different physics, timescales, likelihoods, impacts, potential mitigation, etc.

8 High costs and large uncertainties suggest a phased approach to seismicity management Phase Characterization & Monitoring Site-screening Regional stress estimates Fault density estimates Pre-injection 3D seismic XLOTs FMI Limited microseismic Injection & PISC 4D seismic Full microseismic Modelling Back-of-theenvelope Risk Assessment Red-flags Atlas Simple models Qualitative Assessments PSHA Sophisticated models Traffic-light PSRA -- Cost/benefit of additional methods assessed based on evolving project conditions. -- Baselines are important. -- Timely processing and interpretation of data are important.

9 Probabilistic Seismic Risk Assessment PSRA is commonly used for dealing with natural seismic hazards. Framework is well-suited to dealing with induced seismicity, but must be modified to address differences between natural and induced events. Three key ingredients to a PSRA: Earthquake frequency/magnitude relationship. very challenging Ground motion hazard. mostly standard (some issues) Fragility curves. mostly standard (some issues) For CCS, framework also needs to be extended to capture leakage risks.

10 Approach to quantifying system performance is to use integrated assessment models (IAMs) to couple behavior of each component. A. Divide system into discrete components Potential Leakage Impacts (Atmosphere; Groundwater) Potential Ground-Motion Impacts (Ground Acceleration) fluid propagation Release/Transport of Fluids fluid propagation Reservoir (plume/pressure evolution) Slip along a Fault Plane seismic-wave propagation stress/pressure propagation Reservoir (plume/pressure evolution)

11 NRAP Integrated Assessment (System) Models NRAP approach to quantifying system performance A. Divide system into discrete components Energy Data Exchange (EDX) IAM B. Develop detailed component models that are validated against lab/field data Data from RCSPs etc. calibrate Potential Receptors or Impacted Media C. Develop reduced-order models (ROMs) that rapidly reproduce component model predictions E. Develop strategic monitoring protocols that allow verification of predicted system performance New Data from NRAP calibrate Release and Transport Storage Reservoir D. Link ROMs via integrated assessment models (IAMs) to predict system performance & risk; calibrate using lab/field data from NRAP and other sources

12 SIMRISK Framework SIMRISK is a framework for PSRA, specifically adapted to induced seismicity. Allows for flexible input, so that component modules may be easily swapped. Currently testing an earthquake simulation module based on RSQSim (Dieterich 1995; Richard- Dinger & Dieterich 2012) Validating against waste-water injection analogs.

13 Example earthquake frequency calculations Modeled data for a synthetic site in a seismically-active region [Foxall et al. 2012]. Background: y Injection: y Post-injection: y Zoom of injection period

14 Example ground motion intensity calculations For reference Background (0-200 y) Injecting ( y) 2 cm/s/s is barely perceptible by most people. 20 cm/s/s will cause light shaking but no damage. 200 cm/s/s can cause moderate to severe building damage.

15 Example fragility curves Fragility curves quantity likelihood of damage to a structure given a certain level of shaking. Same idea can be applied to a nearby population via nuisance curves [Majer et al. 2012]

16 NRAP is pursuing integrated, system-level models of Basin-scale ground motion and earthquake-caused fault leakage risk damage, nuisance, and leakage risk. assessment Ground'mo) on' Fault'leakage' D in#situ D Key science gap: permeability behavior of slipping faults.

17 NRAP induced seismicity development Generation 1 (July 2012) IAM for Probabilistic Seismic Hazards Assessment for single fault Generation 2 IAM for PSHA (June 2013) Multiple faults Multiple time periods Calculation of nuisance risk Parameter sensitivity calculations Report on Risk Assessment and Mitigation Strategies (January 2014) Generation 3 IAM for PHSA and risk (June 2014) Higher frequencies in ground motion 4000 Full risk Ties to fault leakage risk Induced Seismicity Protocol Document for CCS (Spring 2015) Northing (km) Pond-Poso Fault Greeley Fault New Hope Fault Easting (km)

18 Tentative Recommendations Site selection and characterization There are advantages to choosing sites in proximity to previous carbon storage or oil and gas developments. Obtain quality in situ stress estimates. Attempt to estimate fault density statistics and the largest unobserved fault. Under-pressured reservoirs may pose lower risk. Redundant seals are crucial, including shallow seals. Avoid downward pressure migration. The ground motion hazard attenuates quickly with distance. Operation and monitoring Deploy microseismic. Collect and analyze data in a timely fashion. Consider a slow ramp up to target injection rates. Falloff testing.

19 Conclusions 1. There will always be irreducible uncertainties associated with the seismic behavior of a field. That said, it is possible to choose sites that are robust with respect to seismic behavior. 2. There are four key risks associated with induced seismicity for CCS, and each has nuances that should be considered separately. 3. Seismicity deserves real attention when developing the characterization, monitoring, mitigation plans. A phased approach, combined with good contingency plans, can reduce cost while still addressing risk. 4. Probabilistic seismic risk assessment provides a rigorous, quantitative framework. Significant progress has been made adapting it to induced seismicity, but some important science gaps still exist.

20 Thank You! Questions?

21

22

23 Kimberlina Seismicity and Leakage Risk Hazard Assessment Northing (km) Pond-Poso Fault Greeley Fault New Hope Fault Easting (km)