Cooperative Research on Induced Seismicity In EGS Geothermal Resources Council Annual Meeting Sept 10-13 San Diego, C

1. Cooperative Research on Induced Seismicity In EGSGeothermal Resources Council Annual MeetingSept 10-13San Diego, California  Ernest Majer (1), Roy Baria (2) , Allan Jelacic (3) 1 Lawrence Berkeley National laboratory, 2 Miltech Inc, 3 USDOE

2. Presentation Outline Background and Objectives Process and Approach White Paper Overview Basis for a Protocol Results and Summary

3. Acknowledgements Funded by USDOE Geothermal Technology Program and many thanks the many people who contributed to the workshops, white paper (M. Stark, B. Smith, S. Oates, J. Bommer, and H. Asanuma) and the many reviews.

4. History There are numerous examples of induced seismicity associated with fluid injection (waste disposal, reservoir impoundment, dams, mining, oil production, geothermal.) (250,000 hits on Google , 100,000 are geothermal) Both natural and artificial ( induced permeability) geothermal systems demonstrate induced seismicity Seismicity concerns have stopped or delayed projects As EGS activity increases, seismicity may become an issue with the community as well as for the field operator. US DOE is participating in an international agreement with the IEA to address environmental issues associated with EGS.

5. GIA Annex I Subtask D “Participants will pursue a collaborative effort to address an issue of significant concern to the acceptance of geothermal energy in general but EGS in particular.”… “The objective is to investigate these events to obtain a better understanding of why they occur so that they can either be avoided or mitigated”.

6. Background and Objective Address Issues raised by IEA Agreement Form international working group to leverage resources Obtain current state of practice of addressing impact of induced seismicity on operational and cultural issues. Identify current gaps in knowledge and supply recommendations for future work on utilizing seismicity as a reservoir management tool Develop protocol for dealing with EGS induced seismicity to aid operators such that seismicity does not become an issue.

7. Process and Approach Draft LBNL internal Whitepaper (2004) Three international workshops (2005-2006) Form technical basis for understanding induced seismicity and a strategy for developing a protocol for designing “induced seismicity friendly” EGS projects Gather international group of experts to identify critical issues (technical and non technical) associated with EGS induced seismicity Form critical mass to leverage efforts and information to address key questions in a timely fashion Products (2006) Peer reviewed white paper ( IEA Report) Protocol for the development of geothermal sites and a good practice guide (IEA Report)

8. White Paper Summary and Overview  Introduction Objective Provide technical basis to develop a protocol Identify potential benefits of seismicity data Motivation EGS must play an important role in future energy supply Seismicity has become an issue but can be dealt with A cooperative , leveraged effort is required Relevant Seismic Concepts Faults and fractures are everywhere Induced seismicity is not unique to geothermal For “large” events to occur there must be sufficient faulting, stress build up and energy( depth) Damage is a function of ground motion and proximity

9. White Paper Summary and Overview  Induced Seismicity in Non- Geothermal Areas Dams/water impoundment 6.4 India Oil and Gas generally < 3.0, isolated mag 7 Subsidence Mining- Rock Bursts - local hazard Subsidence – surface facilities if large volume removal Waste disposal – mag 5.5 ( Rocky Mt. Arsensal) Almost all cases mitigated and dealt with effectively

10. White Paper Summary and Overview  EGS Systems - Natural and Induced Fractures Mechanisms of Induced Seismicity Pore Pressure Increase Temperature changes Volume Change Chemical alteration affecting slip surfaces Issues addressed/commonalities Technical – Pressure, volume , rates, chemistry etc. Public Concerns Case Histories ( 2 natural, 2 Induced) The Geysers - established, well studied, public concerns Cooper Basin - new, seismicity, remote, high EGS potential El Salvador – Representative, mitigation system emplaced Soultz – Directly affected by seismicity, large data base

11. The Geysers Historical seismicity (M 3.0 to 5.0) 1900- 2004

12. The Geysers Seismicity, 1965 to Present (Smith,2005)

13. Cooper Basin Seismicity

14. Berlin, El Salvador Traffic Light Example

15. Recommended levels of vibration versus ground motion (USACE)

16. Soultz, France

17. Soultz seismicity versus injection

18. White Paper Summary and Overview  Gaps in knowledge Relationship between the small and large events Similar mechanisms and patterns Threshold of events/ triggered? Why do large events occur after shut in. Source parameters of events Stress drop versus fault size Indication of stress heterogeneity? Seismicity on existing versus new faults/fractures Experiments to shed light on mechanisms Variation of key parameters ( injection rate, vol., temp, pressure,etc.) Differences between Natural and Induced fracture systems Maximum size , time of events Can one manipulate seismicity without compromising production? Does the reservoir reach equilibrium?

19. A Basis for a Protocol Technical Identify and understand factors controlling microseismicity Effect of microseismicity on man made structures Community Interaction Propose guidelines for a geothermal developer to deal with the issue of induced seismicity. Inform and interact with the community to understand their concerns and partner with them to achieve a win-win situation Both are linked and overlapping

20. Protocol : Technical issues

21. Protocol : Technical issues (cont’d) Assess Induced Seismicity Potential (Cont’d) A plan for responding to induced seismicity (Bommer et al 2006 or others) Establish microseismic monitoring network A high resolution microseismic monitoring network is essential to evaluate what changes may be going on in the reservoir, in conjunction with other diagnostic techniques. The high resolution network should be linked with a regional network if possible. The network should be installed prior the commencement of any fluid injection in to the formation.

22. Protocol : Technical issues (cont’d) Improve understanding of the generation of large induced events so that procedures are incorporated to reduce them. Sharing of seismic data and experience in various geological setting Encouraging further research on topics such as a) the trigger mechanism for larger events b) characterisation of bigger events, c) the influence of stress migration d)large injection volume for stimulation e) the influence between injected volume and production volume f) Effect of thermal stress etc. One of the mechanism for such research and cooperation is through IEA/GIA platform.

23. Community Interaction Local & National Regulation/laws on induced seismicity. Review national + local regulations and laws on induced seismicity Any legal precedents which includes induced seismicity should be identified and assessed relative to the proposed project. Formulate a plan for meeting any legal requirement. Recognise the fact that induced seismicity and it’s effect on public and man made structure are exceedingly rare (Cypser & Davis 1998) . In absence of any regulatory guidance on induced seismicity, assess and adapt mining or civil engineering regulations (?)

24. Community Interaction (cont’d) Establish a dialog with Regional Authority & Educate Public Communicate with Regional Authority ASAP: purpose of the project, site under consideration, effect on the environment and residents, benefit to the local economy etc. Obtain support from the local authority on communication and permits required for the installation of the infrastructure. Make public announcement of the EGS project and its benefits. Regular public meeting on the progress of the project, explain the method used for reservoir development & the temporary effect such as increased noise, microseismicity, increased traffic etc. Web sites Point of contact

25. Community Interaction (cont’d) Implement procedure for Evaluating Structural damage A developer in conjunction with the local authority should establish criteria for structural damage. May require permanent installation of few strategically placed surface mounted strong motion seismometers to measure peak velocity & dominant frequency. Regular reporting of background noise, seismic measurement among other environmental effects to provide quantitative basis for judgement to be fair to both sides, public and operator.

26. Overall Results and Conclusions Technical basis for understanding and controlling EGS induced seismicity has been established. White paper and draft protocol finished Issues are similar to other induced seismicity cases which have been successfully addressed Issues are both technical and non-technical Must pay attention to both Seismicity can be a benefit in understanding the resource Technical issues remain on fully utilizing seismicity as a reservoir management tool Induced seismicity is not (or need be ) an impediment to EGS development