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Cooperative Research on Induced Seismicity In EGS

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					Cooperative Research on Induced Seismicity
                 In EGS

       Geothermal Resources Council
             Annual Meeting

                     Sept 10-13
                San Diego, California

 Ernest Majer (1), Roy Baria (2) , Allan Jelacic (3)
      1 Lawrence Berkeley National laboratory, 2 Miltech Inc, 3 USDOE
        Presentation Outline
• Background and Objectives
  – Process and Approach
• White Paper Overview
• Basis for a Protocol
• Results and Summary
         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.
                       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.
       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”.
      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.
                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)
       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
      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
         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
The Geysers Historical seismicity (M 3.0 to 5.0) 1900- 2004




        The Geysers
The Geysers Seismicity, 1965 to Present                                                                                       (Smith,2005)
                                                         Geysers Annual Steam Production, Water Injection and Seismicity



                                   1,400                                                                                             350




                                                  Seismic Events of M>=1.5                                                     1158
                                   1,200                                                                                             300
                                                  Earthquake Count M>=3.0
                                                  Earthquake M>=4.0




                                                                                                                                           Steam Production and Wa ter Injection (billion lbs)
                                   1,000          Steam Production                                                                   250
Annual Number of Seismic Eve nts




                                                  Water Injection

                                    800                                                                                              200




                                    600                                                                                              150




                                    400                                                                                              100




                                    200                                                                                              50


                                                                                                                                12
                                                                                        26                26
                                      0                                                                                              0
                                           1965   1970         1975       1980       1985        1990       1995       2000   2005
Cooper Basin Seismicity
             400


             200


               0




     NS(m)
             -200

             -400


             -600

                    -200   0   200   400   600   800
                                EW(m)



             400


             200


               0
     NS(m)




             -200


             -400


             -600

                    -200   0   200   400   600   800
                                EW(m)
Berlin, El Salvador Traffic Light Example
Recommended levels of vibration versus ground motion (USACE)
Soultz, France
Soultz seismicity versus injection




                  ~2.9 M (10June03;22:54)
        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?
           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
           Protocol : Technical issues
•   Assess Natural Seismic Hazard Potential of a proposed site.
–   Look up historical seismic data
– Look at the geological and stress conditions
–   Assess the occurrence of it in the future (b-value)
•   Assess Induced Seismicity Potential
– From geological and stress data evaluate likely generation of large
  seismic event due to the activity of an EGS project.
–   Establish quantification for the size of events using peak velocity
    and dominant frequency (as in mining and civil eng) & not Ml.
–   Evaluate (& possibly avoid) areas where buildings are constructed
    on unconsolidated deposits from mining or other activities.
    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.
 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.
        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 (?)
     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
    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.
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