3rdworkshop

Updates: 

Updates White Paper outline Home Page http://esd.lbl.gov/EGS/ Potential Data Sets Phillipines, Glenn Golla Tiwi, Nordquist Turkey, Ali Kahn Salton Sea, Ben Barker Europe, Baria Mexico , Allan Jelacic New Zeland, Chris Bromley Australia Doone Wyborn Geysers Majer, Stark, Smith Meetings Sept 3-8 Geneva Switz 1st European Conf On EE& Seis http://www.ecees.org/

First EGS Workshop Results: 

First EGS Workshop Results 38 participants attended a two day DOE/IEA meeting held at Stanford/USGS in Feb 05 to develop a path forward on assessing and mitigating seismic risk Purpose Gather international group of experts to identify critical issues associated with EGS induced seismicity Form critical mass to leverage efforts and information to address key questions in a timely fashion y Provide set of recommendations for moving forward on mitigating/controlling induced seismicity

Technical Issues Identified: 

Technical Issues Identified Is it possible to mitigate and optimise production at the same time? Does the reservoir reach an equilibrium? What are the critical parameters necessary to estimate the seismicity hazard? What measurements and data are lacking, and if additional data are needed, how much and how long should monitoring continue? What can we learn from other induced seismicity cases? general seismicity? Can Probabilistic Seismic Hazard Analysis (PSHA) be used for Geothermal areas to estimate the largest events? How does one explain the occurrence of large events when there are no large faults? Are there experiments that can be performed which will shed light on key mechanisms causing EGS seismicity?  How does induced seismicity mitigation differ in naturally fractured systems versus hydrofracturing environments?

2nd Workshop : 

2nd Workshop White Paper Outline   I.   Introduction a.      Purpose and Objective       i.      Group, what lead to activity, etc b.      Why EGS c.      History of Induced Seismicity II.       Description of EGS Systems a.      Background seismicity b.      Engineered – description of seismicity c.      Natural – description of seismicity d.      Role of fluids, recharge, stress, strain

Slide5: 

III.  Case Histories a.      Technical b.      Public c.      Commonalities d.      Lessons learned IV.     Mechanisms a.      Discussion of possible explanations           i.      When and why are there induced events b.      Lead to bigger “natural” events V.      Mitigation Measures

Slide6: 

VI.    Public Interaction a.      Public education: industry-public partnership, communication issues (e.g scientific jargon), knowledge, dissemination, satisfaction b.      Hazard assessment – ML vs. Ground motion              i.      Mining and waste injection experience              ii.      Cumulative effects of minor events              iii.      Community benefits (e.g. clean power on the grid) c.      Regulations – federal, state VII.      Gap in Knowledge a.      Production tools – b-value, rate, etc. VIII.         Conclusions, Future Needs, Commonalities, Current Activities, Future actions

Potential Case HistoriesDOE/CEC projects Geysers:Desert peak:: 

Potential Case Histories DOE/CEC projects Geysers: Desert peak:

Hypothesis for Induced Seismicity: 

Hypothesis for Induced Seismicity Increased pore pressure (effective stress changes) Thermal stress Volume change (subsidence, inflation) Chemical alteration of slip surfaces Stress diffusion Production induced Injection produced Etc.

Geysers Objectives: 

Geysers Objectives Provide information to evaluate and manage the effect of induced seismicity on EGS activities Will induced seismicity concerns prevent EGS from reaching its goal? What are critical parameters to understand and monitor to optimize production as well as control seismicity. Implications for injection and production strategy Impact on local community Impact on operations Interface with other EGS projects to accelerate knowledge and results

Plans and Approach: 

Plans and Approach Initial focus is on The Geysers. Large background data base NW Geysers a large potential source of EGS production (Aidlin/Ottobani Ridge area) Utilize and expand existing LBNL array for providing data to the community and other researchers Leverage DOE project with CEC project Investigate underlying cause and utility of seismicity as well as ability to mitigate seismicity Integrate and apply results to other EGS projects. International as well as domestic. Large challenge, only way to advance is to pool resources, data, and results.

CEC Project: 

CEC Project Four coordinated tasks are proposed: An enhanced analysis of MEQ data Permanent scatter InSAR data of surface deformation A coupled thermal-hydrologic-mechanical analysis of fluid injection and withdrawal Develop a conceptual and quantitative understanding of physical and chemical processes induced by water injection

Timeline: 

Timeline Stabilize and expand Geysers array to Aidlin (2004) Investigate “virgin area” response to injection Provide complete data set to public and scientific community(2004- 2006) Integrate and leverage work with international community (2005-2006) Organize and participate in workshops Interchange data and results (2005 and 2006) Integrate with geochemical and reservoir engineering studies (2005-2006) Expand studies to other U.S. sites (2005-2006) Publish and disseminate results ( ongoing)

Slide13: 

19 26 26 0 200 400 600 800 1,000 1,200 1965 1970 1975 1980 1985 1990 1995 2000 Earthquake Count 0 20 40 60 80 100 120 Steam Production and Water Injection (mgd) Earthquake Count M>=1.5 Earthquake Count M>=3.0 Earthquake M>=4.0 Steam Production Water Injection Historical seismicity from 1965 to the present at The Geysers. Data are from the NCEDC. The largest event recorded was a Mag 4.6 in 1984. The Green dashed line shows the seismicity mag 1.5 and above, the solid green line shows the seismicity above 3.0. Historical Geysers Seismicity

Slide14: 

Location of USGS stations, Current Calpine array, and the new LBNL stations. Also shown are the locations of the pipelines used for the water from Santa Rosa. (from Calpine) Aidlin

Slide15: 

Aidlin Injection Well Current Array

Slide16: 

Total Injection prior to Jan 1, 2003

Slide17: 

Total Injection after Jan 1, 2003

Slide19: 

( > 30K ) Dec 2005 Aidlin Nov 2005

Slide20: 

Number of Events

Slide21: 

Energy Released

Slide22: 

Number of Events

Slide23: 

Energy

Slide24: 

y = -1.2656x + 4.8502 y = -1.089x + 3.888

Geysers Summary: 

Geysers Summary Weak correlation with injection Large events ( >4.0) have less correlation with injection Total seismicity increasing with injection Total energy rate slightly increasing with injection In new areas immediate increase with injection (all events however are less than 1.5M)

Desert Peak EGS Site: 

Desert Peak EGS Site EGS Injection well 3-C Borehole Microseismic Array

Slide27: 

Project area, well and fault locations EGS area