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Reservoir Induced Seismicity-2

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  1. 1. Department of Earth Sciences KFUPM Introduction to Seismology Reservoir Induced Seismicity ( Reading Assignment: pp.384-386 ) Introduction to Seismology-KFUPM Ali Oncel [email_address]
  2. 2. Previous Lecture <ul><li>Reservoir Induced Seismicity </li></ul><ul><li>Earthquake Types </li></ul><ul><li>Volcanic Earthquakes </li></ul><ul><li>Humans Induced Seismicity </li></ul><ul><ul><li>Dam filling </li></ul></ul><ul><ul><ul><li>Example: Koyna Dam, India (M6.3, 1967) </li></ul></ul></ul><ul><ul><ul><li>Triggered earthquakes at Koyna (1967-200) </li></ul></ul></ul><ul><ul><li>Waste water injection </li></ul></ul><ul><ul><li>Oil extraction and Seismicity </li></ul></ul><ul><ul><ul><li>Example: The Romashkino Oil Field of Russia </li></ul></ul></ul><ul><ul><ul><li>Example: Interrelationship between Seismicity and Gas Injection in Talco area. </li></ul></ul></ul><ul><ul><li>Hot water extraction </li></ul></ul><ul><ul><li>Mining </li></ul></ul><ul><ul><li>Nuclear tests </li></ul></ul>Introduction to Seismology-KFUPM
  3. 3. Introduction to Seismology-KFUPM
  4. 4. • Dam Completed 1965 • M 6.2 seven months later , after rapid filling to 80m Kremasta Dam, Greece Introduction to Seismology-KFUPM
  5. 5. Monticello Dam, South Carolina <ul><li>Reservoir for cooling of nuclear power plant </li></ul><ul><li>• Seismometers in place since 1973 </li></ul><ul><li>Reservoir filled December 1977-Feb. 1978 </li></ul><ul><li>• Earthquakes start 3 weeks after filling starts </li></ul>Introduction to Seismology-KFUPM
  6. 6. Monticello seismicity concentrated under reservoir Introduction to Seismology-KFUPM
  7. 7. Monticello: Filling vs. seismicity Introduction to Seismology-KFUPM
  8. 8. Filling curves & Seismicity Rate Introduction to Seismology-KFUPM
  9. 9. Filling curves & large earthquakes Introduction to Seismology-KFUPM
  10. 10. • Earthquakes are associated with change in water level: with large scale filling of the dam, possibly with emptying • Seismicity often tapers off within ten years of water level stabilization • Variable time delays may occur between dam filling and earthquakes General characteristics of reservoir triggered seismicity Introduction to Seismology-KFUPM
  11. 11. Cause of reservoir triggered seismicity? <ul><li>• Stress increase from weight of the water? </li></ul><ul><li>Stress at surface usually equal to 1-3 bars </li></ul><ul><li>Stress at earthquake depths much less than that </li></ul><ul><li>Earthquake stress drop is about 30 bars </li></ul><ul><li>• Pore pressure increase reduces confining stress on faults? </li></ul>Frictional stress = coefficient of friction x pressure of rock (pressure of water) Introduction to Seismology-KFUPM
  12. 12. • Gas extraction greatly decreases pore pressure • Subsidence/earthquakes occur • Many small earthquakes in the Lacq Gas Field, France • Gazli gas field, Uzbekistan. Gas withdrawal started 1966; max production 1968-71. 2. M 7earthquakes in 1976, one in 1984. Were they induced?? • Some people have wondered about 1983 M 6.5 Coalinga earthquake, M 5.8 Does oil and gas extraction cause earthquakes? Introduction to Seismology-KFUPM
  13. 13. http://www.orfeus-eu.org/newsletter/vol3no2/ekofisk.html Mw=4.1-4.4 The May 7, 2001 Earthquake in the Ekofisk Oil Field Area, North Sea Introduction to Seismology-KFUPM
  14. 14. The seismic event was induced owing to stress changes caused by water injection (Ottemo¨ ller, et al., 2005, JGR, Vol.110). . Conclusion for 2001 EQ(M=4.4) Introduction to Seismology-KFUPM
  15. 15. Induced Event: M max : 4.3-1984 Introduction to Seismology-KFUPM
  16. 16. British Columbia Introduction to Seismology-KFUPM
  17. 17. M max =4.3 Introduction to Seismology-KFUPM Injection rate Seismicity
  18. 18. Location of the Valhall and Ekofisk oil fields are shown in a map of the southern Norwegian North Sea (a). A profile along line AA' illustrates the dome structure of the Valhall oil field (b). Introduction to Seismology-KFUPM A B
  19. 19. Microseismicity of Valhall Oil Area Introduction to Seismology-KFUPM
  20. 20. Introduction to Seismology-KFUPM
  21. 21. Seismicity Induced by Petroleum and Geothermal Activities Introduction to Seismology-KFUPM
  22. 22. Carthage Gas Field, East Texas Introduction to Seismology-KFUPM
  23. 23. Two event sub-clusters each delineating the intersection of two planes. Looking along line of intersection (top) and face-on views (bottom). Linear trends can be seen along fracture faces (bottom). The event sequences indicate early fluid invasion along linear trends.
  24. 24. Event rate changes correlate with production rate changes. Seismic response lags production by 2–3 weeks. Introduction to Seismology-KFUPM
  25. 25. Fracture planes are delineated by production-induced events occuring over a 6-month monitor period. Composite fault plane solutions indicate thrust displacement along the mapped, low-angle fractures. Induced stress changes are very small (<0.1 MPa). Introduction to Seismology-KFUPM
  26. 26. Small magnitude events were detected above the reservoir by placing a downhole receiver array within the upper 800 feet of an abandoned well. Event occurrence terminates near the base of the serpentine unit. WELL-BORE DEFORMATION The Geysers, California Introduction to Seismology-KFUPM
  27. 27. Both the above reservoir and the deeper reservoir seismicity show correlations with reservoir injection activity in the study area. WELL-BORE DEFORMATION The Geysers, California Introduction to Seismology-KFUPM